Salmoneus wehrtmanni, Anker, 2010

Anker, Arthur, 2010, The shrimp genus Salmoneus Holthuis, 1955 (Crustacea, Decapoda, Alpheidae) in the tropical western Atlantic, with description of five new species *, Zootaxa 2372 (1), pp. 177-205 : 193-197

Salmoneus wehrtmanni sp. nov.

( Figs. 10–11 , 12a , 13b , 14d )

Type material. Holotype: breeding female (cl 5.0 mm, tl 14.0 mm), USNM 1124215 , Panama, Caribbean coast, Isla Grande, southern shore, under rocks and rubble on sand, near seagrass, 0.5–1 m depth, leg. A. Anker, 21.IV.2006 [fcn 06-395] . Paratypes: 1 breeding female (cl 4.2 mm, tl not measured), FLMNH UF Arthropoda 15019, Panama Caribbean coast, Isla Grande, off west point, under rock, 1.5 m depth, leg. A. Anker, 15.IX.2007 [fcn 07-252]; 1 non-breeding specimen (cl 3.3 mm, tl 9.0 mm), USNM 1124216 , Panama, Caribbean coast, Isla Grande, northeastern (sea side) shore, shallow bay below light house, 0.5 m depth, under rocks/rubble, leg. A. Anker, 5.IX.2006 [fcn 06-448, dissected]; 1 non-breeding specimen (cl 2.7 mm, tl 7.3 mm), USNM 1124217 , same collection data as previous specimen [fcn 06-449] .

Additional material examined. 1 non-breeding specimen (cl 3.7 mm), USNM 1124218 , Panama, Caribbean coast, Bocas del Toro, Isla Colón, Boca del Drago , under rocks on sand, 0.7–1.5 m depth, leg. A. Anker, 11.XI.2006 [fcn 06-618]; 2 breeding females (cl 2.3 mm, 2.4 mm), UP, Panama, San Blas Islands, small cay in the Cayos Los Grullos NE of Cartí Suitupo, 0.5–1.5 m depth, under rocks on coarse sand, leg. A. Anker & I. Marin, 22. V.2007 [fcn 07-178]; 1 breeding female (cl 3.0 mm), USNM 1124219 , Panama, Caribbean coast, La Guaira, in or under coral rocks, 0.5–1 m depth, leg. A. Anker, 4.VIII.2007 [fcn 07-213]; 1 breeding female (cl 4.9 mm, tl 12.3 mm), OUMNH 2007-20 - 149 , Honduras, Utila, Little Bight , 16°04.757'N 86°55.757'W, hand collecting, under rocks, 10 m depth, leg. A. Anker & S. De Grave, 8.VII.2007 ; 1 breeding female (cl 5.1 mm), USNM 136103 , Mexico, Caribbean coast, Yucatan, Quintana Roo, Bahía de Ascensión, behind central part of Nicchehabin Reef , Smithsonian-Bredin Expedition St. 82–60, 0.6–1.3 m depth, leg. W.L. Schmitt, E.L. Bousfield & H.A. Rehder, 16.IV.1960 [with note “infested with abdominal bopyrid”, latter apparently removed]; 1 breeding female (cl 4.0 mm), USNM 136106 , Mexico, Caribbean coast, Yucatan, Quintana Roo, Bahía de Ascensión, Nicchehabin Reef , turtle grass and Porites clumps, Smithsonian-Bredin Expedition St. 91–60, leg. F.C. Daiber, E.L. Bousfield & R. L. Haynes, 18.IV.1960 ; 1 non-breeding subadult specimen (cl 2.1 mm), USNM 1125418 , Tobago, Sandy Bay , St. 5, rock washing, leg. R. Heard, 7.IV.1992 ; 1 breeding female (cl 3.2 mm), 1 non-breeding specimen (cl 3.4 mm), USNM 1125419 , Tobago, Lovers Beach, St. 3, leg. R. Heard, 6.IV.1992 .

