taxonID	type	description	language	source
03F2DF380248FFB3FDFC4FEEFC4D7EAC.taxon	description	urn: lsid: zoobank. org: act: 3 A 061 F 94 - 72 BB- 4 EBA-BB 1 B-F 022 A 4 F 96 D 4 C Figs 1 – 3	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380248FFB3FDFC4FEEFC4D7EAC.taxon	diagnosis	Diagnosis Callioplana marianae sp. nov. is characterized by a beige background coloration with light brown and white pigmentation that gives it a reticulated appearance, nipple-shaped nuchal tentacles, cerebral and tentacular eyes, absence of marginal eyes, a folded pharynx located slightly posterior to the first third of the body, separated gonopores, an oval seminal vesicle located posterior to the free prostatic vesicle that presents a striated internal glandular lining, a penis papilla armed with a filiform stylet, and a tripartite Lang’s vesicle located posterior to the male gonopore.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380248FFB3FDFC4FEEFC4D7EAC.taxon	etymology	Etymology This species is named after the author’s beloved mother Mariana Sánchez.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380248FFB3FDFC4FEEFC4D7EAC.taxon	materials_examined	Type material Holotype MEXICO • 1 ⚥ (as sagittal sections); southern Mexican Pacific, Oaxaca, Zipolite, Camarón Beach; 15 ° 39 ′ 43 ″ N, 96 ° 31 ′ 33.6 ″ W; depth 0.5 m; 25 Mar. 2017; MRS, MB, AMRM, NMP leg.; in rocky intertidal; reproductive structures in two slides; UMAR PLAT – 046. Paratypes MEXICO • 8 ⚥⚥, 6 (as whole assemblies), 1 (as front section); same data as for holotype; UMAR PLAT – 047 A – D, UMAR PLAT – 048. Type locality Camarón Beach, Zipolite, Oaxaca, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380248FFB3FDFC4FEEFC4D7EAC.taxon	description	Description of external features Holotype (⚥ UMAR PLAT – 046) COLOR. The background color is beige with brown to olive green; the periphery is slightly translucent with light brown and white pigmentation; the reticulate coloration pattern radiates from the central region of the pharynx to the periphery of the body (Fig. 1 A), the ventral region is white. Specimens stained with Mayer’s carmalum are pink (Fig. 1 C – D). BODY. Elliptical (Figs 1 A – D, 3 A), 15 – 20 mm long (n = 5, μ = 18, SD = 2) and 10 – 12 mm wide (n = 5, μ = 11, SD = 1). TENTACLES. Rudimentary nipple-shaped nuchal tentacles (Figs 1 F, 3 B) are located in the anterior margin of the body, the distance between tentacles being 0.6 – 0.9 mm (n = 3, μ = 0.7, SD = 0.16). EYES. Marginal eyes absent; with 17 – 25 (n = 3, μ = 20, SD = 3) tentacular eyes, diagonally distributed, anterior and posterior to the base of the nuchal tentacles (Figs 1 F, H, 3 A – B); with 17 – 36 (n = 3, μ = 22, SD = 7) cerebral eyes distributed in an elongate fashion beginning sparsely at the posterior margin of the brain and widening forward (Figs 1 H, 3 B). BRAIN. Bilobed, 0.2 – 0.6 mm (n = 3, μ = 0.4, SD = 0.28) long and 0.2 – 0.7 mm (n = 3, μ = 0.5, SD = 0.31) wide; globuli cell masses oval-shaped, located in the anterior region of the brain (Figs 1 E, 3 B). DIGESTIVE SYSTEM. The pharynx is relatively small and sparsely folded; located slightly posterior to the first third of the body at 5 mm (n = 3, μ = 0.5, SD = 0.31) from the anterior margin of the body (Figs 1 G, 3 A), 1 – 1.3 mm (n = 3, μ = 1.2, SD = 0.19) from the male gonopore; the mouth is located in the central region of the pharynx. GONOPORES. Separated, located in the last third of the body (Fig. 3 D). Male gonopore at 6 – 6.3 mm (n = 3, μ = 6.2, SD = 0.21) from the anterior margin and 1 – 1.3 mm (n = 3, μ = 1.2, SD = 0.19) from the pharynx. The female gonopore (Fig. 2 F – G) is positioned posterior to the male gonopore at 0.5 – 0.8 mm (n = 3, μ = 0.6, SD = 0.02) of distance. Description of internal features MALE REPRODUCTIVE SYSTEM. The male gonopore is located in the last third of the body; the rest of the male reproductive system is oriented toward the anterior part of the male gonopore; it has spermiducal ducts that are oriented toward the anterior region of the body and extend to the last third of the pharynx and subsequently descend toward the posterior region of the body. A prominent oval-free prostatic vesicle (Figs 1 I, 2 D, 3 C – D), with internal ridged glandular lining (Figs 2 D, 3 C), is located dorsal to the seminal vesicle (Figs 2 A, D, 3 C). Oval seminal vesicle (Figs 2 D, 3 C – D). Penis papilla is short (Figs 1 I, 2 F), 94 µm long, armed with a long filiform sclerosed stylet (Figs 2 B, E, G, 3 C – D), measuring 200 – 400 µm (n = 3, μ = 300, SD = 141.42) in length. The male atrium is widened (Figs 2 G, 3 C). FEMALE REPRODUCTIVE SYSTEM. The oviduct, oriented toward the anterior region of the body, surrounds the pharynx (Fig. 3 A) and connects directly to the proximal end region of the vagina; the vagina is sparsely developed (Figs 2 C, 3 D), oriented toward the posterior region of the body, cement glands are abundant. Lang’s vesicle tripartite is Y-shaped (Figs 1 I, 2 A, 3 C); the proximal ends are oriented towards the anterior region of the body and reach the last third of the oviduct, while the distal end is oriented towards the posterior region of the female gonopore. Taxonomic remarks Within the TEP, Callioplana marianae sp. nov., Hylocelis californica (Heath & McGregor, 1912), and Interplana sandiegensis (Boone, 1929) share a tripartite Lang’s vesicle. However, Callioplana marianae has a free prostatic vesicle (Figs 2 D, 3 D), whereas H. californica and I. sandiegensis have an interpolated prostatic vesicle. Additionally, Callioplana marianae possesses nuchal tentacles (Figs 1 H, 3 B) and a penis papilla (Fig. 2 F), features that relate it more closely to the family Callioplanidae than to others within the suborder Acotylea. The family Callioplanidae has 14 valid genera, and the new species described here belongs to the genus Callioplana and is established as Callioplana marianae sp. nov., due to the presence of nuchal tentacles, cerebral and tentacular eyes and a highly developed Lang’s vesicle; this last character is absent in the genera Asolenia Hyman, 1959, Crasiplana Hyman, 1955, Discostylochus Bock, 1925, Kaburakia Bock, 1925, Meixneria Bock, 1913, Okakarus Holleman, 2007, Parastylochus Bock, 1913, Tokiphallus Faubel, 1983, and Trigonoporus Lang, 1884. Callioplana marianae sp. nov. is further distinguished from the genus Koinostylochus Faubel, 1983, which has a simple and oval Lang’s vesicle, in contrast to the tripartite and highly developed Lang’s vesicle of the new species. Additionally, Callioplana marianae lacks marginal eyes, a feature that separates it from the genera Ancoratheca Prudhoe, 1982, Munseoma Bulnes, Faubel & Park, 2005 and Neostylochus Yeri & Kaburaki, 1920, all of which have marginal eyes. The genus Callioplana was established by Stimpson (1857) and amended by Yeri & Kaburaki (1918). It is characterized by the presence of nuchal tentacles, cerebral and tentacular eyes, a rod-shaped penis papilla (or “ a rod-shaped muscular extension of the ejaculatory duct, with an outward bulge ” as was mentioned by Faubel 1983) and a highly developed Lang’s vesicle. Previously, two species were described in Callioplana: C. marginata Stimpson, 1857 from Japan, and C. evelinae Marcus, 1954 from San Sebastian Island, Brazil. Both species differ from C. marianae sp. nov. in the color and pattern of dorsal coloration, the position of the prostatic vesicle (Table 1), and essentially in the morphology of a Lang’s vesicle (tripartite and Y-shaped in C. marianae vs bifurcated in C. marginata and C. evelinae) and a penis papilla (armed with a filiform stylet in C. marianae, vs unarmed in C. marginata and C. evelinae).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380248FFB3FDFC4FEEFC4D7EAC.taxon	distribution	Distribution and habitat Tropical Eastern Pacific. Central coast of Oaxaca: Camarón Beach, Zipolite, Oaxaca, Mexico. Intertidal, the polyclads were found under rocks in the breakwater zone.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380242FFB2FE434C14FD1D7D44.taxon	distribution	Distribution The species is found from Puget Sound to the Revillagigedo Islands in the Mexican Pacific, including locations such as San Juan Island in Puget Sound, Depoe Bay in Oregon, and various sites along the California coast such as San Francisco Bay, Monterey Bay, and Anacapa Island. It is also recorded in Baja California, specifically Roca Consag in Baja California Sur, Mexico, and Clarion Island near Manzanillo, Colima, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380242FFB2FE434C14FD1D7D44.taxon	biology_ecology	Habitat Benthic. The species inhabits depths ranging from 18 m to 70 m (Heath & McGregor 1912; Freeman 1933; Hyman 1953 a).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380242FFB2FE434C14FD1D7D44.taxon	discussion	Remarks The species was initially described as Planocera burchami by Heath & McGregor (1912) in Monterey Bay, California, and later as Discosolenia washingtoniensis by Freeman (1933) in Puget Sound. Hyman (1953 a) reviewed specimens from these localities and from the Gulf of California, along with the original descriptions by Heath & McGregor (1912) and Freeman (1933), and concluded that they were the same species, thus establishing all specimens as Pseudostylochus burchami. Faubel (1983) subsequently transferred the species to the genus Koinostylochus based on the presence of a prostatic vesicle with a smooth glandular lining dorsal to the male atrium and an inert penis papilla. Freeman (1933) described Koinostylochus burchami as having a male reproductive apparatus with a short, sharp penis papilla armed with small spines; however Hyman (1953 a), after reviewing specimens from the same locality and the description of the species by Freeman (1933), stated that this character is absent and considered it an error, Hyman (1953 a) also noted that the presence of the two deep pits observed by Heath & McGregor (1912: pl. 18 fig. 44) is at the superficial level because in the sagittal sections of the reproductive system, they are not observed. Therefore, a thorough revision of the biological material of the species is suggested.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380243FFB1FE544D10FAAA79A7.taxon	distribution	Distribution Santa Cruz Island, Galapagos Archipelago, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380243FFB1FE544D10FAAA79A7.taxon	biology_ecology	Habitat Interstitial.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380243FFB1FE544D10FAAA79A7.taxon	discussion	Remarks The species was transferred to the genus Eucestoplana, proposed by Faubel (1983), and is characterized by scattered frontal eyes-spots. The male reproductive system features a true seminal vesicle and a tubular penis stylet, housed in an elongated male atrium and the female complex lacks Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380240FFB1FDA84FD4FC1B7EC8.taxon	distribution	Distribution Clipperton Island. Habitat Benthic (under rocks to the south of the landing place of the island).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380240FFB1FDA84FD4FC1B7EC8.taxon	discussion	Remarks Faubel (1983) transfers Euplana clippertoni to the genus Aprostatum, because the species has a male reproductive system with a penis papilla armed with a pointed tubular stylet and female reproductive system with Lang’s vesicle; characters absent in the genus Euplana.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380240FFB1FDD34933FACA7C08.taxon	distribution	Distribution Tagus Cove, Isabela Island, Galapagos Archipelago, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380240FFB1FDD34933FACA7C08.taxon	biology_ecology	Habitat Benthic (sandy bottom, at depths of 18 – 36 m).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380240FFB1FDD34933FACA7C08.taxon	discussion	Remarks Cryptocelis insularis is distinguished from all previously described valid species of Cryptocelis by its scarcity of eyes, the limitation of the marginal eyes to the anterior body region, and the division of the eosinophilous and cyanophilous part of the prostatic vesicle into narrow transverse chambers.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380240FFB0FE724C70FD687B30.taxon	distribution	Distribution Santa Cruz Island, Galapagos Archipelago, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380240FFB0FE724C70FD687B30.taxon	biology_ecology	Habitat Interstitial (coarse intertidal sediments) or rocks.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380240FFB0FE724C70FD687B30.taxon	discussion	Remarks Faubel (1983) considered E. horrida a very primitive species due to its of any penis papilla and seminal vesicle, its very simplified male tract, and a female system with Lang’s vesicle connected with the exterior by a Lang’s duct (ductus vaginalis). Between the two female apertures, an accessory female organ opens to the exterior independently.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380241FFB0FDD84878FD5A7F97.taxon	distribution	Distribution Valparaíso, Chile; Coast of Peru; Point San Marcial reef, Baja California Sur, Miramar Beach, Guaymas, Sonora, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380241FFB0FDD84878FD5A7F97.taxon	biology_ecology	Habitat Fouling (adhered to the keel of a vessel (Plehn 1896 )), benthic (Hyman 1953 a).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380241FFB0FDD84878FD5A7F97.taxon	discussion	Remarks Plehn (1896) initially described Euplanoida pacificola in Valparaíso, Chile, after collecting specimens on the keel of a ship. The species was subsequently recorded along the coast of Peru, initially considered to be a variety of E. pacificola. Hyman (1953 a) later reported it from the coast of the Gulf of California, identifying the species as a Mexican variant. However, Hyman (1953 a) overlooked possible morphological differences in the reproductive system and the geographic distribution. She argued that such variations and geographic distribution did not justify separation into distinct species. Based on a review of the descriptions and illustrations provided by Plehn (1896) and Hyman (1953 a), this study suggests a detailed review and comparison of the biological material assigned to Euplanoida pacificola, as differences were found in the distribution of the cerebral and tentacular eyes, the morphology of the pharynx, the penis papilla and Lang’s vesicle (review the work of Ramos-Sánchez et al. 2019). In addition, it is necessary to review the structure identified as Lang’s vesicle, since Plehn (1896) describes it as a bursa copulatrix.