taxonID	type	description	language	source
038E6046FFF9FF8437E3F8B3FA5AAE46.taxon	materials_examined	Material examined. Holotype: male (CL 6.8, TL 20.1), MNRJ 17905, Brazil, Atol das Rocas, Ilha do Cemitério, coll. F. B. Pitombo and R. Barroso, 24 Dec 2000. Paratypes: 1 female (CL 7.0, TL 22.9), MNRJ 20048, same collection data as holotype; 2 females (CL 6.2, TL 17.5 and CL 6.2, TL 16.9, latter dissected), MNRJ 17926, Brazil, Atol das Rocas, in front of Ilha do Cemitério, near algal crest, with suction pump, coll. F. B Pitombo and R. Barroso, 31 Dec 2000. Additional material examined. 1 male (CL 6.7, TL 19.7), USNM 1100667, Panama, Caribbean coast, Bocas del Toro, Isla Carenero, near Bucaneer resort, 15 m from shore, depth 0.5 m, fine sand flat with seagrass, with suction pump, from burrow of Ochetostoma cf. edax (host collected and preserved), coll. A. Anker, 17 Oct 2005 [fcn 05 - 019].	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF9FF8437E3F8B3FA5AAE46.taxon	description	Description. Carapace smooth, not setose, laterally not compressed. Rostrum short, triangular to subtriangular, distally subacute (Fig. 1 a, h), situated somewhat below dorsal-most portion of orbital hoods (Fig. 1 b); mediorostral carina feebly marked, blunt and short, not reaching beyond eye level, posteriorly flattening (Fig. 1 a); orbitorostral grooves very shallow; orbitorostral process not conspicuous. Orbital hoods moderately inflated, rounded, unarmed (Fig. 1 a). Pterygostomial angle rounded, not protruding (Fig. 1 b). Branchiostegial margin furnished with scarce setae. Cardiac notch relatively small. Eyes completely concealed in dorsal, lateral and partly frontal view. Ocellar beak well-developed, protruding vertically towards rostrum, visible in lateral view (Fig. 1 b). Epistomial sclerite without acute projecting tooth. Antennular peduncles moderately stout, second segment slightly longer than dorsally visible portion of first segment, about 1.5 times as long as wide (Fig. 1 a); stylocerite short, distally blunt to subacute (Fig. 1 a, b), not reaching distal margin of first segment; mesioventral carina of first segment with tooth as illustrated (Fig. 1 c); lateral flagellum without independent secondary ramus, groups of aesthetasc tufts present starting from fifth segment (Fig. 1 a, b). Antenna with basicerite lacking ventrolateral tooth (Fig. 1 a, b); carpocerite robust, reaching distinctly beyond distal margin of antennular peduncle and scaphocerite; scaphocerite exceeding distal margin of antennular peduncle, with deep cleft between distolateral tooth and blade (Fig. 1 a, d), lateral margin slightly concave (Fig. 1 d), distolateral tooth reaching beyond anterior margin of blade (Fig. 1 a, d). Mouthparts (mandible, maxillule, maxilla, first and second maxillipeds) typical for Alpheus. Third maxilliped relatively stout (Fig. 1 e); coxa with lateral plate ear-shaped, distally acute, furnished with long setae; antepenultimate segment flattened, with ventral margin somewhat rugose, dorsal margin with short, blunt distal projection; ultimate segment very setose; exopod not reaching penultimate segment; arthrobranch welldeveloped (Fig. 1 e). Major cheliped (Figs. 2 a – c; 5 a, b) with short, robust ischium; merus stout, about twice as long as wide, dorsal margin distally blunt, not projecting, ventromesial margin finely toothed, distally with subacute tooth (Fig. 2 a, b); carpus cup-shaped, without distinct distal lobes; chela ovate, laterally compressed, subrectangular in cross-section; dorsal margin of palm with deep transverse notch subdistally (Fig. 2 a, b), forming a broadly U-shaped groove in dorsal view; mesial face of palm smooth except for small depression near dorsal notch (Fig. 2 a); lateral face with narrow, longitudinal dorsal depression extending from dorsal notch to linea impressa, and broad, very shallow ventral depression extending from base of pollex to about mid-length of palm (Fig. 2 b); fingers about 3 / 5 length of palm; dactylus with short, distally truncate plunger, latter with stamen-shaped sensillae (Figs. 2 b, 5 c); adhesive discs rather small (Fig. 2 b). Female minor cheliped (Fig. 2 d, e) with robust merus, about 2.5 times as long as wide; dorsal margin distally unarmed; ventromesial margin finely