taxonID	type	description	language	source
03DD87FFFFA1FFE9A79DF8EDC8D7F8EF.taxon	description	(Figures 4 A – H, 5 A – E, 6 A – L) http: // zoobank. org / NomenclaturalActs / 8 a 0713 a 4 - 6259 - 4528 - 8 e 76 - 2 d 09 d 7 d 2 e 79 8	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFA1FFE9A79DF8EDC8D7F8EF.taxon	materials_examined	Type locality. Agua Blanca Beach, Oaxaca, México (15 ° 43 ’ 58 ” N, 96 ° 48 ’ 40.21 ” W). Type material. Three specimens. Holotype: UMAR-PLAT 007, Agua Blanca Beach, Oaxaca, southern Mexican Pacific; in tide pools, on Padina sp., together with encrusting bryozoans (Jellyella sp.), 0.5 m, Jan 1, 2014, coll. MRS; specimen in a whole mount. Paratype: UMAR-PLAT 037 A – D, from Agua Blanca, same as holotype; one specimen in histology sections (sagittal sections of reproductive structures in four slides; the remaining portion mounted on Canada balsam in one slide). Other material examined. Oaxaca: One specimen from Agua Blanca, same as type material; used for photography preserved (Fig. 4 A), but destroyed in the mount process.	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFA1FFE9A79DF8EDC8D7F8EF.taxon	description	Description of external features. Color. Translucent in vivo; pharyngeal, intestinal and reproductive region with white granules on translucent background; alcohol-preserved specimens have white opaque to light-brown coloration (Fig. 4 A). The specimen stained with Mayer’s carmalum has a purple to pink color (Fig. 4 B). Body. Oval to circular slightly narrow in the anterior region of the body (Figs 4 A – B, 5 A). The specimens are 3.25 – 5.3 mm long and 2.2 – 3.8 mm wide. Tentacles. Rudimentary pyriform nuchal tentacles (Figs 4 E, 5 A), located at 1.2 – 2.6 mm from the anterior margin of the body; distance between both tentacles is 0.8 – 1.6 mm. Eyes. Marginal eyes absent; with between 25 – 50 tentacular eyes located around the tentacles; with 22 – 55 cerebral eyes at the periphery of the brain and 1.12 mm from the anterior margin of the body (Fig. 4 C). Brain. Bilobed, 0.2 mm long and 2.1 mm wide; located at 1.3 mm from the anterior margin of the body; globuli cell masses triangular shaped, located in the anterior region of the brain (Fig. 4 D). Digestive system. The pharynx is located immediately behind the tentacles (Figs 4 E, H, 5 A, 6 K) located in the central region of the body (Figs 4 E, 5 A), highly branched, 2.4 mm long and 1.7 mm wide; mouth in center. Gonopores. Male and female gonopores located in the last third of the body, posterior to the pharynx. Male gonopore (Figs 4 F, H, 5 B) located at 3.95 mm from the anterior margin of the body, 0.2 mm from the pharynx and 0.12 mm from female gonopore (Figs. 4 G – H, 5 B). Description of internal features. Male reproductive system. Seminal vesicle (Figs 4 H, 5 B, 6 D, L) oval and prominent, 0.7 mm length and 0.32 mm width; covered by a very thin epithelium connected by an ejaculatory duct (Fig. 6 D) to the interpolated prostatic vesicle (Fig. 6 C), which is slightly oval and prominent, poorly differentiated, covered by a smooth glandular epithelium, and has 0.4 mm length and 0.22 mm width. A sclerotized stylet cylindrical with acicular tip (Figs 4 F, 5 B) 0.07 mm length and 0.02 mm width, connected directly to the penis papilla (Fig. 6 E), which is 0.22 mm long and 0.23 mm wide, highly muscular and large. Spermiducal vesicles (Fig. 6 F) oriented towards the posterior region of the body are visible in the sections only; testicles are distributed throughout the body (Fig. 6 I). Female reproductive system. Cement glands (Figs 5 B, 6 H, J) are located posteriorly to male reproductive system. Vagina strongly muscularized (Fig. 6 J), with a paired uterine duct and a uterine sac (Figs 4 H, 5 B, 6 G – H, K), both oriented towards the anterior region of the body. Uterine sac strongly muscularized (Figs 6 G, K), wide proximally (Figs 4 G – H, 5 B) and ovoid distally. Uterine vesicles (Figs 4 H, 5 B, 6 G, I) leave the distal region of the uterine sac towards the posterior region of the body. A pore of the vaginal duct is present posterior to female gonopore (Figs 4 G, 5 B). The Lang’s vesicle is 0.1 mm long and 0.15 mm wide; Lang’s vesicle duct poorly developed, with 0.25 mm length and 0.1 mm width (Fig. 6 J); ovaries (Fig. 6 I) and oviducts (Figs 6 K – L) distributed throughout the body. Habitat. Intertidal, in tide pools. Three specimens of Bisacculosuteri marcelae sp. nov. were found as epibionts on the seaweed Padina sp. and the encrusting bryozoans Jellyella sp. we also found egg masses of B. marcelae sp. nov. deposited on the bryozoans. Other taxa found in the tide pool included seaweed of the genus Ulva, diatoms, polychaetes, brachyuran crabs, amphipods and isopods.	