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380246FFB7FEDB4A18FC337B71.taxon	distribution	Distribution Camarón, Puerto Ángel, Estacahuite and Yerbabuena beaches, Oaxaca; southern Mexican Pacific.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380246FFB7FEDB4A18FC337B71.taxon	biology_ecology	Habitat Benthic, littoral to sublittoral (12 m); under rocks, associated with green seaweed, bryozoans and chitons.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380246FFB7FEDB4A18FC337B71.taxon	discussion	Remarks The separation between Euplanoida cf. pacificola and the nominal species is difficult, mainly due to the ambiguous information in the original description, the possible artifacts from the process of fixation and / or different life stages of the specimens, and the color variations between the specimens reviewed by Plehn (1896), Hyman (1953 a) (see remarks on Euplanoida pacificola).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380246FFB7FE4148BAFDAB7EC7.taxon	distribution	Distribution Playa de los Muertos, Puerto Vallarta, Jalisco, Puerto Ángel, Oaxaca, México; Manuel Antonio National Park, Guanacaste, Costa Rica; Naos Island at the Pacific entrance of the Panama Canal, Punto Chocolatera, Salinas, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380246FFB7FE4148BAFDAB7EC7.taxon	biology_ecology	Habitat Commensal (mantle cavities of Cerithium stercusmuscarum Valenciennes, 1832, Echinolittorina modesta (R. A. Philippi, 1846), E. apicina (Menke, 1851), E. conspersa (R. A. Philippi, 1847), E. tenuistriata (D. Reid, 2002), Lottia mesoleuca (Menke, 1851), Nerita scabricosta Lamarck, 1822, N. funiculata Menke, 1850, Planaxis planicostatus G. B. Sowerby I, 1825, Tegula pellisserpentis (W. Wood, 1828 )).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380246FFB7FE4148BAFDAB7EC7.taxon	discussion	Remarks Paraprostatum echinolittorinae is characterized by a male reproductive system with a long stylet enclosed by a strong muscular bulb; a long vagina partially provided with circular muscle fibers and epithelial cilia, communicating with a bilateral uterus; absence of Lang’s vesicle; cerebral eyes and presence of nuchal tentacular knobs.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380246FFB6FE554C70FBAF7AE2.taxon	distribution	Distribution Carbón Beach, Las Baulas National Marine Park of Guanacaste, Costa Rica.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380246FFB6FE554C70FBAF7AE2.taxon	biology_ecology	Habitat Benthic, low intertidal, below stones on sand.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380246FFB6FE554C70FBAF7AE2.taxon	discussion	Remarks The genus Semonia currently comprises two described species: S. maculata Plehn, 1896 and S. bauliensis, S. maculata has an ivory background color, with honey brown coloration in the pharynx and reproductive system areas. Nuchal tentacles, tentacular eyes, and cerebral eyes are present. The genital atrium is common, and the male reproductive system consists of a seminal vesicle and a short, rod-shaped penis papilla, lacking a prostatic vesicle. The female reproductive system consists of an elongated, S-shaped vagina, gradually widening distally, without Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380247FFB6FD8B484AFCA77F60.taxon	distribution	Distribution Santa Cruz Island, Galapagos Archipelago, Ecuador. Habitat Interstitial.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380247FFB6FD8B484AFCA77F60.taxon	discussion	Remarks Marcus & Marcus (1968) initially established the genus Amyris within the family Planocerida Poche, 1926, characterizing it by the presence of a seminal vesicle, interpolated prostatic vesicle and a cuticularized cirrus without spines, in addition to the presence of a Lang’s vesicle. Subsequently, Faubel (1983) transferred the genus to the family Notoplanidae based on the morphology of the prostatic vesicle. Özdikmen (2010) mentioned that the species is included in the family Notocirridae (family that includes the genera Amyris, Chiliplana, Copidoplana, Diplandros, Faubelus, Notoplehnia, Triadomma and Tripyloplana); however, he did not establish the criteria for its reassignment. Özdikmen (2010) proposed renaming the family Notocirridae due to its invalidity under the rule of homonymy, being a junior homonym of Notocirrus Schmarda, 1861 (a name proposed for polychaetes of the genus Notocirrus), and in accordance with article 60 of the International Code of Zoological Nomenclature, fourth edition (ICZN 1999), he proposed to replace the junior homonym Notocirrus Faubel, 1983 with the nomen novum Faubelus. However, Amyris favis should not be included in this family, because the diagnostic characters do not correspond to those established in the family and instead it should be considered as a member of Notoplanidae as established by Faubel (1983).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380244FFB5FDDA4A58FC287C31.taxon	distribution	Distribution San Clemente Island, La Jolla, California; La Ensenada, Baja California, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380244FFB5FDDA4A58FC287C31.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380244FFB5FDDA4A58FC287C31.taxon	discussion	Remarks Diplandros singularis has cerebro-tentacular eyes and a double male reproductive system located in the anterior part of the paired male gonopore. In addition, it has an interpolated prostatic vesicle and a Lang’s vesicle oriented towards the anterior region of the body. Hyman (1953 a) was the first to describe the species, placing it in the family Leptoplanidae Stimpson, 1857. However, she noted that the internal morphological arrangement of Diplandros is based on the internal plan of Notoplanides (review the comments of Amyris favis).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380244FFB5FE454F79FB1B7F36.taxon	distribution	Distribution Santa Cruz Island, Galapagos Archipelago, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380244FFB5FE454F79FB1B7F36.taxon	biology_ecology	Habitat Benthic (rock pool).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380244FFB5FE454F79FB1B7F36.taxon	discussion	Remarks Tripyloplana virgae are described by Sopott-Ehlers & Schmidt (1975) within the genus Copidoplana. Faubel (1983) transferred the species to the genus Tripyloplana (family Notoplanidae), based on the presence of a separate male and female atrium; a character that in the genus Copidoplana is determined as a common genital atrium. Review the remarks of Amyris favis on the change of family.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380245FFB4FDB94A7DFB567F3C.taxon	distribution	Distribution Cosmopolitan distribution. Bermuda; Gulf of Mexico; Caribbean Sea; La Paz Bay, Baja California Sur; off West African coast (21 ° – 35 ° N, 36 ° – 38 ° W) (Mertens 1832); off West African coast (9 ° 21 ′ N, 18 ° 25 ′ W and 5 ° 48 ′ N, 14 ° 20 ′ W) (Moseley 1877); West Africa and Madeira (Graff 1892); dredged in about 2 meters at Boa Vista, Cape Verde Island (Laidlaw 1906).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380245FFB4FDB94A7DFB567F3C.taxon	biology_ecology	Habitat Epibiont (commonly found on Sargassum C. Agardh, Halimeda J. V. Lamouroux, Rhizophora L., Thalassia Banks ex König and Ulva L.); coastal surface and epipelagic; pelagic (neustal, hyponeustal organism), associated with Halobates Eschscholts, 1822; or benthic (sandy bottom).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380245FFB4FDB94A7DFB567F3C.taxon	discussion	Remarks This polyclad is common on Sargassum and is found on floating weeds in various parts of the world. Marcus & Marcus (1968) recorded it as an epibiont species on seaweeds of the genera Halimeda, Rhizophora, Thalassia, and Ulva. They also associated it with habitats such as sandy bottom, sandy shore with reef debris, and sandy flat with Cymodocea K. D. König and Thalassia. Cheng & Lewin (1975), using zooplankton samples, identified a pelagic polyclad species in the Bay of La Paz, Baja California Sur, which they named G. sargassicola. However, their record is considered questionable in this study due to the lack of a detailed description of the specimens.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025AFFABFDC94A7DFB8A7BD1.taxon	distribution	Distribution Balboa Park, Panama.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025AFFABFDC94A7DFB8A7BD1.taxon	biology_ecology	Habitat Commensal (Nerita scabricosta).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025AFFABFDC94A7DFB8A7BD1.taxon	discussion	Remarks A distinctive feature of the genus Hoploplana is the absence of a seminal vesicle, with highly developed spermiducal bulbs and a short stylet attached directly to the prostatic vesicle (Laidlaw 1902). A thorough review the biological material of the species is recommended, as Smith (1961) gave a not very detailed description and in the illustrations of the male reproductive system, it is observed that the stylet is positioned dorsal to the prostatic vesicle, this prostatic vesicle is elongated, pointed and connected to the spermiducal bulbs through an ejaculatory duct (see Smith 1961: pl. 16 fig. 4).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025AFFAAFD864F78FAB579FB.taxon	distribution	Distribution Puerto Don Juan, Punta de Malo, Bahía de los Ángeles, Baja California and La Paz Bay, Baja California Sur, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025AFFAAFD864F78FAB579FB.taxon	biology_ecology	Habitat Symbiont (found in the mantle cavity of Myrakeena angelica (Rochebrune, 1895), Lottia atrata (P. P. Carpenter, 1864), L. mitella (Menke, 1847), L. dalliana (Pilsbry, 1891) and oysters of the family Ostreidae Rafinesque, 1815).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025AFFAAFD864F78FAB579FB.taxon	discussion	Remarks The genus Zygantroplana was established by Laidlaw (1906), characterized by an oval-elongated body, absence of nuchal tentacles, a common gonopore, and lack of armament in the penis papilla (Laidlaw 1906; Marcus & Harry 1982). Currently, the genus comprises two valid species: Z. verilli Laidlaw, 1906 and Z. ups (Tyler et al. 2006 – 2023). Initially, the genus was placed in the family Leptoplanidae and later transferred by Faubel (1983) to the family Ilyplanidae. However, it is suggested to verify the generic status and family classification of the species, as Marcus & Harry (1982) described the presence of an interpolated granular vesicle (granule vesicle (prostate) = interpolated prostatic vesicle), a character absent in the family Ilyplanidae according to Faubel (1983), as well as an armed penis papilla with a stylet. Additionally, a review of the structure described by Marcus & Harry (1982) as uteri is recommended, as they present a morphology similar to the Lang’s vesicle found in Bivesiculoplana lamothei Pineda-López & González-Bulnes, 1984. It is also advised to conduct a thorough review of the specimens registered by González & Salazar-Vallejo (1996) as Z. ups, as the redescribed features by these authors do not match those of the nominal species.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025BFFAAFD844942FAD77E12.taxon	distribution	Distribution Black Beach, Floreana Island, Santiago Island and south of Seymour Island, Galapagos Archipelago, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025BFFAAFD844942FAD77E12.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025BFFAAFD844942FAD77E12.taxon	discussion	Remarks Hyman (1953 b) initially described the species as Latocestus galapagensis; however, Faubel (1983) transferred it to the genus Eulatocestus based on the morphology of the prostatic vesicle. The latter exhibits a thick glandular coating, consisting of a network of follicles (see Hyman 1953 b: 199, fig. 2); whereas in the genus Latocestus Plehn, 1896, the prostatic vesicle shows a rigid and irregular glandular lining or digitiform (see Hyman 1953 a: 276, fig. 3). Eulatocestus galapagensis has an elongate, grayish-brown body, the body margin surrounded by a band of marginal eyes, cerebro-frontal eyes arranged in two bands, and frontal eyes arranged in a fan-shaped pattern between the brain region and the anterior end. The pharynx is located in the last third of the body. The gonopores are located at the end of the posterior region of the body. The male reproductive system features spermiducal vesicles and spermiducal ducts oriented towards the anterior-posterior region of the body, oval free prostatic vesicle, and an inert conical penis papilla. The female reproductive system features a vagina and an oval Lang’s vesicle, oriented towards the posterior region of the body.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025BFFA9FDA74D9BFDE17BCA.taxon	distribution	Distribution Los Ángeles Bay, Willard Island, San Luis Gonzaga Bay, Ángel de la Guarda Island, Puerto Refugio, Baja California; San Ignacio Lagoon, Puerto Loreto (Puerto Escondido); San Carlos, Guaymas, Sonora; Puerto Peñasco, Sonora; Punta Piaxtla, Sinaloa; El Carrizalillo, Oaxaca, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025BFFA9FDA74D9BFDE17BCA.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025BFFA9FDA74D9BFDE17BCA.taxon	discussion	Remarks Hyman (1953 a) described the species as Alleena mexicana. The genus Alleena was established by Marcus (1947) in the family Latocestidae based on the elongated body shape and the perpendicularly oriented male reproductive system. However, Faubel (1983) considered these characters questionable and insufficient to establish the genus; therefore, he assigns Alleena Marcus, 1947 as a synonym of Latocestus. Latocestus mexicana has an elongated body with gray coloration; a band of marginal eyes distributed in the first third of the body; cerebral eyes, scarce tentacular and marginal eyes distributed in a fan shape; elongated and scarcely branched pharynx positioned in the last third of the body, with the oral opening located in the last third of the pharynx, the main intestine occupying two-thirds of the body and is positioned anterior to the pharynx. The male reproductive tract has spermiducal bulbs, and an oval prostatic vesicle lined with digitiform epithelium and positioned directly above the penis papilla, the latter being inert. The female reproductive system has a short female atrium, a tubular vagina, and a thin, elongated Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380258FFA9FDF04F32FC097E4D.taxon	distribution	Distribution San José, Panama.