toothed, distally with small subacute tooth (Fig. 2 d, e); carpus short, cup-shaped, with dorsomesial distal lobe; chela with palm about 3 / 5 as long as fingers, without sculpture, ventral margin slightly concave, distomesial margin with prominent tooth (Fig. 2 d, e); fingers relatively long, slender, gaping, laterally and mesially with rows of stiff setae along cutting edges, tips crossing. Male minor cheliped similar to female minor cheliped, but with fingers slightly longer and more robust (Figs. 2 f, 5 d, e). Second pereiopod relatively slender; ischium slightly longer than merus; carpus with five articles, with ratios (from proximal to distal) of approximately 5: 3: 1.5: 1.5: 2 (Fig. 3 a, h); chela simple, with fingers subequal to palm; palm as long as distal carpal article. Third and fourth pereiopods similar in shape, length and armature (Fig. 3 b, d); ischium armed with small ventrolateral spine; merus unarmed, about four (P 3) to five (P 4) times as long as wide; carpus unarmed; propodus with five spines along ventral margin and a pair of distal spines (Fig. 3 b – e, i); dactylus simple, conical, not spatulate, gradually curved towards subacute tip, about 0.3 (P 4) to 0.4 (P 3) propodus length (Fig. 3 c, e). Fifth pereiopod much more slender than third and fourth pereiopods; ischium with small ventrolateral spine (Fig. 3 f); merus about six times as long as wide; propodus with four spines on ventral margin (Fig. 3 g), ventrolateral margin with five or six rows of grooming setae (Fig. 3 f, g); dactylus simple, conical, about 0.45 propodus length, with some subdistal setae. Abdominal somites with broadly rounded posteroventral margins; fifth somite with rounded-angular posteroventral margin; sixth segment without articulated flap, posterior margin straight, dorsolateral projections rounded; preanal plate rounded. Male second pleopod with appendix interna subequal to appendix masculina, latter with slender spine-like setae distally and along margin opposed to endopod (Fig. 1 i). Uropod (Fig. 1 f) with protopod bearing distally two strong acute teeth; exopod with diaeresis bearing one subtriangular lateral lobe proximal to distolateral spine and two well-marked rounded lobes at mid-length and mesially (Fig. 1 g); lateral spine relatively strong, elongate; distal margins of exopod furnished with spinules (Fig. 1 g). Telson relatively narrow, tapering towards posterior margin, with two pairs of short dorsal spines inserted at some distance from lateral margins, first pair at about mid-length, second pair at 3 / 4 of telson length (Fig. 1 f); posterior margin broadly rounded, with one pair of small posterolateral spines at each angle, mesial spines being twice as long as lateral spines; anal tubercles well developed. Gill / exopod formula typical for genus: 5 pleurobranchs (P 1 - 5); 1 arthrobranch (Mxp 3); 0 podobranch (Mxp 2); 2 lobed epipods (Mxp 1 - 2), 5 strap-like epipods = mastigobranchs (Mxp 3, P 1 - 4), 5 sets of setobranchs (P 1 - 5); 3 exopods (Mxp 1 - 3). Color. No color notes were made for the four specimens from the Atol das Rocas type series. However, the specimen from Bocas del Toro was photographed alive (11 a-c, 12 b, c) and may be described as following: background mostly semitransparent, with numerous reddish chromatophores forming several diffuse bands, including a broad band running laterally on abdominal pleurae, and interconnecting with broad transverse bands on first, second, fourth, fifth and sixth somites; dorsal portion of carapace speckled with red chromatophores, latter arranged in a transverse band running along posterior margin of carapace and connecting to most-anterior transverse band on abdomen; central dorsal portions of abdominal somites colorless; tail fan, rostral region, antennular and antennal peduncles, and walking legs semitransparent, speckled (more or less densely) with red chromatophores; chelipeds hyaline-grey with red chromatophores arranged in patches and longitudinal bands in some areas, leaving other areas colorless; palm of major chela distally pale orange; fingers of both chelipeds ivory-pinkish (Fig. 11 b, c). Size. The CL of males ranges from 6.7 to 6.8 mm, TL 19.7 to 20.1 mm, respectively; the CL of females ranges from 6.1 to 7.1 mm, TL 17.2 to 22.1 mm, respectively.	