Description. Carapace with numerous scattered setae ( Figs. 10a–b , 12a ). Rostrum triangular in dorsal view, usually as long as broad at base, reaching well beyond mid-length of second segment of antennular peduncle, tip acute or subacute ( Figs. 10a , 12a ); lateral margins nearly straight; ventral margin unarmed ( Fig. 10b ); rostral carina well marked, extending beyond level of eyes posteriorly, areas lateral to rostral carina shallowly depressed ( Figs. 10a , 12a ). Orbital teeth strong, acute ( Figs. 10a , 12a ). Pterygostomial margin not protruding anteriorly, rounded-angular ( Fig. 10b ). Eyes completely concealed in dorsal and lateral views ( Figs. 10a–b , 12a ); cornea well developed; anteromesial margin of eyestalk not especially projecting.

Antennule with stylocerite distinctly overreaching distal margin of second peduncular segment, with acute tip; ventromesial carina of first segment with small sharp tooth ( Fig. 10c ); second segment not elongate, wider than long ( Fig. 10a ); lateral flagellum bifurcating at second segment, secondary ramus well developed, with several groups of aesthetascs ( Fig. 10a ). Antenna with basicerite bearing stout acute distoventral tooth ( Fig. 10b ); scaphocerite broadly ovate, with strong acute distolateral tooth and broad blade, latter with feebly convex anterior margin ( Fig. 10a ); carpocerite short, not reaching mid-length of scaphocerite.

Third maxilliped with short, rounded lateral plate; ultimate segment tapering, tip with small spines ( Fig. 10d ).

Chelipeds strongly asymmetrical in shape, unequal in size ( Figs. 11a, d ). Major cheliped ( Figs. 11a–c ) with ischium unarmed; merus inflated, especially distally, excavated ventrally; carpus somewhat elongate, with depressed ventral margin; chela stout, with fingers slightly longer than half-length of palm; palm conspicuously flattened ventromesially, more excavated proximally, sparsely setose; fingers rather stout, straight except for curved crossing tips, cutting edges serrated, with around 10 subtriangular to rounded teeth ( Fig. 11c ). Minor cheliped ( Fig. 11d ) with ischium subequal to merus, unarmed; carpus 0.8 length of merus, cylindrical, widening distally; chela small, simple, with fingers shorter than palm, cutting edges unarmed.

Second pereiopod ( Fig. 10e ) relatively short, slender; ischium unarmed; merus shorter than ischium; carpus five-segmented, first segment approximately equal to sum of third, fourth and fifth segments. Third pereiopod ( Fig. 10f ) slender; ischium with one ventrolateral spine; merus about five times as long as wide; carpus with small distoventral spinule; propodus with three small ventral spinules and longer and stouter distal spinule(s); dactylus simple, conical, moderately slender, slightly less than half-length of propodus. Fourth pereiopod similar to third. Fifth pereiopod with ischium unarmed; propodus with setal brush distally.

First to third pleura rounded; fourth pleuron ending posteriorly in blunt angle; fifth pleuron forming blunt angle posteroventrally ( Fig. 10g ); sixth pleurite without distinct articulated plate, however, feeble suture delimiting subtriangular posteroventral projection; preanal plate triangular, rounded distally. Telson ( Fig. 10j ) about twice as long as wide proximally, tapering posteriorly, with two pairs of dorsal spines situated first at or slightly posterior to telson mid-length, second at about 0.8 telson length; posterior margin straight in dorsal view, central portion with inconspicuous, broadly V-shaped incision (better visible in ventral view) and three pairs of thick plumose setae, latter fringed by two pairs of spines, lateral being only half as long and less than stout than mesial.

Second pleopod with appendix masculina slightly shorter than appendix interna, furnished with stout setae apically and on inner margin ( Fig. 10h ). Uropod ( Fig. 10i ) with narrow exopod and endopod; diaeresis sinuous; both distolateral tooth and adjacent distolateral spine very stout.

Gill/exopod formula typical for genus (see under first species).

Size. cl 2.3–5.0 mm, tl of largest specimens: 14.0 mm (holotype), 12.3 mm (breeding female from Utila).

Colour in life. Semitransparent, milky white, with slight pale tinge and hyaline chelae; embryos yellow ( Fig. 14d ).

Etymology. Named for Ingo S. Wehrtmann (Universidad de Costa Rica), a good friend and colleague, and a specialist of reproduction in decapods and other crustaceans.

Type locality. Isla Grande, Panama.