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380258FFA9FDF04F32FC097E4D.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380258FFA9FDF04F32FC097E4D.taxon	discussion	Remarks Latocestus viridis has an elongated body with rounded anterior and posterior region; dull green coloration, with slight yellowish-green pigmentation in the upper region (often in stripes, in preserved organisms) (see Bock 1913: 64), ventral region with faint pink pigmentation; marginal eyes distributed on the periphery of the whole body, frontal eyes; male reproductive system with spermiducal vesicles and spermathecal ducts; ovoid prostatic vesicle, inert penis papilla, and female reproductive system with an S-shaped vagina, and narrow, sparsely muscular Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380258FFA8FDF94DF6FC5A7AD2.taxon	distribution	Distribution Puerto Peñasco, Sonora, Mexico. Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380258FFA8FDF94DF6FC5A7AD2.taxon	discussion	Remarks Latoplana levis was originally described by Hyman (1953 a) within the genus Mexistylochus Hyman, 1953. Hyman (1955 a) later transferred it to the genus Ommatoplana Laidlaw, 1903, and finally, Faubel (1983) transferred the species to the genus Latoplana. The genus is characterized by a prostatic vesicle lined with a ray-shaped or digitiform epithelium. A revision of the morphology of the reproductive system of L. levis is suggested because some of the characters described (prostatic vesicle and Lang’s vesicle) are similar to those described in the genus Latocestus.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380259FFA8FEC6487CFD597E3F.taxon	distribution	Distribution Agua Blanca Beach, Puerto Escondido, Oaxaca, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380259FFA8FEC6487CFD597E3F.taxon	biology_ecology	Habitat Epibiont (in Padina Adans. – Jellyella Taylor & Monks, 1997).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380259FFA8FEC6487CFD597E3F.taxon	discussion	Remarks Bivesaculosuteri marcelae is characterized by an oval to circular body, cerebral and tentacular eyes, absence of marginal eyes, and pyriform nuchal tentacles. The male reproductive system features a poorly differentiated interpolated prostatic vesicle, an oval and prominent seminal vesicle, spermiducal vesicles, and cylindrical sclerotized stylet with acicular tip. The female reproductive system features a uterine duct, a paired uterine sac, ovoid and strongly muscularized uterine vesicles, a muscularized vaginal pore located posteriorly to the female gonopore, a vaginal duct, an oval Lang’s vesicle, and poorly developed duct of Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380259FFAFFE164D67FAB57B7A.taxon	distribution	Distribution Punta Pérula Beach, Las Rosadas, El Negrito, La Manzanillas, Jalisco; Azul Beach, Michoacán; La Ropa Beach, La Barrita, Guerrero; El Carrizalillo Beach, Agua Blanca, El Aguete, Puerto Ángel, Boca Vieja, Coyula, Oaxaca, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380259FFAFFE164D67FAB57B7A.taxon	biology_ecology	Habitat Ectocomensal (mantle cavity of Fissurella gemmata Menke, 1847, F. decemcostata J. H. McLean, 1970, Lottia pediculus (R. A. Philippi, 1846), L. discors (R. A. Philippi, 1849), Siphonaria G. B. Sowerby I, 1823 and Ancistromesus mexicanus (Broderip & G. B. Sowerby I, 1829 )).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380259FFAFFE164D67FAB57B7A.taxon	discussion	Remarks Bivesiculoplana lamothei is a Leptoplanidae ectocomensal of gastropods, characterized by an oval body with a granular dorsal surface (subepidermal), digitiform or circular nuchal tentacles, cerebral and tentacular eyes lack of marginal eyes, and an elongate and sparsely branched pharynx. Gonopores are separate; the male reproductive system features an oval sparsely muscled seminal vesicle, and a sclerotized filiform stipe; the female reproductive tract features paired fusiform Lang’s vesicles and a heavily muscled vagina.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025EFFAFFD9348A3FAE67F5A.taxon	distribution	Distribution La Paz Bay, Baja California Sur, and pelagic environment in the Gulf of California and off the coast of Sinaloa, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025EFFAFFD9348A3FAE67F5A.taxon	biology_ecology	Habitat Pelagic obligate.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025EFFAFFD9348A3FAE67F5A.taxon	discussion	Remarks Due to the presence of the species in the pelagic habitat, Woodworth (1984) and Faubel (1984 a) determined Leptoplanella californica as a pelagic obligate species. Woodworth (1894) originally described the species as Stylochoplana californica, based on immature organisms, characterizing the external morphology of the body and scarcely the internal morphology of the species; Woodworth described a cuneiform body, the presence of nuchal tentacles, a short penis papilla and a bursa copulatrix (= Lang’s vesicle). Subsequently, Hyman (1953 a) made a redescription of the species and reassigned it to the genus Parviplana as Parviplana californica, based on the length of the body, the arrangement of the eyes and the external morphology of the reproductive complex. Subsequently, Faubel (1984 b) reassigned the species to the genus Leptoplanella, and made a complete redescription of the external and internal morphology of the male and female reproductive systems, in which he determined the presence of a penis papilla armed with a sclerotized and conspicuous stipe, as well as the seminal vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025FFFAEFDAF4A5AFBE17BF4.taxon	distribution	Distribution Bahía de los Ángeles, Baja California.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025FFFAEFDAF4A5AFBE17BF4.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025FFFAEFDAF4A5AFBE17BF4.taxon	discussion	Remarks Longiprostatum rickettsi is a species characterized by tentacular, cerebral, frontal, and marginal groups of eyes distributed only in the anterior region of the body, a very long and narrow prostatic vesicle, with a sclerotized diaphragm separating its lumen from that of the penis papilla and with a sclerotic lining and seminal vesicle and Lang’s vesicle, both of which are present but reduced.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025FFFAEFDCC4F3CFBB97F66.taxon	distribution	Distribution Newport Bay and Tomales Haed, Marin Country, California; Gulf of California, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025FFFAEFDCC4F3CFBB97F66.taxon	biology_ecology	Habitat Benthic (on a rocky shore, among a mass of sponge and bryozoans).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025FFFAEFDCC4F3CFBB97F66.taxon	discussion	Remarks Parviplana hymani lacks nuchal tentacles, has an ejaculatory duct through the prostatic vesicle, and has a bulbous vagina. In the WoRMS database, Parviplana californica is listed as a junior synonym of Parviplana hymani and Leptoplanella californica (= Stylochoplana californica). However, this classification is not correct. Hyman (1953 a) described a new genus, Parviplana, and moved Leptoplanella californica (= Stylochoplana californica) into this genus, creating the combination Parviplana californica. In the same publication, a new specimen was also described under that name. However, Faubel (1983) proposed a new specific epithet, Parviplana hymani, which invalidated the synonyms Parviplana californica and Stylochoplana californica for this species.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025CFFADFE7A4A7DFC797C1E.taxon	distribution	Distribution Santa Cruz Island, Galapagos Archipelago, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025CFFADFE7A4A7DFC797C1E.taxon	biology_ecology	Habitat Interstitial (coarse intertidal sediments) or rocks.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025CFFADFE7A4A7DFC797C1E.taxon	discussion	Remarks Mucroplana caelata could be considered a very primitive species because the most unique organizational feature within the polyclads: the proximal concentration of the extraepithelial prostatic glands. The family Mucraplanidae is characterized by the absence of a true prostatic vesicle, but it presents a peculiar structure in the distal ejaculatory duct, which expands to form a bulbous organ. This organ can assume the function of a seminal vesicle by storing sperm (Faubel 1983).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025CFFADFDBC4FA9FB137FF0.taxon	distribution	Distribution Portuguese Bend, California; San Ignacio Lagoon, Baja California Sur, Miramar Beach, Guaymas; San Carlos Bay, Sonora, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025CFFADFDBC4FA9FB137FF0.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025CFFADFDBC4FA9FB137FF0.taxon	discussion	Remarks Notocomplana mexicana is characterized by marginal eyes distributed in the first third of the body, cerebro-tentacular eyes, and a pharynx oriented towards the anterior region of the body. Its reproductive system features a seminal vesicle and a tubular prostatic vesicle, spermiducal ducts and vesicles, short penis papilla, and elongated Lang’s vesicle oriented towards the posterior region of the body. Hyman (1953 a) described the species as Phaenocelis mexicana; while Faubel (1983) transferred the species to the genus Notocomplana; however, he did not establish the criteria for this reassignment.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025DFFACFE7E4A18FBB27CC5.taxon	distribution	Distribution Monterey Bay, McGinities, Huntington Beach, California Pacific Grove, La Paz Bay, Baja California Sur.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025DFFACFE7E4A18FBB27CC5.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025DFFACFE7E4A18FBB27CC5.taxon	discussion	Remarks Heath & McGregor (1912) made the first description of the species, determining it as Leptoplana saxicola; later Hyman (1953 a) transferred the species to the genus Notocomplana based on the presence of a prominent vesicle. The present study suggests an exhaustive revision of the organisms described by these authors, due to the variants in the position and morphology of Lang’s vesicle and the orientation of the pharynx, described below: 1. The organisms described by Heath & McGregor (1912) have an oval Lang’s vesicle positioned anterior to the female gonopore and oriented toward the anterior region of the body; and a pharynx oriented toward the posterior region of the body (Heath & McGregor 1912: pl. 12 fig. 4; pl. 16 fig. 30). 2. Specimens described by Hyman (1953 a) have an oval Lang’s vesicle positioned posterior to the female gonopore and oriented toward the posterior region of the body; and a pharynx oriented toward the anterior region of the body (Hyman 1953 a: 316, 320, figs 66, 68).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025DFFA3FDA64E6FFDFA7B51.taxon	distribution	Distribution Central America, off the coast of Oaxaca; the Red Sea, the Indian Ocean, the northern and southern regions of the Atlantic Ocean in the northern and southern region of the latter, and the Pacific Ocean.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025DFFA3FDA64E6FFDFA7B51.taxon	biology_ecology	Habitat Pelagic and symbiont (occupies the mantle cavity of Janthina janthina (Linnaeus, 1758) (Faubel et al. 2007: 429 )), preferably in 18 ° C water mass.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38025DFFA3FDA64E6FFDFA7B51.taxon	discussion	Remarks Faubel (1983) redescribed the species from samples belonging to the neuston, collected in the Red Sea and the central and southern region of the Atlantic Ocean. The species is characterized by a translucent elongated body with a light yellowish-brown granular pigmentation on the dorsal region, cerebral and tentacular eyes, the latter distributed in the periphery (only in the internal region) of the nuchal tentacles, and central pharynx with an oral opening located at the end of the last third of the pharynx. The male reproductive system has spermiducal vesicles, spermiducal bulbs, a seminal vesicle and a prostatic vesicle, and a cirrus sac armed with sclerotial spines. The female reproductive system has a bulbous vagina and lacks Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380252FFA3FDD34897FE5F7E2A.taxon	distribution	Distribution Gardner Bay, Española Island, Galapagos Archipelago, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380252FFA3FDD34897FE5F7E2A.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380252FFA3FDD34897FE5F7E2A.taxon	discussion	Remarks The species is characterized by a circular body with indeterminate, apparently translucent dorsal coloration, cerebral eyes distributed in two groups and arranged in a line, and tentacular eyes located at the base of the conspicuous nuchal tentacles; central pharynx scarcely folded; male reproductive system features an elongate oval seminal vesicle, an ovoid prostatic vesicle, and a cirrus sac armed with small spines and three conspicuous teeth. The female reproductive system features a muscular female atrium with a scalloped tissue of sclerotized appearance, and a elongate vagina oriented towards the anterior region of the body.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380252FFA2FE264D90FECB7C83.taxon	distribution	Distribution Playa Langosta Beach, Las Baulas National Marine Park of Guanacaste, Costa Rica.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380252FFA2FE264D90FECB7C83.