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF9FF8437E3F8B3FA5AAE46.taxon	etymology	Etymology. The new species is named after Dr. Martin L. Christoffersen (Universidade Federal de Paraíba, João Pessoa), for his significant contributions to the knowledge of the Brazilian alpheid and other caridean shrimps (see Christoffersen, 1998 and references therein).	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF9FF8437E3F8B3FA5AAE46.taxon	materials_examined	Type locality. Atol das Rocas, Brazil.	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF9FF8437E3F8B3FA5AAE46.taxon	distribution	Distribution. Western Atlantic: presently known only from the type locality, Atol das Rocas, off northeastern Brazil, and Bocas del Toro, Caribbean coast of Panama. Ecology. The Atol das Rocas specimens were collected with the aid of a bait suction pump from burrows on an intertidal sand flat. The Bocas del Toro specimen was collected on a shallow (0.5 – 1.0 m) seagrass sand flat, about 15 m from a sand beach with a few mangrove trees, backed by a peat swamp (Fig. 12 a). It was extracted with a bait suction pump from the possibly U-shaped burrow of a relatively large (body length 95 mm, body diameter 15 mm, proboscis length 10 mm) thalassematid echiuran, Ochetostoma cf. edax (Fisher, 1946) (Fig. 12 b, c).	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF9FF8437E3F8B3FA5AAE46.taxon	description	Taxonomic remarks on host. Ochetostoma edax Fisher, 1946 (identification by G. - V. Murina) was originally described from Baja California in the eastern Pacific (Fisher, 1946) and was previously not known from the Atlantic Ocean (Stephen & Edmonds, 1972). The individual from Bocas del Toro – host of A. christofferseni n. sp. (Fig. 12 b, c) – was extracted with a suction pump from a vertical shaft-like burrow on a seagrass sandflat, whereas all eastern Pacific individuals of O. edax were found in horizontal burrows in muddy sand under rocks (see below). As noted by Anker et al. (2005) for Ochetostoma erythrogrammon Leuckart & Rüppel, 1828, the paucity of morphological, anatomical and color-based characters in species-level taxonomy of the Echiura makes detection of cryptic taxa nearly impossible. Therefore, taxa with pantropical or transisthmian distributions, such as O. erythrogrammon, or O. edax, respectively, should also be examined genetically. For the time being, the Bocas del Toro specimen of Ochetostoma, which appears to be ecologically different from O. edax, is referred to as O. cf. edax, awaiting further taxonomic studies. Variation. The new species appears to be variable in the shape of the rostrum: it may be extremely short and blunt, as in the specimen from Bocas del Toro (Fig. 4 a), broad and triangular, as in the first paratype (Fig. 1 h), or more slenderly triangular, as in the second paratype (Fig. 1 a). The Bocas del Toro specimen also has a much broader telson compared to the Atol das Rocas type specimens (cf. Figs. 1 f, 4 e). A slight variation also exists in the ratio of carpal segments in the second pereiopods (cf. Figs. 3 a, h, 6 a).	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF9FF8437E3F8B3FA5AAE46.taxon	discussion	Remarks. Within the A. barbatus complex, A. christofferseni n. sp. is morphologically most similar to the eastern Pacific A. aequus and to the below described A. naos n. sp. It differs from A. aequus by the presence of a large, acute tooth on the ventromesial margin of the merus of the major chelipeds. Kim & Abele (1988) mentioned in the description of A. aequus that it has “ no spine at distal end ” on the “ inferior inner ” (ventromesial) margin of the merus of the major cheliped. This margin may be at most bluntly projecting, as in the two specimens of A. aequus from Coibita (Fig. 10 b). The homologous tooth on the minor cheliped also separates these two species: it is present, although small, in A. christofferseni n. sp., and absent in A. aequus (Kim & Abele, 1988). Furthermore, A. christofferseni n. sp. differs from A. aequus by the somewhat longer and more slender major chela (cf. Figs. 2 a, b, 5 a, b, 10 b, c). The main differences between A. christofferseni n. sp. and A. naos n. sp. are the length of the stylocerite: not reaching distal margin of first antennular