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFA1FFE9A79DF8EDC8D7F8EF.taxon	distribution	Distribution. This species is known only from Agua Blanca Beach, Oaxaca, southern Mexican Pacific (Fig. 12).	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFA1FFE9A79DF8EDC8D7F8EF.taxon	etymology	Etymology. This species is named after Diana Marcela Bolaños-Rodríguez, Colombian researcher, in recognition of her extensive taxonomic, systematic and morphological work on polyclads. Taxonomic remarks. The remarks about this species and comparison with other genera of Leptoplanidae are included in the remarks of genus Bisacculosuteri.	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFADFFECA79DF843CB20FF4B.taxon	type_taxon	Type species. Bisacculosuteri marcelae sp. nov. Ramos-Sánchez, Bahia & Bastida-Zavala, 2019.	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFADFFECA79DF843CB20FF4B.taxon	diagnosis	Diagnosis. Leptoplanidae with oval to circular body; cerebral and tentacular eyes; without marginal eyes; pyriform nuchal tentacles; pharynx folded, distributed in a circular manner in the central region of the body; male reproductive system with prostatic vesicle interpolated poorly differentiated (e. g., no clear separation between the seminal vesicle and the prostatic vesicle); oval and prominent seminal vesicle; spermiducal vesicles present; sclerotized stylet cylindrical with acicular tip; female reproductive system with a uterine duct; a paired uterine sac; ovoid and strongly muscularized uterine vesicles; muscularized vaginal pore, located posteriorly to the female gonopore; a vaginal duct; oval Lang´s vesicle and duct of Lang´s vesicle poorly developed.	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFADFFECA79DF843CB20FF4B.taxon	etymology	Etymology. The generic name was applied taking into account the possession of a double uterine sac in the female reproductive system. Taxonomic remarks. Leptoplanidae is a family composed by eight genera: Leptoplana Ehrenberg, 1831; Hoploplana Laidlaw, 1902; Haploplana Bock, 1913; Notoplanides Palombi, 1928; Indiplana Strummer-Traunfels, 1933; Itannia Marcus, 1947; Longiprostatum Hyman, 1953; Parviplana Hyman, 1953; Leptoplanella Faubel, 1983 and Bivesiculoplana Pineda-López & González-Bulnes, 1984. A new species of Leptoplanidae discovered in Oaxaca was not possible to determined in any of these genera. Bisacculosuteri gen. nov. belongs to Leptoplanidae by virtue of lacking marginal eyes, ruffled pharynx central of the body; male reproductive system directed backwards behind the pharyngeal cavity; gonopores separate; prostatic vesicle poorly differential, covered by a smooth glandular epithelium, without distinct muscle wall, lacking accessory prostatic vesicles but with a seminal vesicle. The genus Itannia is most similar to Bisacculosuteri gen. nov., with which it shares some external features such as a similar body shape, nuchal tentacles, cerebral and tentacular eyes, and pharynx morphology; however, it differs from Itannia by the morphology of the reproductive system and because Itannia has a paired ventral sucker in both sides of the female gonopore (Marcus 1952; Du Bois-Reymond Marcus 1957; Faubel 1983), a character lacking in Bisacculosuteri gen. nov. Bisacculosuteri gen. nov. differs from Leptoplana because the former has nuchal tentacles and lacks a sucker, or genital pit, between male and female gonopores; while Leptoplana does not have tentacles and has a sucker between male and female gonopores (Ehrenberg 1831; Faubel 1983). Bisacculosuteri gen. nov. differs from Hoploplana because the former has a conspicuous seminal vesicle, a character absent in Hoploplana (Laidlaw 1908; Faubel 1983). Bisacculosuteri gen. nov. differs from Indiplana because the latter genus lacks nuchal tentacles and has tripartite vesicle that consists of a prostatic-like ejaculatory duct and spermiducal bulbs (Strummer-Traunfels 1933; Faubel 1983), while Bisacculosuteri gen. nov. has nuchal tentacles, and the vesicle is interpolated and poorly differentiated. Bisacculosuteri gen. nov. differs from Longiprostatum mainly in the arrangement of the eyes: Longiprostatum has cerebral-frontal eyes groups and marginal eyes (Hyman 1953 a; Faubel 1983), while Bisacculosuteri gen. nov. has cerebral and tentacular eyespots, and has no marginal eyes. Bisacculosuteri gen. nov. differs from Parviplana since this genus lacks nuchal tentacles and stylet (Hyman 1953 a; Faubel 1983), both characters present in Bisacculosuteri gen. nov. Leptoplanella has a cuneate body, prominent nuchal tentacles and lacks Lang´s vesicle (Faubel 1983), while Bisacculosuteri gen. nov. has a circular body, shorter nuchal tentacles and a Lang’s vesicle. Bisacculosuteri gen. nov. presents a simple Lang´s vesicle and a prominent seminal vesicle, while Bivesiculoplana lamothei presents a paired Lang’s vesicle and a rudimentary seminal vesicle. Both genera also differ in the type of habitat: B. lamothei is an ectocommensal species of limpets (Pineda-López & González-Bulnes 1984), while Bisacculosuteri gen. nov. is associated with seaweed. The genera Haploplana and Notoplanides are included within the family; however, their type species were transferred to the genus Euplanoida Faubel, 1983, of the Superfamily Ilyplanoidea, and to the genus Stylochoplana (Stimpson, 1857) of the Superfamily Leptoplanoidea, respectively (Faubel 1983; Prudhoe 1989); thus, both genera should be redefined. Bisacculosuteri gen. nov. differs from Haploplana because the later genus lacks an armed penis papilla and nuchal tentacles (Bock 1913; Faubel 1983), while Bisacculosuteri gen. nov. has both characters. On the other hand, the genus Notoplanides has an unarmed penis papilla, an elongated body and prominent nuchal tentacles (Palombi 1928; Faubel 1983), while Bisacculosuteri gen. nov. has an armed penis papilla, an oval / circular body and the nuchal tentacles are rudimentary. Considering all these differences from the other genera of the family Leptoplanidae, Bisacculosuteri gen. nov. is established.	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFA9FFE6A79DFCF6C9F1FC73.taxon	diagnosis	Diagnosis. Euplanidae of oval, obovate, or cuneiform body; without nuchal tentacles; with tentacular and cerebral eyes that join together as cerebral-tentacular eyes; without marginal eyes. Gonopores separate; male reproductive system directed backward; with seminal vesicle, spermiducal vesicle, spermiducal ducts and unarmed penis papilla; female reproductive system with Lang’s vesicle (modified of Faubel 1983).	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFA9FFE2A79DFB96CB33F896.taxon	description	(Figures 2 A – K, 3 A – E)	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFA9FFE2A79DFB96CB33F896.taxon	type_taxon	Type locality of nominal species. Valparaiso, Chile (Plehn 1896: 153 – 155, pl. 10, Figs 7, 9, pl. 13, Fig. 10; on bottom of a boat).	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFA9FFE2A79DFB96CB33F896.taxon	materials_examined	Material examined. Fourteen specimens. Seven specimens as whole mounts: UMAR-PLAT 001, 1 spec. (Panteón Beach, under rocks, 3 m, Oct 28, 2012, coll. MRS); UMAR-PLAT 002, 002 A, 2 spec. (Puerto Ángel Beach, under rocks, 3 m, Oct 28, 2012, coll. AR); UMAR-PLAT 003, 1 spec. juvenile (Agua Blanca Beach, under rocks in tidal pools, 0.5 m, Nov, 2013, col. MRS); UMAR-PLAT 004, 1 spec. (Camarón Beach, under rocks, 3 m, Dec 6, 2014, coll. ECL); UMAR-PLAT 005, 1 spec. (Estacahuite Beach, under rocks, 2 m, Oct 6, 2013, coll. MRS); UMAR-PLAT 006, 1 spec. (Yerbabuena Beach, under rocks, 12 m, Oct 9, 2013, coll. MRS). Four specimens in histology sections: UMAR-PLAT 001 A – F, 1 spec. (sagittal sections of reproductive structures in six slides; Panteón Beach, under rocks, 3 m, Oct 28, 2012, coll. AR); UMAR-PLAT 004 A – F, 2 spec. (sagittal sections of reproductive structures in six slides); UMAR-PLAT 004 G – J, 1 spec. (frontal sections of reproductive structures in four slides; Camarón Beach, under rocks, 0.5 m, Feb 25, 2017, coll. MRS). Three specimens preserved in 70 % ethanol: UMAR- PLAT 002 B (Puerto Ángel Beach, under rocks, 3 m, Oct 28, 2012, coll. AR & MRS).	