Salmoneus alvarezi, Anker, Arthur & Lazarus, Juan Felipe, 2015

Anker, Arthur & Lazarus, Juan Felipe, 2015, On two new species of the shrimp genus Salmoneus Holthuis, 1955 (Decapoda, Caridea, Alpheidae) from the tropical eastern Pacific, Zootaxa 3957 (5), pp. 520-534 : 521-526

Salmoneus alvarezi sp. nov.

( Figs. 1–3 )

Salmoneus ortmanni — Ríos & Carvacho 1983: 462; Christoffersen & Ramos 1988: 63; Villalobos-Hiriart et al. 1989: 16; Ríos 1989: 154, pl. 30; Wicksten 1991: 151; Ríos 1992: 7; Villalobos-Hiriart et al. 1992: 6; Villalobos 2000: 74, fig. 37; Lazarus-Agudelo & Cantera-Kintz 2007: 228 [not S. ortmanni ( Rankin, 1898) ].

(?) Salmoneus ortmanni — Flores-Hernandez 1991: 132; Wicksten & Hendrickx 1992: 6; Hendrickx 1993: 6; Hendrickx 1995: 433; Wicksten & Hendrickx 2003: 66 [not S. ortmanni ( Rankin, 1898) ].

Salmoneus cf. ortmanni — Anker 2010: 201 [not S. ortmanni ( Rankin, 1898) ].

Type material. Colombia. Holotype: ov. specimen (cl 4.2 mm), INV CRU8365, Bahía Málaga, Curichichi, 03°59’37.8”N 77°19’03.9”W, intertidal mudflat exposed at low tide, under rocks, coll. A. Anker, 26.iv.2009 [fcn COL-00176]. Paratypes: 1 non-ov. specimen (cl 3.0 mm), INV CRU8366, Bahía Málaga, Los Negros, 03°59’N 77°17”W, rocky intertidal, under large rocks on muddy sand, coll. A. Anker, 25.iv.2009 [fcn COL-00146]; 1 ov. specimen (cl 3.0 mm), MZUSP 33198, Bahía Málaga, Naidizal, 04°02’34.3”N 77°13’48.4”W, rocky intertidal exposed at low tide, under rocks in muddy water (near water edge), hand sieve, coll. A. Anker, 23.iv.2009 [fcn COL-00030]; 1 ov. specimen (cl 4.1 mm), MZUSP 33199, same collection data [fcn COL-00017]; 1 ov. specimen (cl 4.0 mm), 1 non-ov. specimen (cl 3.1 mm), OUMNH.ZC. 2015.01.0 88, same collection data [fcn COL-00012]; 1 ov. specimen (cl 4.2 mm), OUMNH.ZC. 2015.01.0 89, same collection data [fcn COL-00018].

Additional material. Costa Rica. 1 ov. specimen (cl 4.0 mm), MZUSP 33200, Punta Morales, Playa Blanca, muddy-rocky intertidal near mangrove, under rocks, coll. A. Anker, 22.xi.2005 [fcn 05-112]; 1 ov. specimen (cl 4.4 mm), OUMNH.ZC. 2015.01.0 90, same collection data [fcn 05-113].

Description. Carapace with numerous scattered setae ( Fig. 1 B). Rostrum subtriangular in dorsal view, about as long as broad at base, reaching beyond distal margin of first article of antennular peduncle, typically not reaching mid-length of second article, with acute tip; lateral margins slightly convex proximally; ventral margin distally unarmed; rostral carina present as low keel extending beyond level of eyes posteriorly; areas lateral to rostral carina shallowly depressed ( Fig. 1 A, B). Orbital teeth strong, acute, directed anteriorly ( Fig. 1 A, B). Pterygostomial margin feebly protruding anteriorly, rounded ( Fig. 1 B).

Eyes completely concealed in dorsal view, anterior-most portion often visible in lateral view; anteromesial margin of eyestalk not markedly projecting, rounded; cornea well developed ( Fig. 1 A, B). Epistomial sclerites each with small sharp tooth.

First to third pleura rounded posteroventrally; fourth pleuron with blunt posteroventral angle; fifth pleuron with posteroventral angle produced into small tooth; sixth somite without articulated plate ( Fig. 1 C); preanal plate rounded distally. Telson about 2.2–2.3 times as long as wide proximally, tapering posteriorly, with two pairs of strong dorsal spiniform setae situated at about 0.5 and 0.75 of telson length, respectively; posterior margin nearly straight or shallowly emarginated centrally, with two pairs of stout spiniform setae, lateral shorter and noticeably more slender than mesial, and two pairs of long plumose setae between mesial spiniform setae ( Fig. 1 D, E).