segment in A. christofferseni n. sp. vs. reaching or almost reaching this margin in A. naos n. sp.; and the shape of the rostral carina: very narrow in A. christofferseni n. sp., broader in A. naos n. sp. (cf. Figs. 1 a, 4 a, 7 a). Alpheus christofferseni n. sp. may be separated from the eastern Atlantic A. ribeiroae by the shape of the scaphocerite, with distolateral spine distinctly exceeding the anterior margin of the blade (not exceeding in A. ribeiroae); fingers of the minor chela bearing dense rows of setae (absent in A. ribeiroae); and a stouter major cheliped, which differs in the palm / finger ratio (cf. Anker & Dworschak, 2004). Finally, the western Atlantic species, as well as both eastern Pacific species (see below) differ from the Indo-West Pacific A. barbatus in several characters, e. g., by the proportions of the major chela, the less dense setal brushes on the fingers of the minor chela, and the much more elongate and narrower scaphocerite (cf. Banner & Banner, 1982). The color pattern of A. christofferseni n. sp. appears to be nearly identical to that of A. aequus (cf. Fig. 11), and (although less intense) is also similar to the color pattern of A. naos n. sp. (see below). The only noticeable differences between A. christofferseni n. sp. and A. naos n. sp. is that the posterior dorsal half of the carapace of A. christofferseni n. sp. is covered with small reddish chromatophores (Fig. 11 b), which are absent in A. naos n. sp. (Fig. 11 d). However, in both A. christofferseni n. sp. and A. naos n. sp., the red bands may increase in intensity or fade away (almost disappearing completely, cf. Figs. 11 a, b) depending on the shrimp’s condition, which may be affected by stress, exposure to light, etc. Nomura (2000) attributed a similar color variation in A. barbatus to “ the brightness of the day and night ”. However, the color variation in A. barbatus is more pronounced, especially on the major chela (cf. Nomura, 2000, fig. 1 B, F). Both color and morphological variation in A. barbatus suggest presence of at least two cryptic species in the Indo-West Pacific (A. Anker, pers. obs.). GenBank number. EF 092273 (fcn AA-AC- 41, MNRJ 17926); EF 092274 (fcn 05 - 019, USNM 1100667).	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF0FF9F37E3FA2DFC6EAFE6.taxon	materials_examined	Material examined. 1 male (CL 6.8, TL 20.1), USNM 1100668, Panama, Pacific coast, Amador causeway near Panama City, Punta Culebra, rocky shore, under large mud-covered rocks on muddy sand, in burrow of Listriolobus sp. (host collected and preserved), extreme low tide, 2 Mar 2006, coll., A. Anker and C. Hurt [fcn 06 - 270].	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF0FF9F37E3FA2DFC6EAFE6.taxon	description	Description. Carapace smooth, not setose, laterally not compressed. Rostrum short, subtriangular, distally subacute (Fig. 7 a), slightly descendant and situated below dorsal-most portion of orbital hoods (Fig. 7 b); mediorostral carina feebly marked, blunt, reaching beyond eye level, posteriorly flattening (Fig. 7 a); orbitorostral grooves very shallow; orbitorostral process not conspicuous. Orbital hoods moderately inflated, rounded, unarmed (Fig. 7 a). Pterygostomial angle rounded, not protruding (Fig. 7 b). Branchiostegial margin fringed with setae. Eyes completely concealed in dorsal, lateral and partly frontal view. Ocellar beak welldeveloped, protruding vertically towards rostrum. Epistomial sclerite without projecting tooth. Antennular peduncles moderately stout, second segment slightly longer than dorsally visible portion of first segment, about 1.7 – 1.9 times as long as wide (Fig. 7 a); stylocerite short, distally blunt, almost reaching distal margin of first segment (Fig. 7 a); mesioventral carina of first segment with tooth as illustrated (Fig. 7 c); lateral flagellum without independent secondary ramus, groups of aesthetasc tufts present starting from about ninth segment (Fig. 7 a, b). Antenna with basicerite lacking ventrolateral tooth (Fig. 7 b); carpocerite robust, reaching slightly beyond distal margin of antennular peduncle and scaphocerite; scaphocerite exceeding distal margin of antennular peduncle, with deep cleft between distolateral tooth and blade, lateral margin almost straight (Fig. 7 