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFA9FFE2A79DFB96CB33F896.taxon	description	Description of external features Color. In vivo the specimens are translucent, variable color from grayish or beige, to pink, light brown, orange (Figs 2 A – E); pharynx and intestinal branches are visible and according from the gut content could be varied to white, brown, pink or dark green (Fig. 2 A). In mature specimens, testes and ovaries are also visible scattered in the parenchyma, both light brown. In ethanol, specimens become white or beige, opaque in appearance. Body. Body shape elongate or cuneiform (Figs 2 A – E), with 6 – 30 mm (n = 14, µ = 15.16 mm, SD = 6.28) long, and 2.2 – 10 mm (n = 13, µ = 5.86 mm, SD = 2.2) wide; the anterior margin is rounded and the posterior margin is slightly pointed (Figs 2 C – E). Tentacles. Without nuchal tentacles. Eyes. Without marginal eyes; the cerebral eyes are located at 1.3 – 7.3 mm (n = 5, µ = 3.82 mm, SD = 4.88) from the anterior margin of the body, these are distributed in the periphery of the brain and are arranged in two lines, which surpass the anterior and posterior region of the brain; tentacular eyes clustered in a circle, scarce (Fig. 2 F) the tentacular eyes become confused with the cerebral eyes as they join together, these are named cerebral-tentacular eyes. Brain. Bilobed, 0.35 mm (n = 5) of long and wide, presents globuli cell masses of circular – oval shape, that are lodged in the anterior region of the brain (Fig. 2 G). Digestive system. Pharynx (Fig. 2 H) elongated and highly branched, located at the central region of the body, at 1.3 – 7.3 mm (n = 5, µ = 3.96 mm, SD = 2.22) of distance from the anterior margin; pharynx measures 3 – 4.6 mm (n = 5, µ = 3.8 mm, SD = 0.66) long, and 0.6 – 1.6 mm (n = 5, µ = 0.92 mm, SD = 0.41) wide; the mouth in the last third of the pharynx, at a distance from the anterior margin of 6 mm, with 12 – 14 (n = 5, µ = 13, SD = 0.70) pharyngeal lobes. Gonopores. Separated, located in the last third of the body. Male gonopore (Figs 3 A – C, E) at 6 – 12.7 mm (n = 5, µ = 5.14 mm, SD = 5.34) from the anterior margin and 0.8 – 3.6 mm (n = 5, µ = 1.15 mm, SD = 1.47) from the pharynx. The female gonopore (Figs 3 A – B) is positioned posterior to the male gonopore, at 0.05 mm of distance. Description of internal features Male reproductive system. Without prostatic vesicle; tripartite oval seminal vesicle with 0.25 – 0.5 mm (n = 5, µ = 0.22 mm, SD = 0.21) of diameter (Figs 2 K, 3 A, D); thickened spermiducal ducts that connect ventrally with the seminal vesicle (Figs 2 K, 3 A); all of these positioned anterior to the male gonopore; the spermiducal ducts internally present spermiducal oval-shaped vesicles (Figs 2 K, 3 A – D); these ducts and vesicles ascend to the anterior region of the pharynx, then bifurcate in the second third of the pharynx and reach the second third of the Lang’s vesicle. The seminal vesicle connects to the penis papilla through an ejaculatory duct (Fig. 3 D); penis papilla conical, slightly pointed and unarmed (Fig. 3 C), which is 0.1 mm long and 0.05 mm wide; male atrium (Fig. 3 C) 1 mm long and 0.25 mm wide, and its walls are delimited by a glandular epithelium. Female reproductive system. With cement glands (Fig. 3 A) around the female gonopore; a short female atrium directly connected to the vagina (Fig. 3 B), oriented towards the anterior region of the body, slightly scalloped and delimited by a ciliary epithelium; the vagina is connected by means of a Lang’s duct (Figs 3 B, E) with the very elongated Lang’s vesicle (Figs 2 I, 3 A – B, E), reaching 1 – 2.2 mm (n = 7, µ = 1.17 mm, SD = 0.76) of length and 0.2 – 0.85 mm (n = 7, µ = 0.26 mm, SD = 0.33) in width; it is located posteriorly to the female gonopore and oviduct; the latter is located around the pharynx. Habitat. Littoral to sublittoral (12 m); under rocks, associated with green seaweed, bryozoans and chitons. Can be found in groups of 2 – 4 specimens per rock (MRS personal observation).	