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380252FFA2FE264D90FECB7C83.taxon	discussion	Remarks Prudhoe (1945: 197 – 198, figs 1 – 2) divided the genus into two groups based on the internal morphology of the male reproductive system and thereby reduced the genus to three species (P. oligoglena (Schmarda, 1859), P. aurora Laidlaw, 1903, and P. marginata Meyer, 1922), these groups were characterized by the following characters: Group 1: Cirrus cavity lined with numerous spines (comparatively they are largest near the male atrium); the spermiducal duct (= the seminal vesicle canals) opens into the ventral wall of the prostatic vesicle. Group 2: Cirrus cavity lined with numerous small spines with a pair of conspicuous sclerotized projections (teeth); the spermiducal duct opens into the prostatic duct just before entering the cirrus sac. However, Hyman (1955 b) and Faubel (1983) considered the criteria proposed by Prudhoe (1945) for species reduction to be inadequate. They argued that these criteria lacked a thorough review of characters, presented unsatisfactory descriptions, and omitted certain features, in particular the presence or absence of accessory prostatic vesicles and the glandular pouch of the male atrium. The latter character was used by Kato (1936) to divide the species of the genus into two groups (Prudhoe 1945). Consequently, Faubel (1983) validated ten species for the genus (P. oligoglena, P. aurora, P. discus (Willey, 1897), P. fritillata Hyman, 1959, P. langii angi (Laidlaw, 1902), P. marginata, P. misakiensis Yeri & Kaburaki, 1918, P. oceanica (Hyman, 1953), P. rotumanensis Laidlaw, 1903 and P. rubrisfasciata Kato, 1937). Recently, two new species have been added: Paraplanocera angeli (Soutullo et al. 2021) and Paraplanocera oligoglenoides (Ramos-Sánchez et al. 2019); however, the present study suggests a detailed review of the existing biological material for the described species in the genus together with the re-evaluation of each of the characteristics that define the species. Paraplanocera angeli has a translucent coloration pattern, a cirrus sac that lacks sclerotized adenoids, and a smooth, ciliated Lang’s vesicle (Soutullo et al. 2021).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380253FFA1FDB04FCAFD417977.taxon	distribution	Distribution Tagus Cove, Isabela Island, Galapagos Archipelago, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380253FFA1FDB04FCAFD417977.taxon	biology_ecology	Habitat Benthic (sandy bottom).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380253FFA1FDB04FCAFD417977.taxon	discussion	Remarks Paraplanocera oceanica was described by Hyman (1953 b) as Aquaplana oceanica. Hyman does not include it in the genus Paraplanocera due to the presence of an elongated cirrus papilla. However, Faubel (1983) proposed that the morphology of this structure could be due to the organisms having been fixed after a copulation process (because during copulation, the cirrus protrude through the male gonopore) and that this structure is a proper elongation of the cirrus sac (see Faubel 1983: 76); therefore, Faubel transferred the species to the genus Paraplanocera, citing additional characteristics such as the presence of a prominent Lang’s vesicle, a bursa copulatrix, absent seminal vesicle, and nuchal tentacles. Paraplanocera oceanica has a cirrus sac with an elongated penis papilla that is armed with small spines in the terminal region (Hyman 1953 b).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380250FFA1FD894A7DFC417F46.taxon	distribution	Distribution Pantropical distribution. Sri Lanka, Christmas Island, Quobba Beach, Australia, archipelagos of Polynesia, Micronesia and Melanesia; Hilo, Hawaii, west coast of Japan. On the Mexican Pacific coast, it has been recorded in the Coronado Islands, Baja California; Punta San Marcial reef, La Paz Bay, Baja California Sur and Miramar Beach, Sonora, Mexico; Carbón Beach in Las Baulas National Marine Park of Guanacaste, Costa Rica. Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380250FFA1FD894A7DFC417F46.taxon	discussion	Remarks Paraplanocera oligoglena has been recorded from the Indo-West Pacific (Schmarda 1859; Stummer-Traunfels 1933; Hyman 1954, 1955 a; Prudhoe 1978; Ken-Ichi et al. 1991). In the Mexican Pacific, P. oligoglena has been recorded from Isla Coronado, Baja California; Punta San Marcial reef, Baja California Sur and Playa Miramar, Sonora (Hyman 1953 a; Brusca 1980; Lamothe-Argumedo et al. 1997); it has also been recorded from Carbon Beach, in Las Baulas National Marine Park of Guanacaste, Costa Rica (Soutullo et al. 2021), therefore it is considered a circumtropical species. Paraplanocera oligoglena was described by Schmarda (1859), as Stylochus oligoglenus, Planocera amphibola, Stylochus amphibolus. Later Stummer-Traunfels (1933) made a revision of the specimens described by Schmarda (1859) under these taxa, establishing them as Paraplanocera oligoglena. The species is characterized by an oval body with smooth dorsal coloration brown, cerebral eyes and tentacular eyes, surrounding the base of the nuchal tentacles, and a pharynx with four or five lobes. The male reproductive system features a prostatic vesicle, ducts and paired spermiducal bulbs, accessory prostatic vesicles, a cirrus sac armed with spines and a pair of conspicuous teeth, and a male atrium with a glandular pouch. The female reproductive system features a bulbous vagina, a short female atrium, an elongate oval bursa copulatrix oriented towards the anterior region of the female gonopore, with a thick muscular wall and posteriorly presenting a very scalloped lining, and an elongate Lang’s vesicle oriented towards the anterior region of the female gonopore.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380251FFA0FEDF4A18FBB07BC1.taxon	distribution	Distribution Agua Blanca, Camarón, Panteón and Puerto Ángel Beaches and in Cacaluta Bay, Oaxaca. This is the first record of the genus from the southern Mexican Pacific.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380251FFA0FEDF4A18FBB07BC1.taxon	biology_ecology	Habitat Benthic, littoral to sublittoral (12 m); under rocks, associated with encrusting bryozoans, green seaweed and chitons.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380251FFA0FEDF4A18FBB07BC1.taxon	discussion	Remarks Paraplanocera oligoglenoides differs from P. oligoglena in the dorsal coloration pattern, the number of cerebral eyes, the intramuscular content of the surrounding spaces of the cirrus sac cavity, the epithelium of the accessory prostatic vesicle, and the orientation, position and morphology of the vagina and bursa copulatrix (see discussion of Ramos-Sánchez et al. 2019). Paraplanocera oligoglenoides has a cirrus sac with spines distributed throughout the sac, paired conspicuous teeth, and lacks a penis papilla. It’s Lang’s vesicle is situated dorsal to the bursa copulatrix (sagittal view). The species also features a folded-elongate pharynx, with the mouth situated in the last third of the pharynx.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380251FFA7FDDE4F4AFC567976.taxon	distribution	Distribution Pardita Island, La Paz Bay, Baja California Sur, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380251FFA7FDDE4F4AFC567976.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380251FFA7FDDE4F4AFC567976.taxon	discussion	Remarks Spinicirrus inequalis is characterized by an elongated body with a rounded anterior end, cerebral eyes arranged in two groups and distributed in a rounded shape and tentacular eyes distributed in two continuous bands; without nuchal tentacles. The male reproductive system lacks bulbs and spermiducal vesicles, presents a cirrus sac armed with teeth; in sagittal view, a glandular pouch is observed positioned in the anterior region of the spermiducal vesicles, with teeth distributed in two groups: a pair in the region posterior to the glandular pouch and approximately two pairs in the region anterior to the male atrium (Hyman 1953 a: 352, fig. 117); in ventral view, these spines are distributed in two groups: one formed by a pair of teeth and the second group presents a total of 15 teeth (Hyman 1953 a: 352, fig. 116). The species also has an oval digitiform prostatic vesicle. The female reproductive system presents a dorsally positioned vagina without Lang’s vesicle. Hyman (1953 a) schematized an elongated sac anterior to the vagina, however, the functionality of this structure is unknown. Hyman (1953 a) suggested collecting more specimens to better define the specific composition of the reproductive system of the species, as well as its systematic position within the family Planoceridae.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380256FFA7FDBE4AC2FBF67C85.taxon	distribution	Distribution Cabo San Lucas, Baja California Sur, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380256FFA7FDBE4AC2FBF67C85.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380256FFA7FDBE4AC2FBF67C85.taxon	discussion	Remarks The species is characterized by an oval-oblong body. It has 20 – 26 cerebral eyes distributed in two lines towards the region anterior to the tentacular eyes, which are distributed circularly; it has 20 – 25 tentacular eyes and lacks nuchal tentacles. The male reproductive system features a bulbous seminal vesicle, a pyriform prostatic vesicle, and a short and inert conical penis papilla. The female reproductive system features an asymmetrical female gonopore positioned to the left of the central axis of the body (position based on the scheme proposed by Hyman 1953 a: 360, fig. 127), a moderately long female atrium, a narrow Lang’s duct, and an elongate, deeply lobed Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380256FFA6FDB14E0EFC287A91.taxon	distribution	Distribution Cabeza Ballena Point, Baja California Sur, Miramar Beach, Guaymas, Sonora, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380256FFA6FDB14E0EFC287A91.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380256FFA6FDB14E0EFC287A91.taxon	discussion	Remarks Ommatoplana mexicana was described by Hyman (1953 a) as Mexistylochus tuberculatus. However, through a comprehensive review of the reproductive system of two specimens from Saipan Island, Northern Mariana Islands (western Pacific), Hyman (1955 a, 1955 b) determined that these specimens were assignable to the genus Ommatoplana, and that Mexistylochus is synonymous to Ommatoplana. Initially Hyman (1953 a) did not place the species within the genus Ommatoplana because the original specimen was incomplete. Ommatoplana mexicana is characterized by an oval body with brown dorsal coloration, with white blunt-ended protuberances (tubercles); marginal eyes distributed throughout the body margin, cerebral eyes, frontal eyes, and tentacular eyes arranged in a circular fashion and with approximately 30 eyes each. The elongate pharynx occupies two-thirds of the body and has approximately 20 pharyngeal lobes. The male reproductive system features a tripartite seminal vesicle, a prominent oval prostatic vesicle located horizontally to the seminal vesicle and an inert conical penis papilla protected by a penis sheath. The female reproductive system features a muscular ductus vaginalis with scalloped inner walls and a pore posterior to the female gonopore, a tubular female atrium, and an elongated vagina oriented towards the posterior region of the body and Lang’s vesicle is absent.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380257FFA6FE59483DFD757DFF.taxon	distribution	Distribution Playa Carbón, Las Baulas National Marine Park of Guanacaste, Costa Rica.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380257FFA6FE59483DFD757DFF.taxon	biology_ecology	Habitat Benthic, low intertidal, under stones and sand.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380257FFA6FE59483DFD757DFF.taxon	discussion	Remarks Cryptostylochus currently comprises four species: C. coseirensis (Bock, 1925), C. hullensis Faubel & Gollasch, 1996, C. koreensis Bulnes, Faubel & Park, 2005 and C. sesei. Cryptostylochus sensei has a dark yellow background color densely mottled with orange. It features nuchal tentacles at the end of the first third of the body, and cerebral and tentacular eyes. The male reproductive system contains a muscular seminal vesicle, a monoglandular prostatic vesicle, and a penis papilla housed in a welldeveloped heart-shaped atrium. The female reproductive system consists of an internal vagina and an external vagina, but lacks a Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380257FFA5FE0E4D28FD677A77.taxon	distribution	Distribution San Blas Nayarit, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380257FFA5FE0E4D28FD677A77.taxon	biology_ecology	Habitat Symbiont (mantle cavities of Crassostrea corteziensis (Hertlein, 1951 )).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380257FFA5FE0E4D28FD677A77.taxon	discussion	Remarks Imogine mexicanus is characterized by an ovoid body. In vivo the species exhibits greenish-brown coloration with black pigments distributed homogeneously in the dorsal region; ventrally it is light brown with a reddish halo towards the posterior end of the body denoting the female genital pore. Postfixation the dorsal coloration becomes grayish with black dots. The species has cerebral eyes, marginal eyes distributed throughout the periphery of the body, and tentacular eyes distributed at the base of the conspicuous nuchal tentacles. The male reproductive system features an elongate tripartite seminal vesicle, an ovoid prostatic vesicle, and an inert penis papilla protected by a penis sheath. The female reproductive system has a tubular vagina.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380254FFA5FF4249A0FED47DA8.taxon	distribution	Distribution Tropical Eastern Pacific. Central coast of Oaxaca: Tangolunda Bay, Bahías de Huatulco, Oaxaca.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380254FFA5FF4249A0FED47DA8.taxon	biology_ecology	Habitat Fouling. The polyclads were found inside the shells of Paraconcavus pacificus (Pilsbry, 1916), which were part of the fouling of a marine sensor (SeapHOx ®), at a depth of approximately 20 – 25 m.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380254FFA5FF4249A0FED47DA8.taxon	discussion	Remarks Stylochus mistus has a beige background color with scant orange to light brown pigmentation, and black transverse spots which, when fused, give the appearance of lines, mainly in the anterior marginal region of the body. The nuchal tentacles are orange, and the body margin is orange or pink. The species has marginal, tentacular, and cerebral eyes. Its gonopores are separated. The male reproductive system features prominent prostatic vesicle, which is oval, and polyglandular, an elongayed and prominent seminal vesicle, and a short the penis papilla. The female reproductive system features a scarcely developed, narrow, and short vagina, oriented towards the anterior region of the body, and lacks a Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380254FFA4FDD54EAFFB54795A.taxon	distribution	Distribution From Coos Bay, Oregon, to El Mogote, Baja California Sur.