a), distolateral tooth reaching well beyond anterior margin of blade (Fig. 7 a). Mouthparts (mandible, maxillule, maxilla, first and second maxillipeds) typical for Alpheus. Third maxilliped moderately stout (Fig. 9 a); coxa with lateral plate ear-shaped, distally acute, furnished with some setae; antepenultimate segment flattened, with ventral margin somewhat rugose; ultimate segment very setose; exopod reaching penultimate segment; arthrobranch well-developed (Fig. 9 a). Major cheliped (Fig. 8 a, b) with short, robust ischium; merus stout, about twice as long as wide, dorsal margin distally blunt, not projecting, ventromesial margin finely toothed, distally with small blunt tooth (Fig. 8 a); carpus cup-shaped, without distinct distal lobes; chela ovate, laterally compressed, subrectangular in cross-section; dorsal margin of palm with deep transverse notch subdistally (Fig. 8 a, b), forming a broadly Ushaped groove in dorsal view; mesial face of palm smooth except for small depression near dorsal notch (Fig. 8 b); lateral face with small depression near dorsal notch and broad, very shallow depression extending from base of pollex to about mid-length of palm (Fig. 8 a); slightly more than 1 / 2 length of palm; dactylus with short, distally truncate plunger, latter with stamen-shaped sensillae (Figs. 8 a. b); adhesive discs small (Fig. 8 a). Male minor cheliped (Fig. 8 c – e) with robust merus, more than twice as long as wide; dorsal margin distally unarmed; ventromesial margin straight, distally blunt (Fig. 8 c); carpus short, cup-shaped, with blunt distomesial lobe; chela with palm about 3 / 5 as long as fingers, without sculpture, ventral margin almost straight (Fig. 8 d, e), distomesial margin with promenent blunt tooth (Fig. 8 d); fingers long, slender, slightly gaping, laterally and mesially with rows of stiff setae along cutting edges, tips crossing when chela closed (Fig. 8 d, e). Female minor cheliped unknown. Second pereiopod relatively slender; ischium slightly longer than merus; carpus with five articles, with ratios (from proximal to distal) of approximately 5: 3: 1: 1: 2 (Fig. 9 b); chela simple, with fingers subequal to palm; palm as long as distal carpal article. Third pereiopod (Fig. 9 c) with ischium bearing one ventrolateral spine; merus unarmed, at least five times as long as wide; carpus unarmed; propodus with four slender spines along ventral margin and a pair of distal spines (Fig. 9 c); dactylus simple, conical, not spatulate, gradually curved towards subacute tip, about 1 / 2 propodus length. Fourth pereiopod similar to third. Fifth pereiopod with different article proportions; ischium with ventrolateral spine; propodus with ventral spines and welldeveloped setal brush. Abdominal somites with broadly rounded posteroventral margins; fifth somite with rounded-angular posteroventral margin; sixth segment without articulated flap, posterior margin straight, dorsolateral projections rounded; preanal plate rounded. Male second pleopod (Fig. 7 d) with appendix masculina longer than appendix interna, possibly partly fused to endopod, with slender spine-like setae distally and along endopod-facing margin (Fig. 7 d, e). Uropod (Fig. 7 f) with protopod bearing distally two strong acute teeth; exopod with diaeresis bearing one subtriangular lateral lobe proximal to distolateral spine and two well-marked rounded lobes at mid-length and mesially; lateral spine relatively strong, elongate; distal margins of exopod furnished with spinules (Fig. 7 f). Telson relatively narrow, tapering towards posterior margin (Fig. 7 g), with two pairs of short dorsal spines inserted at some distance from lateral margins, first pair at about mid-length, second pair at 3 / 4 of telson length (Fig. 7 g); posterior margin broadly rounded, with one pair of small posterolateral spines at each angle, mesial spines being at least twice as long as lateral spines (Fig. 7 h); anal tubercles well-developed. Gill / exopod formula as indicated for previous species. Color. Background mostly white semitransparent, with numerous red chromatophores forming several bands, including a broad lateral band on abdominal pleurae, interconnecting with two broad transverse bands on second and fifth somites, and narrow, more irregular bands on first