Antennule robust; stylocerite distinctly overreaching distal margin of second article, with acute tip; ventromesial carina of first article with sharp, anteriorly directed tooth; second article about as long as wide; lateral flagellum bifurcating at about third or fourth segment, secondary ramus well developed, with several (typically six) groups of aesthetascs ( Fig. 1 A, B). Antenna with basicerite bearing sharp distoventral tooth; scaphocerite broadly ovate, with strong acute distolateral tooth and relatively broad blade, latter with convex anterior margin reaching slightly beyond distolateral tooth; carpocerite short, not reaching beyond mid-length of scaphocerite ( Fig. 1 A, B, F).

Mouthparts not specific, typical for genus. Third maxilliped with rounded lateral plate; ultimate article tapering distally, ending in small corneous, apparently immovable spine, distodorsal surface with several movable spiniform setae ( Fig. 1 G, H).

Chelipeds strongly asymmetrical in shape and unequal in size; major cheliped by far most conspicuous in general view ( Figs. 2 , 3 ). Major cheliped with ischium unarmed, depressed ventrally; merus strongly inflated, widening distally, excavated ventrally (especially distally), with shallow depression distodorsally; carpus moderately long, with depressed ventral margin; chela stout, with fingers about 0.5 length of palm; palm conspicuously flattened ventromesially, excavated ventrally, distoventral area forming short shoulder; fingers moderately stout, with strongly curved, crossing tips; cutting edges of both fingers with about 10 subtriangular or rounded teeth extending from finger base to 0.8–0.9 of finger length ( Fig. 2 C–D). Minor cheliped with ischium shorter than merus, unarmed; merus equal to carpus; carpus cylindrical, widening distally; chela small, simple, with fingers equal to palm, slightly gaping; finger cutting edges unarmed ( Fig. 2 E, F).

Second pereiopod relatively short, slender; ischium unarmed; merus longer than ischium; carpus five-jointed, first joint slightly longer than sum of remaining joints ( Fig. 1 I). Third pereiopod moderately slender; ischium typically with two spiniform setae on ventrolateral surface, sometimes with one spiniform seta; merus about five times as long as wide; carpus with slender distoventral spiniform seta; propodus with three slender spiniform setae on ventral margin and pair of longer and stouter spiniform setae adjacent to dactylus; dactylus slightly more than 0.5 length of propodus, moderately slender, conical, simple, slightly curving distally ( Fig. 1 J). Fourth pereiopod generally similar to third; ischium typically unarmed, sometimes with one small spiniform seta on ventrolateral surface ( Fig 1 K). Fifth pereiopod longer and more slender than third; ischium shorter than that of third pereiopod, unarmed; merus subequal to carpus; propodus with at least three slender spiniform setae on ventral margin and well-developed setal brush distally ( Fig. 1 L).

Second pleopod with appendix masculina slightly longer than appendix interna, with stiff setae on and near apex ( Fig. 1 M). Uropod with moderately narrow exopod and endopod; diaeresis sinuous, with subtriangular distolateral tooth adjacent to stout distolateral spiniform seta ( Fig. 1 N, O).

Gill/exopod formula typical for genus (see Anker 2010).

Colouration. Uniform bright yolk-yellow to yellow-orange; antennular and antennal flagella, second to fifth pereiopods, and pleopods pale straw-yellow; major chela fingers hyaline-whitish; ovaries orange-red ( Fig. 3 ).

Etymology. The new species is named after our colleague, Dr. Fernando Alvarez (Universidad Nacional Autónoma de México), in recognition of his numerous contributions to the crustacean fauna of Mexico and Central America.

Type locality. Bahía Málaga, Colombia.

Distribution. Tropical eastern Pacific from northern Gulf of California to Colombia and Galapagos. Specific localities include Mexico: Laguna Percebú (near San Felipe), Isla Tiburón, Río Mulegé, Bahía Concepción, southern Baja California ( Ríos & Carvacho 1983; Villalobos-Hiriart et al. 1989, 1992; Ríos 1989, 1992; Villalobos 2000, all as S. ortmanni ); Costa Rica: Punta Morales (present study); Colombia: Isla Playa Blanca near Ensenada de Utria (Chocó) ( Christoffersen & Ramos 1988, as S. ortmanni *), Bahía Málaga (present study); Ecuador: Galapagos Archipelago: Gordon Rocks, Post Office Bay, Bahía Gardner ( Wicksten 1991; Wicksten & Hendrickx 2003, as S. ortmanni *) [*tentative re-assignment of records, see below].

Ecology. Rocky and rocky-sandy intertidal, sometimes with silt or mud component, occasionally also on rocky shores near mangroves or in estuarine conditions; typically found under rocks on coarse or fine sand, presumably free-living.