Distribution. Presently known from several localities on the Caribbean coast of Panama (Isla Grande, La Guaira, San Blas Islands, Bocas del Toro), Honduras (Utila), Mexico (Quintana Roo), and Tobago.

Ecology. Near-shore silty sandy flats, often near seagrass and mangrove roots, under rocks and rubble at shallow depths (0.5–1.5 m).

Variation. The specimen from Utila agrees well with the specimens from Panama except for a small difference in the length of the posterior spines on the telson: in the Utila specimen, both pairs are stout and subequally long (S. De Grave, pers. comm.), whereas in the holotype, the lateral spines are significantly shorter and slenderer ( Fig. 10j ). The Quintana Roo and Tobago specimens show some variation in the length of the rostrum and strength and direction of the orbital teeth. In smaller specimens, the rostral carina is usually less distinct.

Remarks. Salmoneus wehrtmanni sp. nov. is belongs to the exclusively American S. ortmanni species group ( Anker & Marin 2006; see also above), being closely related to the other two species of this group, S. ortmanni and S. carvachoi . Rankin’s type of S. ortmanni (originally described as “ Athanas ortmanni ”) from Nassau in the Bahamas is nowhere to be found. Rankin’s single figure of S. ortmanni is just informative enough to know that it is distinct from S. carvachoi (see Anker 2007).

Anker (2007) provided illustrations of S. ortmanni from Atol das Rocas off NE Brazil, which agree well with figures provided by Schmitt (1936: figs. 2i, h; frontal margin, reproduced here in Fig. 12f ) and Banner & Banner (1981: figs. 7h–k, major cheliped). Without the type specimen or topotypical specimens at hand, it seems most reasonable to accept the identity of S. ortmanni sensu Rankin (1898) as the most common and widespread species in reef, lagoon and shore habitats of the tropical western Atlantic, ranging from Bermuda south to Brazil and throughout the Caribbean, and therefore, there would seem to be little doubt that specimens illustrated by Schmitt (1936) and Anker (2007) were correctly identified as S. ortmanni .

The morphological differences between S. ortmanni and S. wehrtmanni sp. nov. are rather slight and can only be seen in adult specimens. In S. ortmanni , the basal portion of the lateral margin of the rostrum, as seen in dorsal view, is slightly convex, whilst the rostral carina is either absent or extends only to the level of the eyes. In contrast, in S. wehrtmanni sp. nov., the lateral margin is either straight proximally or broadly and slightly concave from the base of the rostrum all the way to the tip, whilst the rostral carina is stronger and reaches well beyond the eyes. In addition, the area adjacent to the rostral carina is not depressed in S. ortmanni , but is shallowly depressed in S. wehrtmanni sp. nov.; especially in larger specimens (compare Figs. 10a , 12a, 12b–d ; see also Anker 2007: fig. 1b). The orbital teeth appear to be somewhat stronger in S. wehrtmanni sp. nov. (compare Figs. 12a and 12b–d ).

Some other differences between the two species were initially recorded while comparing side by side the Panamanian specimens of S. ortmanni and S. wehrtmanni sp. nov. However, these differences appear to be more ambiguous, especially when material from other places is included. For instance, in S. ortmanni , the posterior margin of the telson bears a rather conspicuous, more or less U-shaped notch ( Anker 2007, fig. 1j); in S. wehrtmanni sp. nov., this margin appears to be straight in dorsal view ( Fig. 10i ), although observed in ventral view, it actually has a very shallow, broadly triangular incision (obscured by three pairs of plumose setae). In some specimens of S. wehrtmanni sp. nov., the first carpal segment is about four times as long as wide ( Fig. 10e ), whereas in all S. ortmanni , the first carpal segment is always around six times as long as wide ( Fig. 13a ; see also Anker 2007, fig. 1f). However, in some specimens from Yucatan assigned here to S. wehrtmanni sp. nov., this ratio approaches that of S. ortmanni , although the entire second pereiopod appears to be slightly more robust than in S. ortmanni ( Fig. 13 ). Another possible difference between S. wehrtmanni sp. nov. and S. ortmanni lies in the carapace pilosity: S. wehrtmanni sp. nov. has distinctly more short stubby setae on the carapace ( Fig. 10b ) than S. ortmanni , in which the carapace bears relatively few setae, and at first glance appears almost glabrous ( Figs. 12b–c ). Interestingly, this distinction is only very clear in the Panamanian material; for instance, in the Bermuda specimen identified here as S. ortmanni based on the shape of the frontal margin, the carapace is covered by conspicuous setae; these setae are also present in the Atol das Rocas specimens ( Anker 2007, fig. 1c).