and fourth somites, sixth somite with narrow transverse band along posterior margin; telson and uropods red except for most proximal portions; dorsal portion of carapace with broad band of red chromatophores, descending to flanks; central dorsal portions of abdominal somites, especially third, fourth and sixth, as well as most of posterior and anterior carapace colorless; rostral region, anterolateral margins of carapace and antennular peduncles semitransparent speckled (more or less densely) with red chromatophores; antennal peduncle and walking legs mostly semitransparent white; cheliped merus and carpus hyaline white with red chromatophores; chelae pinkish red due to numerous red chromatophores, distally (proximal to fingers) with pale orange tinge; fingers of major and minor chelae mostly ivory white (Fig. 11 d, e). Size. The CL of the holotype male specimen is 6.8 mm, TL 20.1 mm.	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF0FF9F37E3FA2DFC6EAFE6.taxon	etymology	Etymology. The new species is named after Isla Naos, where the type locality (Punta Culebra) and the Naos Marine Laboratory of the STRI are situated.	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF0FF9F37E3FA2DFC6EAFE6.taxon	materials_examined	Type locality. Punta Culebra, Isla Naos, Amador Causeway near Panama City, Pacific coast of Panama.	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF0FF9F37E3FA2DFC6EAFE6.taxon	distribution	Distribution. Eastern Pacific: presently known only from the type locality on the Pacific coast of Panama. Ecology. The holotype was collected by hand from a burrow of a large thalassematid echiuran (body length 150 mm, body diameter 10 – 15 mm, proboscis length 30 mm), Listriolobus sp. (see below). The burrow was dug horizontally into muddy sand under large mud-covered rocks, in the rocky intertidal, near the extreme low tide mark.	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF0FF9F37E3FA2DFC6EAFE6.taxon	description	Taxonomic remarks on host. The original identification of the host as “ Listriolobus sp. aff. brevirostris Chen & Yeh, 1958 ” was tentative (G. - V. Murina, pers. comm.), partly because of the imperfect condition of the specimen from Punta Culebra (the animal died a few hours prior to preservation). Listriolobus brevirostris was originally described from China (Chen & Yeh, 1958; Stephen & Edmonds, 1972) and is not known to occur in the eastern Pacific. On the other hand, specimens of its congener, Listriolobus cf. bahamensis Fisher, 1926, were recently collected at Punta Culebra and other localities along the Pacific coast of Panama (Murina & Anker, in prep.). They are morphologically (at least externally) and ecologically very similar to the individual found with A. naos n. sp. As no other species of Listrilobus are known from the shallow waters of the tropical eastern Pacific (Stephen & Edmonds, 1972), L. cf. bahamensis may well be the host of A. naos n. sp.	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFF0FF9F37E3FA2DFC6EAFE6.taxon	discussion	Remarks. Within the A. barbatus complex, A. naos n. sp. is morphologically closest to the eastern Pacific A. aequus and the western Atlantic A. christofferseni n. sp. (see above). It differs from A. aequus by the slightly narrower telson; the slightly longer second segment of the antennular peduncle; the broader blade of the scaphocerite; the lack of a slight sinus on the ventral margin of the palm of the minor chela; the less gaping fingers of the minor chela; a different palm / fingers ratio of the major chela; and the distinctly narrower merus of the third pereiopod. For differences between A. christofferseni n. sp. and A. naos n. sp. see remarks under the former species. Another possible difference between these two species may lie in the appendix masculina: its proximal half is apparently partly fused to the endopod in A. naos n. sp. (Fig. 7 e), whereas the entire appendix masculina is free-standing in A. christofferseni n. sp. (Figs. 1 i, 6 e) All these features, however, need to be confirmed by observations in additional specimens. GenBank number. EF 092275 (fcn 06 - 270, USNM 1100668).	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFEBFF9D37E3FA87FC50ACC0.taxon	materials_examined	Material examined. 