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380254FFA4FDD54EAFFB54795A.taxon	biology_ecology	Habitat Epibiont and benthic (kelp rhizoids and under shore rocks).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380254FFA4FDD54EAFFB54795A.taxon	discussion	Remarks Stylochus tripartitus is characterized by a light brown coloration covered with brown streaks, marginal eyes distributed in the first third of the anterior region of the body, tentacular and cerebral eyes, and nuchal tentacles. The male reproductive system features a tripartite seminal vesicle and a small penial papilla. The female reproductive system lacks a Lang’s vesicle. Stylochus tripartitus is one of the two Californian species of the genus Stylochus with a tripartite seminal vesicle. The other species is S. exiguus Hyman, 1953, which is very small and has marginal eyes that surround the body margin. Stylochus tripartitus differs from S. mistus primarily in color and coloration pattern.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380255FFA4FE774AC2FE227DB9.taxon	distribution	Distribution San Mateo, Charleston, Cape Arago State Park, Oregon; San Nicolas Island, California, United States; San Lorenzo Channel, La Paz Bay, Baja California Sur, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380255FFA4FE774AC2FE227DB9.taxon	biology_ecology	Habitat Benthic (collected in rocky hollows in San Mateo, California, at a depth of 51.2064 m on San Nicolas Island, California; between 5.48 and 9.11 m in the San Lorenzo Channel, Gulf of California; in the intertidal zone in Oregon).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380255FFA4FE774AC2FE227DB9.taxon	discussion	Remarks Stylochus (Stylochus) atentaculatus is characterized by an elongate oval body with a dark brown coloration with dots, marginal eyes distributed throughout the periphery of the body, cerebral eyes arranged in two lines and tentacular eyes distributed in a circular manner, and round nuchal tentacles. Hyman (1953 a) described that the nuchal tentacles is only present in juveniles and in adult organisms this character is not observed; Hyman considered that in adult specimens the tentacles are fused with the dorsal surface. The male reproductive system features a simple (not tripartite) an elongated seminal vesicle, a prominent oval prostatic vesicle; wide male atrium. The female reproductive system has a tubular female atrium, an elongated and prominent vagina, with the central region of the vagina characterized by a highly scalloped muscular wall.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380255FF9BFDCF4D04FD6779A7.taxon	distribution	Distribution Paita, Piura, Peru (5 ° 4 ʹ 12.45 ″ S, 81 ° 8 ʹ 50.96 ″ W) (sensu Reyes et al. 2020).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380255FF9BFDCF4D04FD6779A7.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380255FF9BFDCF4D04FD6779A7.taxon	discussion	Remarks Alloioplana delicata has nuchal tentacles, and cerebral and tentacular eyes. The male reproductive system features a seminal vesicle, and a penis papilla armed with a long and pointed stylet. The female reproductive system lacks Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026AFF9BFDD84AAEFC907CD8.taxon	distribution	Distribution Puerto Refugio, Ángel de la Guardia Island, Baja California; Tiburón Island, Sonora, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026AFF9BFDD84AAEFC907CD8.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026AFF9BFDD84AAEFC907CD8.taxon	discussion	Remarks Alloioplana stylifera was initially described by Hyman (1953 a) within the genus Zygantroplana, while Faubel (1983) transferred it to the genus Alloioplana, based on the presence of separate gonopores, a seminal vesicle, an interpolated prostatic vesicle, an armed penis papilla, and Lang’s vesicle. Alloioplana stylifera is characterized by an oblong body with a truncated posterior end, absence of nuchal tentacles, presence of cerebro-tentacular eyes, an elongated pharynx, and separate gonopores located in the terminal region of the body. The seminal vesicle are rudimentary, the penis papilla is armed with a thin and prominent stylet (in proportion of the same size as the vagina), the elongated tubular vagina is oriented towards the posterior-dorsal region of the body.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026AFF9AFDB24E41FED97B26.taxon	distribution	Distribution Southern California to southern Gulf of Panama. Santa Barbara Island, Catalina Island, Newport Harbor, California; Guaymas, Sonora, Mexico and Gulf of Panama.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026AFF9AFDB24E41FED97B26.taxon	biology_ecology	Habitat Benthic and fouling (rocks, sandy bottom at 73.152 m depth off Santa Catalina Island and on floating pilings and buoys in Newport Harbor, California).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026AFF9AFDB24E41FED97B26.taxon	discussion	Remarks Plehn (1896) described the species, whose type locality is the Gulf of Panama. Later, Hyman (1953 a) recorded it in California and Guaymas, Sonora, Mexico. Hyman (1953 a) observed morphological and size variations in the seminal vesicle, prostatic vesicle, and the distance between the ejaculatory duct and the seminal vesicle; however, she determined these differences as a possible intraspecific variation and assigned the specimens to A. panamensis based on the arrangement and distribution of the eyes, the presence of a long-curved stipe, and an elongated Lang’s vesicle, described in the nominal species. The present study, based on the revision and comparison of the diagnoses and schemes made by Plehn (1896) and Hyman (1953 a), found a difference in the coloration pattern of the species. Plehn (1986) described a dark grayish-brown coloration with a pattern composed of three dark longitudinal lines (Plehn 1986: figs 3, 10 – 11). This pattern was not observed or described in the specimens of Hyman (1953 a), who mentions a grayish dorsal coloration. In addition to the morphological variations previously determined by Hyman (1953 a), we suggest an exhaustive review of the material described by both authors.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026BFF9AFD92486EFAAB7F8D.taxon	distribution	Distribution Galapagos Archipelago, Ecuador; Taboga and Taboguilla Islands, Panama; Gilbert Islands, Kiribati, Indian Ocean.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026BFF9AFD92486EFAAB7F8D.taxon	biology_ecology	Habitat Ectocomensal (associated with the shell of Petrochirus californiensis Bouvier, 1895).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026BFF9AFD92486EFAAB7F8D.taxon	discussion	Remarks Emprosthopharynx opisthoporus is a species characterized by a translucent yellow coloration with a brownish body margin (postfixation coloration), cerebral, tentacular and submarginal eyes, the latter distributed in the first third of the body. The pharynx is located in the first third of the body, oriented towards the anterior region. The separate gonopores are positioned in the last third of the body. The male reproductive system features an oval seminal vesicle and an interpolated prostatic vesicle oriented towards the anterior region of the body, and a conical, short and inert penis papilla. The female reproductive system has a vagina oriented towards the posterior region of the body (it is worth mentioning that the female structures of the species were not fully developed). Emprothopharynx opisthoporus was described by Bock (1913) and collected as a free-living species, which shares substrate with Petrochirus californiensis in the Galapagos Archipelago. Subsequently, it was later recorded in Panama associated with the shell of P. californiensis on Taboga Island; Emprothopharynx opisthoporus are located on the sand and in the Taboguilla Islands on the same pagurid at 9 m depth; he determined the association as ectocommensalism, he observed that the polyclad lodges in the cavity of the shell, to move away from the light and seek protection; later Bock (1913) recorded the species in the Gilbert Islands; however, he did not make a detailed description of the specimens (Prudhoe 1968).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380268FF99FDBE4A18FDFA7DC2.taxon	distribution	Distribution Hawaiian Islands and between the María Madre and Isabela Islands, Nayarit, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380268FF99FDBE4A18FDFA7DC2.taxon	biology_ecology	Habitat Symbiont (Calcinus latens (Randall, 1840 )).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380268FF99FDBE4A18FDFA7DC2.taxon	discussion	Remarks Emprosthopharynx rasae was collected on shells of Trochus intextus Kiener, 1850 occupied by the hermit crab Calcinus latens. The worm is found around the abdomen of the pagurid, usually in the spiral cavity of the shell. The frequency of occurrence of the association is about one per 25 – 30 pagurids. Emprosthopharynx rasae differs from E. opisthoporus in dorsal coloration, distribution of submarginal eyes, and morphology of the seminal vesicle. Prudhoe (1968) described the species in the Hawaiian Islands, noting its reddish-brown coloration with light margins and slight specks and spots that appear to be ovaries distributed under the body wall, a lack of nuchal tentacles, a prsence of submarginal eyes distributed throughout the body, sparse cerebral and tentacular eyes, a sparsely folded pharynx located immediately posterior to the brain, and gonopores separated and positioned in the last third of the body. The male reproductive tract features a seminal vesicle and pyriform prostatic vesicle oriented towards the anterior region of the body, anda a short inert penis papilla. The female reproductive tract has a bulbous vagina oriented towards the posterior region of the body and lacks Lang’s vesicle. Pineda-López (1981) recorded the species in the islands of Nayarit, Mexico (Lamothe-Argumedo et al. 1997), associated with a pagurid at a depth between 80 and 90 m. However, this author suggests a revision of more organisms because in his specimen he found variations in the size of the pharynx, and in the number of cerebral eyes, and he did not revise the male and female reproductive system of the specimens recorded for Nayarit.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380268FF98FDA84D4BFB5F7C22.taxon	distribution	Distribution Corona del Mar, San Diego Bay, La Jolla, California; Punta Marcial reef, Baja California Sur; Puerto Peñasco, Sonora, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380268FF98FDA84D4BFB5F7C22.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380268FF98FDA84D4BFB5F7C22.taxon	discussion	Remarks Interplana sandiegensis was initially included in the genus Planocera characterized by the absence of a seminal vesicle, Hyman (1953 a) later transferred it to the genus Alloioplana. However, as Alloioplana is characterized by the absence of nuchal tentacles and Lang’s vesicle, Faubel (1983) subsequently transferred the species to the genus Interplana. Interplana sandiegensis has a light brown coloration and dark brown spots, with an olive-green variant in some specimens; an oval body rounded anteriorly and slightly pointed posteriorly, nuchal tentacles, tentacular and cerebral eyes, and a pharynx located in the central region of the body, slightly oriented towards the anterior region of the body. The male reproductive system features an elongated oval seminal vesicle, an oval interpolated prostatic vesicle, and a cirrus sac armed with elongated sclerotized teeth located in the dorsal and ventral region of the cirrus (Hyman 1953 a: 348, fig. 112). Faubel (1983) described this structure as a complex feature of the penis papilla (“ complicated armed penis stylet ”) and named it a stylet. The female reproductive system has a bulbous vagina positioned anterior to the female gonopore and a tripartite Lang’s vesicle positioned posterior to the female gonopore.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380269FF9FFDB44F68FAB579C0.taxon	distribution	Distribution Point Fermin, San Pedro, California, Santa Catalina Island, Newport Bay, California, United States; Miramar Beach, Sonora, Mexico (southern California to southern Gulf of California).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380269FF9FFDB44F68FAB579C0.taxon	biology_ecology	Habitat Benthic and epibiont (found on rocky shores of Miramar beach; as epibionts of Cladophora Kütz. seaweed populations and in the rhizoids of phaeophyte seaweed (kelp )).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380269FF9FFDB44F68FAB579C0.taxon	discussion	Remarks Initially, P. longipenis was described by Hyman (1953 a) in the genus Stylochoplana. Later, Faubel (1983) proposed the genus Phaenoplana and transferred the species to this genus. The characters Faubel (1983) proposed for the separation of the genera are: a conical penis papilla and a rudimentary oval Lang’s vesicle for Stylochoplana, and a rod-like penis papilla and a horseshoe-like Lang’s vesicle for the genus Phaenoplana. However, P. longipenis presents an elongated cylindrical penis papilla (which by morphology could be considered rod-like) and an elongated oval Lang’s vesicle (different from a horseshoe-like shape). Based on this discrepancies, the present study suggests a complete revision and analysis of the characters that define both genera. Phaenoplana longipenis has an elongated body, with rounded anterior and posterior terminal region, grayish dorsal coloration, cerebral and tentacular eyes present, and a central pharynx oriented slightly towards the anterior region of the body. The male reproductive tract features seminal vesicle and an interpolated prostatic vesicle, the latter with an elongated tubular morphology forming a pronounced V-shaped curvature, and an inert elongated cylindrical penis papilla, structures oriented towards the anterior region of the body. The female reproductive tract has a bulbous vagina, elongated Lang’s duct and a prominent elongated oval an Lang’s vesicle, all oriented towards the posterior region of the body.