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFA9FFE2A79DFB96CB33F896.taxon	distribution	Distribution. Euplanoida cf. pacificola was found at Camarón, Puerto Ángel, Estacahuite and Yerbabuena beaches, Oaxaca. Is the first record of the genus for the southern Mexican Pacific (Fig. 12). Taxonomic remarks. This family includes nine genera: Euplana Girard, 1893; Diplopharyngeata Plehn, 1896; Semonia Plehn, 1896; Aprostatum Bock, 1913; Taenioplana Hyman, 1944; Euplanina Sopott-Ehlers & Schmidt, 1975; Euplanoida Faubel, 1983, Paraprostatum Faubel & Sluys, 2007 and Namyhplana Brusa & Damborenea, 2013. The specimens of this study were determined as belonging to the genus Euplanoida by the presence of a seminal vesicle, an unarmed penis papilla, a Lang’s vesicle and the absence of nuchal tentacles, marginal and frontal eyes (Faubel 1983). Euplanoida has six species: the type species, E. pacificola (Plehn, 1896), described from Valparaiso, Chile, has been recorded on the Peruvian coasts and in the Gulf of California (Hyman, 1953 a); E. elioti (Laidlaw, 1903 a), described from Kenya and / or Zanzibar, Eastern Africa; E. malayana (Laidlaw, 1903 b), described from Strait of Malacca, Indonesia; E. panangensis (Laidlaw, 1903 b), described from Palau Island, Malaysia; E. concolor (Meixner, 1907), described from Musha Island, Djibouti and E. tropicalis (Hyman, 1954), described from Kapoho, Hawaii. The specimens of the present study were determined as E. cf. pacificola, because of the presence of a prominent tripartite seminal vesicle of 0.25 – 0.5 mm (n = 5, µ = 0.22 mm, SD = 0.21) of diameter; symmetrical duct of spermiducal vesicles and spermiducals vesicles, both positioned ventrally to the oviduct and anteriorly to the male gonopores; a short penis papilla (L = 0.1 mm, W = 0.05 mm), unarmed; very elongated Lang’s vesicle (L = 1.16 mm); cerebral and tentacular eyes form join as cerebral-tentacular eyes; absence of tentacles, marginal and frontal eyes (Figs 2 A – K, 3 A – E). The separation between Euplanoida cf. pacificola and the nominal species is difficult, mainly by the ambiguous information of the original description, the possible artifices in the process of fixation and / or stages of life of the specimens, and the color variations between the specimens reviewed by Plehn (1896), Hyman (1953 a) and the present study (see Table I). Type specimens of Euplanoida pacificola were collected on the keel of the boat, “ am Kiel des Schiffes haftend ”, from Valparaiso, Chile, and also recorded in the Peruvian coasts (Plehn 1896). The specimens from Perú were determined as a variation of E. pacificola, according to Plehn (1896: 153). Later, Hyman (1953 a) recorded this species from Guaymas, Sonora, and Punta San Marcial, Baja California Sur, determining it as a Mexican variation of the nominal species. Notwithstanding morphological differences observed in the hermaphroditic reproductive system and the geographical distance of the topotypical locality, Hyman (1953 a) considered that it did not justify the separation of the taxon into more species, since the Chilean taxon was collected from the bottom of a boat in Valparaíso, and hence not necessarily native to the locality. The conspicuous character in Euplanoida cf. pacificola is the presence of a tripartite seminal vesicle and the symmetrical distribution of the spermiducal ducts and vesicles and the absence of a bursa copulatrix (this only present in the Chilean specimen); both characters are mentioned as present in the Peruvian and Mexican variations of E. pacificola but the arrangement of them is unknown (Plehn 1896, Hyman 1953 a). The illustration of the complete Chilean specimen (Plehn 1896: pl. 10, Fig. 7) of E. pacificola outlines the presence of a bursa copulatrix; however, their description does not mention said structure. Likewise, Hyman (1953 a) does not say anything about this character, nor her opinion about the discrepancy in their ecological differences between temperate-cold waters from Chile versus tropical waters from Gulf of California. Therefore, the exhaustive revision of the holotypes recommended, as well as the variations determined by Plehn (1896) and Hyman (1953 a). In this study five color variations of Euplanoida cf. pacificola were observed (Fig. 2 A – E); they could be mainly attributed to the bathymetric distribution of the species (0.5 – 12 m), since no visible differences were found in the morphology.	