1 female (CL 4.7, TL 14.3), MNHN-Na 16388, Panama, Coiba Marine National Park, Coibita, mud-rock intertidal, under rock, in burrow of Ochetostoma edax (host collected and preserved), extreme low tide, 20 Mar 2007, coll. A. Anker, I. Marin, J. Jara, E. Gómez and E. Tóth [fcn 07 - 109]; 1 ovig. female (CL 4.9, TL 14.3), MNHN-Na 16389, Panama, Coiba Marine National Park, Coibita, mud-rock intertidal near STRI station, under rock, in burrow of Ochetostoma edax (host collected and preserved), extreme low tide, 22 Mar 2007, coll. A. Anker [fcn 07 - 177].	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFEBFF9D37E3FA87FC50ACC0.taxon	description	Description. For detailed description see Kim & Abele (1988). Color. Mostly ivory-whitish with pinkish tinge in some areas due to presence of scattered reddish chromatophores (Fig. 11 f); one female had yellow-orange eggs. Size. The CL of the two females is 4.7 mm and 4.9 mm, the TL for both is 14.3 mm. The single male originally reported by Kim & Abele (1988) had a CL of 4.3 mm, whereas the two females both had a CL of 6.8 mm. Ramos’ (1995) three specimens were smaller, with 2.9 mm CL in the single male and 4.3 – 4.4 mm in the two females. Based on these data, the CL of adult A. aequus ranges from 2.9 to 6.8 mm.	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFEBFF9D37E3FA87FC50ACC0.taxon	materials_examined	Type locality. Playa Blancas, Costa Rica (Kim & Abele, 1988).	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFEBFF9D37E3FA87FC50ACC0.taxon	distribution	Distribution. Eastern Pacific: Costa Rica: Playa Blancas; Galapagos: Santa Fe (Kim & Abele, 1988); Panama: Coibita (Coiba Marine National Park) (present study); Colombia: Gorgona Island (Ramos, 1995). Ecology. The habitat of the holotype from Playa Blancas, Costa Rica, was described as “ shore to 5.0 m; shale beach ” and “ shale beach between beach and rocky reef ” (Kim & Abele, 1988). Other alpheids collected in this area were Alpheus fasciatus Lockington 1878 (reported as A. paracrinitus Miers, 1888) and A. galapagensis Sivertsen, 1933 (reported as A. canalis Kim & Abele, 1988). The two specimens from Santa Fe (Barrington) Island, Galapagos, were collected while “ diving in bay, [at] about 5 m ”. Other alpheids occurring in this locality were Alpheus bellimanus Lockington, 1878 and A. rostratus Kim & Abele, 1988. Ramos’ (1995) specimens came from a tidal beach with coral sand (“ playas de arena coralina ”). No particular associations were noted by Kim & Abele (1988) or Ramos (1995). In contrast, the two Panamanian specimens of A.	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
038E6046FFEBFF9D37E3FA87FC50ACC0.taxon	description	aequus were found associated with medium-sized (body length 28 mm, diameter 11 – 12 mm, proboscis length 15 mm, proboscis diameter 3 – 5 mm) thalassematid echiurans, Ochetostoma edax (Fisher, 1926) (Fig. 12 e) in a mixed mud-rock intertidal of Coibita (Fig. 12 d). The burrows of O. edax are smoothly lined horizontal tunnels dug in muddy sand under partly mud-embedded rocks. The shrimps were observed sitting just next to their hosts. Notably, in both cases, only one shrimp per host was found, despite some efforts to find its potentially present mate by prospecting the immediate vicinity of the burrow. Taxonomic remarks on host. The finding of two specimens of Ochetostoma edax (identification by G. - V. Murina) at Coibita represents a considerable extension of the distribution range of this species from Baja California to Panama. The identity of O. cf. edax from the Atlantic (Caribbean) coast of Panama remains to be determined (see above). Variation. The two female specimens from Coibita agree well with the description and illustrations of A. aequus provided by Kim & Abele (1988), except for the length of the dactylus of the major chela, which reaches only slightly beyond the tip of the pollex in the Coibita specimens, and distinctly beyond the pollex in the holotype (cf. Kim & Abele 1988, fig. 23). GenBank number. EU 084881 (fcn 07 - 109, MNHN 16388).	en	Anker, Arthur, Hurt, Carla, Knowlton, Nancy (2007): Three transisthmian snapping shrimps (Crustacea: Decapoda: Alpheidae: Alpheus) associated with innkeeper worms (Echiura: Thalassematidae) in Panama. Zootaxa 1626: 1-23, DOI: 10.5281/zenodo.179290