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026EFF9FFE61496BFC747D96.taxon	distribution	Distribution James Bay and Caleta Negra (Curini-Galletti et al. 2008), Fernandina, Isabela, Genovesa, Bartholomew, San Cristobal, Hood and Santa Cruz Islands, Galapagos, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026EFF9FFE61496BFC747D96.taxon	biology_ecology	Habitat Interstitial.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026EFF9FFE61496BFC747D96.taxon	discussion	Remarks Theama occidua was originally described by Sopott-Ehlers & Schmidt (1975). Subsequently, Faubel (1983) established the genus Eutheama and determined T. occidua as the type species, based on an unarmed penis papilla; however, Curini-Galletti et al. (2008) conducted a detailed review of the reproductive system of the species and observed the presence of a small sclerotized area in the internal ejaculatory duct. Based on this character, they transferred the species back to the genus Theama and established Eutheama as a junior synonym of the genus Theama.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026EFF9EFEE74D45FDE07B99.taxon	distribution	Distribution Central coast of Oaxaca: Agua Blanca, San Agustinillo, Panteón, Estacahuite Beaches and Cacaluta Bay. This is the first record of the genus for the Tropical Eastern Pacific.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026EFF9EFEE74D45FDE07B99.taxon	biology_ecology	Habitat Benthic, littoral to sublittoral (2 – 10 m). Specimens of Boninia were collected under rocks, frequently in tide pools, in groups of three to six specimens on each rock and alongside chitons and seaweeds.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026EFF9EFEE74D45FDE07B99.taxon	discussion	Remarks Boninia oaxaquensis is assigned to the genus Boninia based on prostatoid organs symmetrically surrounding the male gonopore. Boninia oaxaquensis presents 14 – 66 (n = 24, μ = 36, SD = 26) cerebral eyes and 36 – 126 (n = 24, μ = 78, SD = 45) marginal eyes, has between 16 – 24 (n = 24) prostatoid organs arranged in one girdle, and its habitat is in the littoral to sublittoral zone (2 – 10 m), under rocks in tide pools and sublittoral rocks. Currently, the genus comprises seven valid species B. antillarum (Hyman 1955 c), B. divae Marcus & Marcus, 1968, B. mirabilis Bock, 1923, B. neotethydis Curini-Galletti & Campus, 2007, B. oaxaquensis, B. uru Tsuyuki, Oya & Kajihara 2022, and B. yambarensis Tsuyuki, Oya & Kajihara 2022. Authors such as Bock (1923), Hyman (1955 a), Marcus & Marcus (1968), Curini-Galletti & Campus (2007), and Ramos-Sánchez et al. (2020) have suggested that the key diagnostic characters for defining species within the genus are: the number of prostatoid organs, the arrangement and number of their girdles, which are distributed on each side of the penis papillae, the distribution and number of cerebral eyes and marginal eyes, and the habitat.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026FFF9EFE4548C0FAC17DF2.taxon	distribution	Distribution Playa Carbon and Playa Langosta, Las Baulas National Marine Park of Guanacaste, Costa Rica.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026FFF9EFE4548C0FAC17DF2.taxon	biology_ecology	Habitat Benthic, one of the most abundant genera in the intertidal zone of the park.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026FFF9EFE4548C0FAC17DF2.taxon	discussion	Remarks Soutullo et al. (2021) recorded Boninia sp. on the basis of external morphology and coloration pattern; however, because the specimens were damaged, they were unable to make a specific identity.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026FFF9DFE684EFAFC5C798B.taxon	distribution	Distribution Fernandina, Isabela, Santa Cruz, Floreana Islands, Galapagos Archipelago, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026FFF9DFE684EFAFC5C798B.taxon	biology_ecology	Habitat Interstitial (intertidal zone coarse sediment).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026FFF9DFE684EFAFC5C798B.taxon	discussion	Remarks Traunfelsia sp. was described by Sopott-Ehlers & Schmidt (1975). Westheide (1991) conducted a study of the invertebrate meiofauna in the Galapagos archipelago, where he recorded the presence of the species as part of the interstitial fauna. However, he did not make a complete description of the organisms, limiting his determination only to the generic level.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026CFF9DFE5E4956FCC07C92.taxon	distribution	Distribution Playa Langosta, Las Baulas National Park of Guanacaste, Costa Rica.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026CFF9DFE5E4956FCC07C92.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026CFF9DFE5E4956FCC07C92.taxon	discussion	Remarks Prostheceraeus fitae has white and black stripes with a yellow central line, a much more delicate stipe compared to other species in the genus, and a long and narrow male atrium. The genus Prostheceraeus currently comprises 19 valid species, most of them distributed in the North Atlantic and Mediterranean (Soutullo et al. 2021), while three species P. fitae, P. nigricornus Schmarda, 1859, and P. panamensis Woodworth, 1894 are found in the Pacific Ocean.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026CFF9DFD964FD9FAF87EEE.taxon	distribution	Distribution Paita, Peru.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026CFF9DFD964FD9FAF87EEE.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026CFF9DFD964FD9FAF87EEE.taxon	discussion	Remarks Schmarda (1859) made a partial description of the species. It is characterized by an oval-oblong body with a reddish-yellow dorsal region, with numerous spots, conspicuous nuchal pseudotentacles, cerebral eyes arranged in a circle, and tentacular eyes distributed over the pseudotentacles. The reproductive system is located in the central region of the body, featuring a long and conspicuous penis papilla.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026CFF9CFDFF4C7AFB827D67.taxon	distribution	Distribution Punta Marcial, Cabo Pulmo National Park, Baja California Sur; Puerto Peñasco, Sonora; Clarión Island, Revillagigedo Island, Manzanillo, Colima, México; Playa Carbón Beach, in Las Baulas National Marine Park of Guanacaste, Costa Rica.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026CFF9CFDFF4C7AFB827D67.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026CFF9CFDFF4C7AFB827D67.taxon	discussion	Remarks Pericelis ernesti was initially established by Hyman (1953 a) within the suborder Acotylea (family Cryptocelidae) as Marcusia ernesti. Hyman (1953 a) described it as a very peculiar acotyleo that presents characteristics of the suborder Cotylea, such as the distribution of the marginal eyes and the presence of a cement bag in the cement glands, which are emptied by a pair of ducts (see Hyman 1953 a: 287), structures that sensu Hyman (1953 a) are characteristic of the genera Pericelis and Enchiridium Bock, 1913 (suborder Cotylea). Hyman (1955 d: 263) later transferred the species to the genus Pericelis (family Pericelidae, suborder Cotylea) based on the arrangement of the eyes, the coloration pattern (reticulate), the presence of a ventral sucker, and the reexamination of the male and female reproductive system. Faubel (1984 b) subsequently reestablished the species as M. ernesti and transferred it to the family Anonymidae Lang, 1884, but did not mention the criteria for the reestablishment of the species, only mentioning that Hyman (1953 a) overlooked the presence of a sucker. Prudhoe (1985) established Marcusia Hyman, 1953 as a junior synonym of the genus Pericelis, but did not substantiate the criteria for this decision. On the other hand, Cuadrado et al. (2021), through a molecular analysis based on the 28 S marker, validated the separation of Marcusia (represented by Marcusia alba) from the genus Pericelis. This finding contrasts with Tsuyuki et al. (2021) who determined Marcusia as a junior synonym of Pericelis based on a molecular analysis based on the concatenation of the 18 S and 28 S genes. Therefore, the present study suggests a comprehensive review of the biological material of the 12 species of Pericelis.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026DFF93FE0C4E6DFBCC7976.taxon	distribution	Distribution Central coast of Oaxaca: Panteón and Yerbabuena beaches and Cacaluta Bay.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026DFF93FE0C4E6DFBCC7976.taxon	biology_ecology	Habitat Benthic, sublittoral (2 – 10 m). The specimens were collected under rocks, found in groups of two to three individuals per rock and alongside blue sponges, seaweed, polychaetes, and chitons.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38026DFF93FE0C4E6DFBCC7976.taxon	discussion	Remarks Pericelis nazahui lacks a reticular or spotted coloring pattern, but has a brown dorsal surface, with the central region of the body, the margin, and the cerebral region appearing slightly grey, whitish, or beige, and two slightly faint beige lines, each line going from the cerebral region to the pseudotentacles. It has a common gonopores, a scarce internal glandular epithelium, and lacks glandular epithelium in the penis papilla. The female reproductive system features paired uterine vesicles.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380262FF93FE004A7DFDF97C3F.taxon	distribution	Distribution Cacaluta Bay, Oaxaca, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380262FF93FE004A7DFDF97C3F.taxon	biology_ecology	Habitat Benthic, sublittoral (3 – 10 m). Specimens were collected under rocks, found in pairs, alongside seaweed and chitons.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380262FF93FE004A7DFDF97C3F.taxon	discussion	Remarks Pericelis sigmeri is brown, with a color variation to grey or beige. It has black spots and irregular specks of brown and white, with the white specks being notably larger; black spots are mainly concentrated in the central region of the body. Specimens are characterized by a dorsal white spot located in the brain region. The ventral coloration is translucent, with whitish coloration over the pharynx and the reproductive region. It has a common gonopore, the papilla of the penis has internally a glandular epithelium of dense consistency.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380262FF93FD904F26FDDD7E18.taxon	distribution	Distribution Galapagos Archipelago.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380262FF93FD904F26FDDD7E18.taxon	biology_ecology	Habitat Benthic (under rock).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380262FF93FD904F26FDDD7E18.taxon	discussion	Remarks Pericelis sp. 7 was recorded by Newman & Cannon (2003) as an undescribed species of the genus, from the Galapagos Archipelago. T he specimen is characterized by a beige dorsal surface with white and dark mottles with dense black dots.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380262FF92FE434DA4FAC97B84.taxon	distribution	Distribution El Balito, Tenerife, Canary Archipelago, Spain; Carbón Beach, Las Baulas National Park of Guanacaste, Costa Rica.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380262FF92FE434DA4FAC97B84.taxon	biology_ecology	Habitat Benthic, rocky substrates, at depths of 4 – 20 meters or low intertidal, below stones on sand.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380262FF92FE434DA4FAC97B84.taxon	discussion	Remarks Enchiridium magec is a species described in the Atlantic Ocean in the Canary Archipelago by Cuadrado et al. (2017) and subsequently recorded in the Pacific Ocean in Guanacaste Costa Rica by Soutullo et al. (2021). Enchiridium magec is characterized by an elongated body with a smooth dorsal surface. The background color is yellow with cream dots and dark brown spots in the central area, forming a continuous longitudinal midline. The species possesses cerebral eyes and a tubular pharynx. The male reproductive system features a single male gonopore, anterior to the female, with an elongated penis papilla armed with a long tubular stylet, two interpolated prostatic vesicles included in a very characteristic muscular bulb, and a seminal vesicle surrounded by a second muscular bulb. The female reproductive system presents a short, posteriorly oriented vagina, surrounded by cement glands. The present study considers the species’ record on the west coast of Central America as questionable and suggests a review of the material and the mechanisms of interoceanic dispersal of the species.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380263FF92FDAD48CBFE6F7F7C.taxon	distribution	Distribution Laguna Beach, Corona del Mar, Newport Bay, Redondo, Point Arguello, California, United States; Espíritu Santo Island, Baja California Sur, Mexico. The species therefore appears distributed along the southern part of the California coast and in the Gulf of Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380263FF92FDAD48CBFE6F7F7C.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380263FF92FDAD48CBFE6F7F7C.taxon	discussion	Remarks The species is characterized by an elongated body with a dorsal coloration white with cream, with a pattern of black and brown spots, cerebral eyes arranged in two groups, marginal eyes distributed throughout the body, and a tubular pharynx. The male reproductive system oriented towards the posterior region of the body, features an oval seminal vesicle and accessory seminal vesicles, and a penis papilla armed with a sclerosed stipe. The female reproductive system is oriented towards the anterior region of the body, comprising a tubular vagina and a female atrium with glandular pouches (Hyman 1953 a; Brusca 1980, 2005).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380260FF91FD854A5AFCD47BB2.taxon	distribution	Distribution Panama.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380260FF91FD854A5AFCD47BB2.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380260FF91FD854A5AFCD47BB2.taxon	discussion	Remarks Euprosthiostomum adhaerens, established by Bock (1925), is characterized by an elongated body, marginal eyes distributed in the anterior region of the body, and the presence of frontal eyes. The male reproductive system features two separate small prostatic vesicles and a seminal vesicle, and an elongated penis papilla armed with a tubular stylet. However, it is suggested to collect topotypic material and thus make a detailed description of the species.