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFB8FFF7A79DFCDAC89AFC64.taxon	diagnosis	Diagnosis. Planoceridae with oval or circular body; robust and conspicuous nuchal tentacles; without marginal eyes, with cerebral and tentacular eyes; the pharynx is located in the central region of the body; gonopores separate; male reproductive system lacks a seminal vesicle; with a prostatic vesicle; spermiducal vesicle; cirrus sac with spines and conspicuous teeth and female reproductive system with bursa copulatrix; vagina with scalloped epithelium and Lang´s vesicle (modified from Faubel 1983).	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFB8FFF2A79DFBEAC816FCC3.taxon	description	(Figures 10 A – H, 11 A – H) http: // zoobank. org / NomenclaturalActs / b 5240 c 22 - 8260 - 44 c 4 - ac 86 - f 304718 bec 2 b	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFB8FFF2A79DFBEAC816FCC3.taxon	materials_examined	Type locality. Agua Blanca Beach, Puerto Escondido, Oaxaca, México (15 ° 43 ’ 58 ” N, 96 ° 48 ’ 40.21 ” W). Type material. Eleven specimens. Holotype: UMAR-PLAT 012, as whole mount (Agua Blanca Beach, Puerto Escondido, Oaxaca, southern Mexican Pacific, under rocks in tidal pools, 0.5 m, Mar 24, 2010, coll. MRS). Paratypes: Six specimens as whole mounts; UMAR-PLAT 038 (Agua Blanca Beach, same as holotype); UMAR-PLAT 013, 013 A (Panteón Beach, under rocks, 1 m, Feb 26, 2014, coll. ECL); UMAR-PLAT 014 (Camarón Beach, under rocks, 1.5 m, Dec 6, 2014, coll. ECL); UMAR-PLAT 015 (Cacaluta Bay, under rocks, 12 m, May 7, 2013, coll. EEA); UMAR-PLAT 038 B – F, specimen in histological sections (sagittal sections of reproductive structures in four slides, the remaining portion of the specimen preserved in glycerin; Agua Blanca Beach, same as holotype). UMAR- PLAT 016, three specimens preserved in 70 % ethanol: incomplete specimens (the region of the reproductive system was sectioned to subject it to the histological process, but it was not successful; Agua Blanca Beach, same as holotype); UMAR-PLAT 017, one specimen preserved in 70 % ethanol (Panteón Beach, same as UMAR-PLAT 013).	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFB8FFF2A79DFBEAC816FCC3.taxon	description	Description of external features. Color. The body in vivo is translucent, dorsally presenting a faintly pigmentation of light brown color, margins yellow; brown intestinal ramifications; slightly grayish and brown irregular specks distributed throughout the body and black dots distributed in the pharyngeal and reproductive region of the specimen (Figs 10 A, F – G). Ventral region translucent with pharyngeal and reproductive whitish region. One specimen preserved in alcohol has brown coloration (Fig. 10 B). Specimen stained with Mayer’s carmalum has a purple to pink color (Fig. 10 C). Form. Oval to round body; 13 – 40 mm (n = 10, µ = 25 mm, SD = 12.2) long and 10 – 36 mm (n = 10, µ = 21, SD = 11.5) wide (Figs 10 A – C). Tentacles. Robust and conspicuous nuchal tentacles; located at 1.7 – 11.05 mm (n = 10, µ = 7 mm, SD = 3.8) from the anterior margin of the body; bicolored, the apical region is cream and the basal region is dark brown or black (Figs 10 D, F), the right tentacle is 0.68 – 1.19 mm (n = 10, µ = 1 mm, SD = 0.2) and the left tentacle is 0.68 – 1.36 mm (n = 10, µ = 1 mm, SD = 0.3), distance between tentacles is 0.85 – 1.7 mm (n = 10, µ = 1 mm, SD = 0.4). Eyes. Without marginal eyes; with 68 – 106 (n = 10, µ = 85, SD = 8.5) tentacular eyes, distributed around each nuchal tentacle; with 7 – 115 (n = 10, µ = 94, SD = 11) cerebral eyes arranged in two clusters, one densely concentrated and located anteriorly to the brain, the second group is scattered and located posteriorly to the brain (Fig. 10 D). Brain. Bilobed, 600 μm long and 620 μm wide; globuli cell masses located in the anterior region of the brain (Fig. 10 E). Digestive system. The pharynx located in the central region of the body, at 4.6 – 11.05 mm (n = 10, µ = 9 mm, SD = 4.4) from the anterior margin, measuring 3.7 – 7.65 (n = 10, µ = 5 mm, SD = 2.3) of length and 0.2 – 7.65 mm (n = 10, µ = 2 mm, SD = 0.8) in width; pharynx sparsely branched with 4 – 9 (n = 10, µ = 6, SD = 1.6) lateral pharyngeal lobes. Mouth located in the last third of the pharynx (Fig. 10 G). Gonopores. Gonopores separated, located in the median line of the body, posterior to the pharynx. Male gonopore located at 10 – 14 mm (n = 10, µ = 12 mm, SD = 2.8) from the anterior margin and 1.5 mm from the pharynx. Female gonopore located at 12 – 14 mm (n = 10, µ = 14 mm, SD = 3) from the anterior margin, 2 mm from the pharynx and 0.5 mm from the male gonopore (Fig. 10 H). Description of internal features Male reproductive system: Without seminal vesicle; with an oval accessory prostatic vesicle, separated from the prostatic vesicle by a thin epithelium and delimited with some eosinophilous granules; conspicuous oval prostatic vesicle (Figs 10 H, 11 A, D), 60 – 75 μm (n = 4, µ = 68 μm, SD = 7.5) long and 62 – 90 μm (n = 10, µ = 73 μm, SD = 10) wide, covered with highly folded epithelium; prostatic vesicle located anterior to the male gonopore and posterior to the pharynx (Fig. 10 H), connecting to the cirrus sac (Figs 10 H, 11 A, E – F) through a spermiducal duct, which is attached to the prostatic duct (Fig. 11 D). Cirrus sac slightly oval (Figs 10 H), with 70 – 170 μm (n = 10, µ = 124 μm, SD = 10) long and 63 – 130 μm (n = 10, µ = 87 μm, SD = 16.6) wide; the walls of the cirrus sac has surrounding intramuscular spaces apparently empty (Fig. 11 D); the cirrus sac is armed with spines (Figs 11 E – G) positioned transversely along the cirrus; dorsal and ventral spines triangular and with similar size (Figs 11 G); and with a pair of conspicuous and asymmetrical teeth (Fig. 11 B) (ventral view); in sagittal view 200 μm long and wide at the basal region 190 μm and 200 μm at the apical region (Figs 11 A – C); the posterior region of the cirrus sac narrow, connecting it to male atrium (Fig. 11 A), the male atrium has a glandular sac (Fig. 11 E). Spermiducal vesicles (Fig. 10 H) extend transversely to the prostatic vesicle; short and oval spermiducal bulbs present (Fig. 11 A), each of them attached to the spermiducal duct by means of a sperm duct located posteriorly to the prostatic vesicle (Fig. 11 D). Female reproductive system: Located in the postero-lateral region of the male reproductive system; with a pyriform bursa copulatrix (Figs 10 H, 11 A), i. e., a hollow oval sac, 160 – 360 μm (n = 10, µ = 200 μm, SD = 58) long and 62 – 180 μm (n = 10, µ = 111 μm, SD = 43) wide, covered by a very thin wall of fibrous tissue, which gives it the appearance of being cuticularized (Fig. 11 A). The bursa copulatrix is positioned on the left side of the cirrus sac and anterior to the female gonopore (Fig. 10 H). Vagina (Fig. 11 H) directed towards the anterior region of the body, with scalloped epithelium, irregular walls and a short cement pouch (Fig. 11 H). Lang’s vesicle elongated and located posteriorly to female gonopore (Figs 10 H, 11 A); female gonopore oriented towards the posterior region of the body, connecting dorsally with the duct of Lang’s vesicle (Fig. 10 H). Cement glands very densely (Figs 11 A, H) arranged around the vagina (Fig. 11 H). Habitat: Littoral to sublittoral (12 m); under rocks, associated with encrusting bryozoans, green seaweed and chitons. Paraplanocera oligoglenoides sp. nov. can be found in pairs or alone.	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFB8FFF2A79DFBEAC816FCC3.taxon	distribution	Distribution. Southern Mexican Pacific. Paraplanocera oligoglenoides sp. nov. was found at Agua Blanca, Camarón, Panteón and Puerto Angel beaches and in Cacaluta Bay, Oaxaca. This is the first record of the genus from the southern Mexican Pacific (Fig. 12).	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
03DD87FFFFB8FFF2A79DFBEAC816FCC3.taxon	etymology	Etymology: The specific epithet refers to the similarity of the new species with Paraplanocera oligoglena (Schmarda, 1859). Taxonomic remarks. The status of the species of the genus Paraplanocera has generated much controversy (Hyman 1959) and has been discussed by Kato (1936), Prudhoe (1945) and Hyman (1953 a). Kato (1936 in Prudhoe 1945) separated the species of this genus into two groups, characterized by the presence or absence of a pair of “ glandular pockets ” opening into the male antrum; posteriorly, Prudhoe (1945: 197 – 198, Figs 1 – 2) reduced the number of species of the genus from eight to three valid species: Paraplanocera oligoglena, P. aurora Laidlaw, 1903 and P. marginata Meyer, 1922, and proposed a division of the genus in two groups based on the internal morphology of the male reproductive system: Group 1: Species with the cirrus-cavity lined with numerous spines, comparatively large near the male antrum, while the spermiducal ducts (or “ the canals from the seminal vesicles ”) open into the ventral wall of the prostatic vesicle (or “ prostatic organ ”). Group 2: Species with the cirrus-cavity lined with numerous small spines and a pair of very large projections covered with a layer of brownish hyaline substance, while the spermiducal ducts open into the prostatic vesicle only just before it enters the cirrus. However, Hyman (1955) and Faubel (1983) considered that the criteria established by Prudhoe (1945) lacked a detailed review of the characters, due to the lack in the availability of the descriptions for each species of Paraplanocera; therefore, Faubel (1983) considered ten Paraplanocera species to be valid in his classification. Two species were recorded from Tropical Eastern Pacific: Paraplanocera oligoglena, originally described by Schmarda (1859) from Sri Lanka, Indian Ocean, and later recorded from Gulf of California (Hyman 1953 a; Brusca 1980; Lamothe-Argumedo et al. 1997); and P. oceanica described by Hyman (1953 b), from Isabela Island, Galapagos. Other similar species, P. fritillata, was described by Hyman (1959) from Caroline Islands, Micronesian Archipelago. Paraplanocera oligoglena was recorded from the Indo-Western Pacific (Schmarda 1859, Stummer-Traunfels 1933, Hyman 1954, 1955, Prudhoe 1978, Ken-Ichi et al. 1991). In the Mexican Pacific, P. oligoglena was recorded from Coronado Island, Baja California; Punta San Marcial reef, Baja California Sur and Miramar Beach, Sonora (Hyman 1953 a, Brusca 1980, Lamothe-Argumedo et al. 1997). Prudhoe (1985) considered P. oligoglena as a circumtropical species. Paraplanocera oligoglenoides sp. nov. differs from P. oligoglena in the dorsal coloration pattern, number of cerebral eyes, the intramuscular content of the surrounding spaces of the cirrus sac cavity, the accessory prostatic vesicle epithelium, the orientation, position and morphology of the vagina and of the bursa copulatrix (Table III). Paraplanocera oligoglenoides sp. nov. differs from P. oceanica (Hyman 1953 b: 191 – 193; figs 8 – 11) in the composition of the male reproductive system, and because the latter species has a cirrus sac with an elongated penis papilla that is armed with small spines in the terminal region (Hyman 1953 b), while in P. oligoglenoides sp. nov. the cirrus sac lacks penis papilla; the entire cirrus sac has spines and conspicuous paired teeth. Paraplanocera oligoglenoides sp. nov. differs from P. fritillata (Hyman 1959: 558 – 562; Figs 5 b – d, 6 a) in the distribution of the spines in the cirrus sac (P. fritillata lacks spines in the anterior region of the conspicuous tooth); the Lang’s vesicle positioned lateral to the bursa copulatrix (sagittal view); pharynx folded-circular and the mouth is positioned in the central region of the pharynx; while in P. oligoglenoides sp. nov. the spines of the cirrus sac are distributed anterior and posterior to the conspicuous tooth; the Lang’s vesicle positioned dorsally to the bursa copulatrix (sagittal view), pharynx folded-elongate and the mouth is positioned in the last third of the pharynx. Although Prudhoe (1945) did not consider dorsal coloration pattern, being variable depending on the habitat and ecological parameters, as a character that permits a specific determination; however, Hyman (1959) and our study suggest taking this character also into account, because well-recorded coloration patterns in vivo allow the separation between P. oligoglena, P. fritillata and P. oligoglenoides sp. nov. (Table III). Likewise, future studies should evaluate the number of teeth in the cirrus sac, accessory prostatic vesicles, and morphology and position of the bursa copulatrix and Lang’s vesicle. Both, P. oligoglena (see Hyman 1953 a: 357, Fig. 124; 1955: 77 – 78, Fig. 4 c) and P. oligoglenoides sp. nov., have variation in these characters, which previously had been considered as a intraspecific variation characters (Prudhoe 1945; Hyman 1953 a). In the same way, the historical records of P. oligoglena in the Gulf of California (Hyman 1953 a; Brusca 1980), should be revised for confirm if the determination was correct.	en	Ramos-Sánchez, Mariela, Bahia, Juliana, Bastida-Zavala, J. Rolando (2019): New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific. Zootaxa 4700 (1): 30-58, DOI: 10.11646/zootaxa.4700.1.2