Importantly, on the Caribbean coast of Panama, where fresh material of both S. wehrtmanni sp. nov. and S. ortmanni was available, these two species can be easily distinguished when alive: the former species is pale milky white ( Fig. 14d ), whereas the latter species is uniform yellow-orange ( Fig. 14e ). Both S. ortmanni and S. wehrtmanni sp. nov. may occur sympatrically in similar habitats — shallow back reef flats with abundant rocks and rubble, often with Thalassia . Interestingly, in Bocas del Toro where both species occur, they were always collected at different locations: S. wehrtmanni sp. nov. at sand-rubble patches of Boca del Drago, with more fine sediments, and S. ortmanni at the more exposed and rockier parts of Playa Bluff.

Salmoneus carvachoi differs from both S. ortmanni and S. wehrtmanni sp. nov. in the long slender dactyli on the third to fifth pereiopods (see Anker 2007: fig. 3k) and also in its banded colour pattern ( Fig. 14f ). In addition, S. carvachoi usually occurs on silt- and mud-type bottoms, e.g. in mangrove and estuarine habitats.

Figures

FIGURE 10. Salmoneus wehrtmanni sp. nov., paratype, non-breeding specimen from Isla Grande, Panama (USNM 1124216): a, frontal region, dorsal; b, same, lateral; c, tooth on ventromesial carina of first segment of antennular peduncle; d, third maxilliped, lateral; e, second pereiopod, lateral; f, third pereiopod, lateral; g, posterior pleurites and tail fan (setae omitted), lateral; h, second pleopod; i, uropod, dorsal; j, telson, dorsal. Scale bars = 1 mm.

FIGURE 11. Salmoneus wehrtmanni sp. nov., paratype, non-breeding specimen from Isla Grande, Panama (USNM 1124216): a, major chela, lateral; b, same, mesial; c, same, chela, “lateral”; d, minor cheliped, lateral. Scale bars = 1 mm.

FIGURE 12. Salmoneus wehrtmanni sp. nov.: a, holotype, breeding female from Isla Grande, Panama (USNM 1124215), rostro-orbital region of carapace, dorsal. Salmoneus ortmanni (Rankin, 1898): b, breeding female from Isla Grande, Panama (UP), frontal region, dorsal; c, breeding female from Portobelo, Panama (USNM 1124220), rostroorbital region of carapace, dorsal; d, non-breeding specimen from Cahuita, Costa Rica (FLMNH UF Arthropoda 18688), rostro-orbital region of carapace, dorsal; e, breeding female from Bermuda (USNM 1125420), frontal region, dorsal; f, another specimen from Bermuda, frontal region, dorsal (after Schmitt 1936). Scale bars: c = 0.5 mm, a, b, d, e = 1 mm, f without scale.

FIGURE 13. Salmoneus ortmanni (Rankin, 1898), breeding female from Bermuda (USNM 1125420): a, second pereiopod, lateral. Salmoneus wehrtmanni sp. nov., breeding female from Bahía de Ascensión, Mexico (USNM 136103): b, second pereiopod, lateral. Scale bar = 1 mm.

FIGURE 14. Habitus and live colour pattern of some western Atlantic species of Salmoneus Holthuis, 1955: a, S. armatus sp. nov., holotype, Isla Grande, Panama (USNM 1124209); b, S. camaroncito sp. nov., holotype, Isla Grande, Panama (USNM 1124211); c, S. degravei sp. nov., holotype from Isla Grande, Panama (USNM 1124213); d, S. wehrtmanni sp. nov., holotype from Isla Grande, Panama (USNM 1124215); e, S. ortmanni (Rankin, 1898), nonbreeding specimen from Bocas del Toro, Panama (USNM 1124221); f, S. carvachoi Anker, 2007, non-breeding specimen, Timbó River, Pernambuco, Brazil (MZUESC 1340) (a–e photographs by the author; f photograph by Alexandre Oliveira de Almeida).