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380260FF91FDBD48FBFAA27F6B.taxon	distribution	Distribution Pacific Northeast Temperate; Santa Catalina Island, California, United States; Puerto Refugio, Ángel de la Guarda Island, Baja California; San Gabriel Bay, Baja California Sur, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380260FF91FDBD48FBFAA27F6B.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380260FF91FDBD48FBFAA27F6B.taxon	discussion	Remarks Prosthiostomum multicelis is characterized by an elongated body with a rounded anterior edge and a blunt posterior region. Its dorsal surface is white or yellow, with a coloration pattern composed of orange speckles. The dorsal axis has a brownish line extending from the brain region to the third of the body, with yellow margins (Brusca 1980). Marginal eyes are distributed in the first third of the body, cerebral eyes are present and a conspicuous tubular pharynx. The male reproductive system is oriented towards the posterior region of the body, comprises oval accessory seminal vesicles, an elongate prostatic vesicle positioned posterior to seminal vesicles, and a penis papilla armed with a prominent stylet. The female reproductive system is oriented towards the anterior region of the body and features a tubular vagina.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380261FF90FF694FB0FD367FFF.taxon	distribution	Distribution Tropical Eastern Pacific. Central coast of Oaxaca: La Tijera and San Agustinillo Beaches.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380261FF90FF694FB0FD367FFF.taxon	biology_ecology	Habitat Fouling. This species is found inside and around empty shells of the barnacle Megabalanus peninsularis (Pilsbry, 1916) which encrust the surf zone of the rocky coast.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380261FF90FF694FB0FD367FFF.taxon	discussion	Remarks The distinction between Prosthiostomum cf. parvicelis and the nominal species is difficult, mainly due to the limited information provided in the original description and redescription by Hyman (1939 b, 1953 b). In the original description and redescription of P. parvicelis, Hyman (1939 b, 1953 b) characterized only the male reproductive system of her specimens focusing on everted structures and the reproductive system in lateral position. Prosthiostomum cf. parvicelis has a light brown color with dark brown to dark green spots distributed around the body, while the dorsal region lacks pigmentation. It has three longitudinal lines, two of which are conglomerate brown to dark green spots distributed from the anterior to posterior region of the body, separated by a thin line without pigmentation. The vagina is oriented towards the anterior region of the body.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380261FF90FDBC4A18FE617C49.taxon	distribution	Distribution Sullivan Bay, Santiago Island; Cartago Bay, Isabela Island, Galapagos Island, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380261FF90FDBC4A18FE617C49.taxon	biology_ecology	Habitat Benthic (at a depth of 14.63 and 18.23 m on a sandy bedrock bottom).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380261FF90FDBC4A18FE617C49.taxon	discussion	Remarks Hyman (1953 b) recorded Prosthiostomum parvicelis as one of the most common polyclad species in the Galapagos Archipelago. The species has an elongated body with sparse marginal eyes distributed in the anterior region of the body, cerebral eyes and tubular pharynx positioned posterior to the cerebral eyes. The male reproductive system features a male gonopore anterior to the seminal vesicle, which as a prominent oval morphology, paired accessory vesicles positioned anterior to the seminal vesicle, spermiducal ducts oriented towards the posterior region of the body, and a penis papilla armed with a stylet. Hyman (1939 a, 1953 b) made a partial description of the female reproductive system in which she only schematized the position of the female gonopore and the distribution of the cement glands. It is recommended to review the type material of the species to provided a detailed redescription of the female reproductive system, together with the collection of new specimens to determine the coloration of these specimens.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380266FF97FE244A18FAF17B6F.taxon	distribution	Distribution Northern Paita, Piura, Peru.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380266FF97FE244A18FAF17B6F.taxon	biology_ecology	Habitat Benthic, in the intertidal zone on rocky shore under a rock.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380266FF97FE244A18FAF17B6F.taxon	discussion	Remarks Prosthiostomum sancum has a dorsal region with brown and black spots forming two dark bands, a cerebral region without pigmentation, and cerebral and marginal eyes present. The male reproductive system features a penis papilla armed with a curved stylet, and paired accessory seminal vesicles.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380266FF96FDD848FAFB837976.taxon	distribution	Distribution La Paz Bay, Baja California Sur, Puerto Peñasco and Miramar Beach, Guaymas, Sonora, Mexico; Carbón and Langosta Beaches, Las Baulas National Park of Guanacaste, Costa Rica.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380266FF96FDD848FAFB837976.taxon	biology_ecology	Habitat Benthic; low intertidal, under stones on sand and in intertidal pools under stones (Soutullo et al. 2021).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380266FF96FDD848FAFB837976.taxon	discussion	Remarks Pseudobiceros bajae is characterized by an oval-elongate body tapered in the posterior region, a black coloration with whitish speckles, pseudotentacles, a sparsely branched pharynx, and a double male reproductive system with an unarmed penis papilla and lacking a cement glandular pouch. Hyman (1953 a) described the species as Pseudoceros bajae. Latre, Faubel (1984 b) established it as the type species of the genus Cryptobiceros Faubel, 1984, determining it as Cryptobiceros bajae, based on the smooth dorsal surface, the double male reproductive system with unarmed penis papilla, the female reproductive system, and the presence of tentacular and cerebral eyes. Subsequently, Newman & Cannon (1994) proposed a new combination for the species and determined it as Pseudobiceros bajae, based on the dorsal coloration pattern, the morphology of the pharynx, the eyes, the pseudotentacles and the anatomy of the reproductive system. However, in Pseudobiceros the determinant character of the genus is the presence of an armed penis papilla, a character absent in Pseudobiceros bajae, therefore, an exhaustive revision of the determinant characters of the species is suggested.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380267FF96FDB74A7DFD677FE3.taxon	distribution	Distribution Pantropical distribution. This species appears to be widely distributed, having been recorded in the Mediterranean, Bermuda, Florida, Puerto Rico, Brazil, Mozambique, Vietnam and the Galapagos archipelago.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380267FF96FDB74A7DFD677FE3.taxon	biology_ecology	Habitat Under rocks and associated with colonial ascidians (botrylloid compound, family Didemnidae Giard, 1872 and of the genus Symplegma Herdman, 1886) and dark purple sponges (Verril 1900; Bahia et al. 2014).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380267FF96FDB74A7DFD677FE3.taxon	discussion	Remarks Pseudobiceros splendidus is part of a group of pseudocerotids (Newman & Cannon 1997) characterized by a black dorsal coloration with an orange submarginal band and black border (review Litvaitis et al. 2019), and small white dots on the dorsal surface (Lang 1884). The species was initially described as Pseudoceros superbus by Lang (1884) and later renamed Pseudobiceros splendidus by Stummer-Traunfels (1933) to avoid confusion with another species of the same name (Marcus 1950). Subsequently, transferred to Pseudobiceros by Faubel (1984 b), due to its double male reproductive system. Litvaitis et al. (2019), based on molecular analysis and coloration pattern, established Pseudobiceros periculosus, Pseudobiceros evelinae, and Pseudobiceros hymanae as junior synonyms of Pseudobiceros splendidus .. Its geographic distribution suggests it may be one of the few truly cosmopolitan polyclads species and evidence of strong intraspecific cohesion.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380264FF95FE7B4A18FBD67B28.taxon	distribution	Distribution Galapagos Archipelago.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380264FF95FE7B4A18FBD67B28.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380264FF95FE7B4A18FBD67B28.taxon	discussion	Remarks Newman & Cannon (2003) only made a photographic record of the dorsal region of Pseudobiceros sp. 6, which exhibits a coloration similar to that of Pseudoceros bicuti Ramos-Sánchez, Bahia & Bastida-Zavala, 2020 (see below). Therefore, the present study suggests the collection of these specimens for a detailed description of the external and internal characters of the species.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380264FF95FE154890FAB27DA6.taxon	distribution	Distribution Panteón Beach, Puerto Ángel, Dos Hermanas Beach and Cacaluta Bay, Huatulco, Oaxaca.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380264FF95FE154890FAB27DA6.taxon	biology_ecology	Habitat Benthic, sublittoral (0.5 – 2 m) (under rocks, in corals of the genus Pocillopora Lamarck, 1816).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380264FF95FE154890FAB27DA6.taxon	discussion	Remarks Pseudoceros bicuti has a black coloration with yellow and white dots, and cerebral and tentacular eyes. The male reproductive system features a prominent seminal vesicle, and the penis papilla presents a penis sheath and is armed with a sclerosed stipe. The female reproductive system lacks Lang’s vesicle.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380264FF94FDAF4EADFE087AE4.taxon	distribution	Distribution Puerto Peñasco, Guaymas, Sonora; Gulf of California, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380264FF94FDAF4EADFE087AE4.taxon	biology_ecology	Habitat Benthic (under rocks in the low intertidal).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380264FF94FDAF4EADFE087AE4.taxon	discussion	Remarks Pseudoceros mexicanus was only partially described by Hyman (1953 a), who only characterized the external morphology of the species, since none of the specimens had a developed reproductive system. Pseudoceros mexicanus has an elongated oval body with a blunt posterior end and a brown or dark purple dorsal region, marginal eyes in the anterior region, tentacular eyes and cerebral eyes distributed in circular form, pseudotentacles; pharynx located in the first third of the body with approximately 15 pharyngeal lobes. Brusca (1980) later recorded the species in the Gulf of California, describing a brown to dark purple or reddish-purple coloration, with a reddish orange margin and a dorsal coloration pattern composed of scattered white speckles. We suggest a thorough revision and comparison of the biological material determined by Hyman (1953 a) and Brusca (1980) for the area. Additionally, we suggest the collection of topotypic material and a redescription of the species to corroborate if the coloration variants and the coloration pattern are part of an intraspecific variation or indicate the presence of two distinct species.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380265FF94FE3A49EBFC9C7CCD.taxon	distribution	Distribution Gulf of Tehuantepec, Oaxaca, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380265FF94FE3A49EBFC9C7CCD.taxon	biology_ecology	Habitat Benthic	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380265FF94FE3A49EBFC9C7CCD.taxon	discussion	Remarks Gamboa-Contreras & Tapia-García (1998), conducted oceanographic collections in the Gulf of Tehuantepec, compiling a list of benthic invertebrates. In this inventory, they recorded the presence of the genus Pseudoceros for that area; however, they did not provide a description or characterization of the species, nor did they includ photographic record of it.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380265FF94FED44E71FAFA7FF5.taxon	distribution	Distribution Central coast of Oaxaca: Estacahuite Beach. This is the first record of the genus for the southern Mexican Pacific.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380265FF94FED44E71FAFA7FF5.taxon	biology_ecology	Habitat Benthic, sublittoral (4 m), under a rock, associated with seaweeds.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380265FF94FED44E71FAFA7FF5.taxon	discussion	Remarks Thysanozoon estacahuitensis has light beige background color with a black pigmentation, which is mostly concentrated along the central axis of the body. The species features sub-triangular and robust dorsal papillae with black pigmentation that diminishes towards their basal regions; the dorsal papillae are scarce, distributed mainly in the central region of the body, becoming less numerous towards the marginal and posterior region of the body. The cerebral eyes are arranged in a semicircular shape.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027AFF8BFD8548D8FEDF7E55.taxon	distribution	Distribution Isthmus of Panama.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027AFF8BFD8548D8FEDF7E55.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027AFF8BFD8548D8FEDF7E55.taxon	discussion	Remarks LeConte (1851), Lang (1884), and Faubel (1984 b) included the species within Polycladida; however, Faubel (1984 b) determined it as a species incertae sedis. The taxon is characterized by a vermiform body, ten eyes on both sides of the anterior region of the body, and small tentacles. Given this sparse description, the present study suggests collecting specimens of this taxon and to confirm its taxonomic identity.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027AFF8BFDDD4A18FD9E7B5B.taxon	distribution	Distribution Gulf of California, Mexico.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027AFF8BFDDD4A18FD9E7B5B.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027AFF8BFDDD4A18FD9E7B5B.taxon	discussion	Remarks Brusca (1980) made a partial description of Thysanozoon sp., determining that the generic character is the presence of dorsal papillae. The species is characterized by an oval body with a rounded posterior body margin. The dorsal surface has a brown to purple dorsal coloration with pale pigmentation and white and purple-brown speckles; the body margin is reticulate with white and light purple stripes. The dorsal papillae have white spots, small dorsal papillae with yellow pigmentation. The species possesses prominent nuchal tentacles, as well as tentacular and cerebral eyes. The pharynx is long and narrow, located in the first third of the body.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027AFF8AFDA74D9CFCAD7AA4.taxon	distribution	Distribution Isthmus of Panama.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027AFF8AFDA74D9CFCAD7AA4.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027AFF8AFDA74D9CFCAD7AA4.taxon	discussion	Remarks LeConte (1851) and Diesing (1862) classified Thyphlolepta extensa as a species incertae sedis within the Turbellaria clade, while Lang (1884) and Faubel (1984 b) placed the taxon within the order Polycladida, classifying it as a species incertae sedis. However, none of these authors made any comments that could be taken into account to amend the status of the species. LeConte (1851) made a partial description of the species, in which he described a flat body, a purple or light brown dorsal coloration, and intestinal tubes. The present study suggests the collection of specimens of the species to make a complete redescription of the species, as well as to define the status of the species.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027BFF8AFE614851FCE57D84.taxon	distribution	Distribution Santa Cruz Island, Galapagos Archipelago, Ecuador.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027BFF8AFE614851FCE57D84.taxon	biology_ecology	Habitat Interstitial (coarse intertidal sediments) or rocks.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027BFF8AFE614851FCE57D84.taxon	discussion	Remarks Faubel (1983) considered C. nexa as a species incertae sedis; arguing that Sopott-Ehlers & Schmidt (1975) only made a partial description of the species, based on external morphological characteristics; they only described an elongated and slender body shape and the distribution of eyes spots. The present study suggests a complete description of the species.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027BFF89FDDE4D2EFEA779CE.taxon	distribution	Distribution Isthmus of Panama.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027BFF89FDDE4D2EFEA779CE.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF38027BFF89FDDE4D2EFEA779CE.taxon	discussion	Remarks LeConte (1851) poorly described the external morphology of Leptoplana discus, focusing solely on its coloration and the number of eyes (without indicating the type of eyes), and did not include any character of the reproductive complex, nor did he make a diagram of the morphology of the species. Faubel (1984 b) designated it as a species incertae sedis, due to the lack of characters that define the species. Therefore, it is recommended that the biological material be reviewed to corroborate the status of the species.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380278FF89FD804934FAB47C49.taxon	distribution	Distribution South of Paita, on the Peruvian coast.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380278FF89FD804934FAB47C49.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380278FF89FD804934FAB47C49.taxon	discussion	Remarks Schmarda (1859) provided a brief description of the species, including characteristics of body shape, coloration and distribution of marginal and cerebral eyes. Regarding the reproductive complex, he only mentioned the presence of separate gonopores. Faubel (1984 b) determines it as a species incertae sedis.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380278FF89FDD14FB0FE477E81.taxon	distribution	Distribution Paita, Peru.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380278FF89FDD14FB0FE477E81.taxon	biology_ecology	Habitat Pelagic (floating free in the Pacific in Paita in Peru).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380278FF89FDD14FB0FE477E81.taxon	discussion	Remarks Schmarda (1859) only described the external morphology of the species, so Faubel (1984 b) assigns it as incertae sedis.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380278FF88FDA64DC8FEA17A41.taxon	distribution	Distribution Paita Peru.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380278FF88FDA64DC8FEA17A41.taxon	biology_ecology	Habitat Benthic.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380278FF88FDA64DC8FEA17A41.taxon	discussion	Remarks Schmarda (1859) made a partial description of the species, as well as a diagram in which he represented the external morphology of the organism. This illustration revealed a cylindrical pharynx, distinctive character of the superfamily Euryleptoidea within the suborder Cotylea. Subsequently, Lang (1884) reassigned the species, determining it as L. taenia. However, he did not establish or determine the characteristics based on the original description; reason for which Faubel (1983) established it as incertae sedis.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380279FF8DFD914830FBAF7FE9.taxon	distribution	Distribution Gulf of Panama.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380279FF8DFD914830FBAF7FE9.taxon	biology_ecology	Habitat Benthic (reef coast).	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
03F2DF380279FF8DFD914830FBAF7FE9.taxon	discussion	Remarks Woodworth (1894) described P. panamensis based on poorly preserved organism, providing only information on its coloration pattern and a diagram of the anterior region of the body (arrangement of cerebral and tentacular eyes). Faubel (1984 b) assigned it as a species incertae sedis. However, based on the anterior morphology of the body represented in the diagram of the species and the coloration pattern, it is considered that this species could belong to the superfamily Pseudocerotoidea Faubel, 1984, for which reason, the present study recommends the collection of topotypic material and a redescription of the species. Historical review After an exhaustive literature search, 51 works detailing and / or documenting the presence of polyclads in the TEP were reviewed. This analysis spanned a period of 173 years (1851 – 2024), revealing intermittent study of polyclads over time (Figs 4 – 5). Pioneers in this field were LeConte (1851) and Schmarda (1859), who described the first seven species in the Isthmus of Panama (3) and Paita, Peru (4), respectively. Woodworth (1894) contributed two new species and a record in the Gulf of California, the central coast of Oaxaca, and the Isthmus of Panama. Plehn (1896) continued this legacy with the description of two new species and a record for Paita, Peru, and one in the Galapagos Archipelago, followed by Bock (1913), who contributed two new species, one in the Galapagos Archipelago and another in San José, Panama. After a lapse of 12 years, Bock (1925) described a species for Panama. Seventeen years later, Hyman (1939 a, 1939 b) marked a milestone by initiating the systematic study of polyclads in the TEP, describing two insular species, one on Clipperton Island (1) and another in the Galapagos Archipelago (1); her work evolved over time, describing 20 new species and making three additional records between the Gulf of California and the Galapagos Archipelago (Hyman 1953 a, 1953 b). These pioneering contributions laid the groundwork for subsequent research, such as that of Cheng & Lewin (1975), who recorded the first pelagic polyclad in La Paz, Baja California Sur, Mexico, and Sopott-Ehlers & Schmidt (1975), who described eight new worm species for the Galapagos Archipelago. Five years later, Brusca (1980) expanded the record with the discovery of two new polyclad species in the Gulf of California. In parallel, Pineda-López (1981) left his mark by documenting an insular species in Nayarit, Mexico. This finding marked the beginning of a series of significant discoveries in the region, as Salgado & López (1981), Marcus & Harry (1982), and Pineda-López & González-Bulnes (1984) contributed to the description and records of three species on the coasts of Nayarit, Baja California, and Jalisco, Mexico, respectively. Fourteen years passed until Gamboa-Contreras & Tapia-García (1998) recorded a hitherto undescribed species of Pseudoceros in the Gulf of Tehuantepec, Mexico. Another five years later, in 2003, Newman & Cannon surprised the scientific community by documenting two previously unknown species, one belonging to the genus Pericelis and another to the genus Pseudobiceros, in the Galapagos Archipelago. The momentum of discoveries continued, as Brusca (2005) expanded his contribution by recording five additional species for the Gulf of California. The discovery of polyclads evolved with Faubel et al. (2007), who enriched knowledge by describing a new species in Jalisco, Mexico. In the last 12 years, a notable advancement in understanding the biodiversity of polyclads has been documented. Ramos-Sánchez et al. (2019, 2020, 2021), Lee et al. (2021), and Soutullo et al. (2021) have played a crucial role in this progress by detailing 13 new species and contributing six additional records on the coasts of Oaxaca, Mexico, as well as in the regions of Costa Rica and the Panama Canal. This body of research has not only significantly expanded our understanding of the presence and variety of polyclads in this region but has also solidified the ongoing importance of research in this field. Numeralia by countries, states, and distribution The polyclad fauna of TEP is composed of 82 species, belonging to two suborders, Acotylea (50 species) and Cotylea (24 species), and eight taxa incertae sedis. These species are distributed across 22 families (17 of Acotylea and five of Cotylea) and 53 genera (41 of Acotylea, 10 of Cotylea, two genera incertae sedis). Of the 82 species, 65 have valid taxonomic status, eight are catalogued as incertae sedis, six are characterized to genus level, two are undescribed species but are classified as close (confer) to the nominal species, and this study includes the description of a new species for the coast of Oaxaca, Mexico. Within Acotylea, the families with the highest species richness are Leptoplanidae (nine species), Planoceridae, and Stylochoplanidae (seven each), and Euplanidae (six), and the most species-rich genera are Leptoplana (five species) and Paraplanocera (four). In the suborder Cotylea, the families with the highest species richness are Prosthiostomidae and Pseudocerotidae (seven species each), while the most species-rich genera are Pericelis and Prosthiostomum (four species each one). Regarding the distribution of these species, 53 of them have their type locality and single record in the TEP. On the other hand, 21 species exhibit a disjunct distribution, covering two localities, while six have a wide distribution in the region, including three or more localities. It is important to note that Enchiridium magec, Planocera pellucida, Paraplanocera oligoglena and Pseudobiceros splendidus show an interoceanic and pantropical distribution, which raises doubts about their records in the TEP. The species of polyclads recorded from TEP are not distributed homogeneously. The Pacific coast of Mexico hosts 45 species (described and recorded). Within Mexico, Baja California Sur (17 species) and Oaxaca (16 species) are the states with the highest number of species recorded, followed by Sonora (14), Baja California (9), Nayarit, Jalisco, and Colima (two species each), and Sinaloa, Michoacán, and Guerrero (one species each). After Mexico, Ecuador is the next country in species richness, with 18 species, 17 of which are from Galapagos Archipelago and one from continental Ecuador (Salinas). Costa Rica and Panama each harbor 10 species, recorded from Guanacaste (northwest of Costa Rica) and the Gulf of Panama. Peru has seven species recorded from Paita, and one species was recorded from Clipperton Island. In Mexico, 31 species have their type localities distributed across 10 of the 11 states that make up the Mexican Pacific coast. Notably, Oaxaca stands out as the type locality of 13 of the 16 species of polyclads present in this state. Likewise, the Galapagos Archipelago is a type locality of 16 of the 18 species distributed in that region. Panama has been designated as a type locality for 8 of the 10 species distributed in the country. Paita, Peru, stands out as the type locality of 6 of the 7 recorded species. Finally, Guanacaste, Costa Rica, has been identified as the type locality for 5 of the 10 species present in that area (Fig. 6). Numeralia by habitats and bathymetry The polyclads that inhabit the TEP are distributed in the pelagic zone and in the benthic zone, where they are found under rocks, between coral rock interspaces, or in association with other invertebrates or seaweed. The largest number of species (65) have been recorded in benthic habitats; of these, 57 are free-living species found under rocks or on dead corals; seven species are interstitial, three have been categorized as symbionts (without specifying the symbiotic relationship), two species as commensals, two ectocomensal, and one as epibiont of barnacles, gastropods or seaweed. Additionally, two species are pelagic and two species are considered part of the fouling. Only six species have been recorded occupying two or more environments (benthic or pelagic) or substrates (rock, other invertebrates, or seaweed) (Table 2). Bathymetric analysis revealed variability in the vertical distribution of these flatworms. In terms of bathymetry, of the 64 species distributed in the benthos, 13 species have a greater vertical distribution range, of which Prosthiostomum parvicelis reaches a depth of 18 meters, while Enchiridium magec 20 meters, Stylochus mistus 25 meters, Cryptocelis insularis 36 meters, and Stylochus (Stylochus) atentaculatus 51 meters. The greatest distribution depths have been recorded for Koinostylochus burchami and Armatoplana panamensis, found at 70 and 73 meters respectively.	en	Ramos-Sánchez, Mariela (2024): The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species. European Journal of Taxonomy 962 (1): 1-67, DOI: 10.5852/ejt.2024.962.2683, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419