Remarks. Salmoneus alvarezi sp. nov. is morphologically closest to the western Atlantic S. ortmanni and S. wehrtmanni . The new species differs from S. ortmanni by the noticeably depressed rostro-orbital area (not particularly depressed in S. ortmanni ); the feebly emarginated posterior margin of the telson (more deeply incised in S. ortmanni ); the longer carpus of the minor cheliped; the longer propodus and more slender dactylus of the third pereiopod; and the slightly longer stylocerite, distinctly overreaching the distal margin of the second article of the antennular peduncle (barely reaching or slightly overreaching this margin in S. ortmanni ) (cf. Figs. 1 , 2 and Anker 2007: figs. 1, 2). The new species can be also separated from S. wehrtmanni , for instance, by the broadly convex lateral margins of the rostrum (slightly concave to nearly straight in S. wehrtmanni ); the distally wider merus of the major cheliped; and in life, by the bright yellow-orange colour (white in S. wehrtmanni ) (cf. Figs. 1–3 and Anker 2010: 10, 11, 14d). In S. wehrtmanni , the first carpal article of the second pereiopod may be either longer (as in S. alvarezi sp. nov.) or shorter than the sum of the remaining articles ( Anker 2010: figs. 10e, 13b); therefore, this character cannot be used in the separation of the two species. Salmoneus alvarezi sp. nov. is more distantly related to S. carvachoi from the western Atlantic and its below-described sister species from the eastern Pacific, both differing from the new species by several morphological characters, colour pattern and habitat (see below).

All previous records of S. ortmanni from the eastern Pacific (e.g., Ríos & Carvacho 1983; Christoffersen & Ramos 1988; Villalobos-Hiriart et al. 1989; Wicksten 1991; Ríos 1992) are reassigned to S. alvarezi sp. nov., based on illustrations in Ríos (1989) and Villalobos (2000), morphological notes and colour description in Ríos (1992) and some ecological data in Christoffersen & Ramos (1988) and Wicksten (1991). Ríos (1992) stated that the only consistent difference between his specimens from the northern and central Gulf of California (Laguna Percebú, Río Mulegé and Bahía Concepción) and the Caribbean ( Guadeloupe, most likely Carvacho’s (1979) material) and Brazilian specimens (fide Christoffersen 1982) was the absence of a spiniform seta on the ischium of the second pereiopod in the former specimens. However, the material from Guadeloupe reported by Carvacho’s (1979) as S. ortmanni , as well as Christoffersen’s (1982) material of S. ortmanni from Brazil, was later re-identified as S. carvachoi by Anker (2007). Thus Ríos (1992) comparative material of S. ortmanni from Guadeloupe was most likely S. carvachoi and not S. ortmanni sensu Rankin (1898) .

Ríos (1992) noted that the colour in life of the Bahía Concepción specimens was “brilliant greenish yellow”. Since the unarmed ischium of the second pereiopod and the uniform bright yellow colour represent two key characters separating S. alvarezi sp. nov. from the below described S. malagensis sp. nov., the specimens from the Gulf of California reported as S. ortmanni by Ríos (1989, 1992), Villalobos-Hiriart et al. (1989) and Villalobos (2000) are reassigned to S. alvarezi sp. nov. Records of S. ortmanni in several regional checklists (e.g. Wicksten & Hendrickx 1992, 2003) most likely also refer to S. alvarezi sp. nov.

Christoffersen & Ramos’ (1988) material of S. ortmanni from Isla Playa Blanca, Colombia, was collected in the intertidal coralline sand, adjacent to large and small rocks, a habitat more typical of S. alvarezi sp. nov. than S. malagensis sp. nov., which was collected from burrows on a tidal mudflat (see below). Wicksten (1991) did not provide direct notes on the habitat of S. ortmanni in the Galapagos localities, but a brief analysis of the syntopical decapod fauna at the collection stations suggests an intertidal or shallow subtidal rocky-sand bottom, which is much more typical of S. alvarezi sp. nov. Therefore, Christoffersen & Ramos’ (1988) and Wicksten’s (1991) records from Colombia and Galapagos, respectively, are tentatively re-assigned to S. alvarezi sp. nov.

Figures

FIGURE 1. Salmoneus alvarezi sp. nov., holotype from Bahía Málaga, Colombia (INV CRU 8365): A—frontal region, dorsal; B—same, lateral; C—posterior abdominal somites, lateral; D—telson, dorsal; E—same, posterior margin, dorsal; F—antennal scaphocerite, dorsal; G—third maxilliped, lateral; H—same, tip of ultimate article, dorsomesial; I—second pereiopod, lateral; J—third pereiopod, lateral; K—fourth pereiopod, lateral; L—fifth pereiopod, lateral; M—second pleopod, detail of appendices masculina and interna, mesial; N—uropod, dorsal; O—same, detail of distolateral area of exopod, dorsal. H drawn without scale.

FIGURE 2. Salmoneus alvarezi sp. nov., holotype from Bahía Málaga, Colombia (INV CRU 8365): A—major cheliped, lateral (mastigobranch detached); B—same, mesial; C—same, unfolded, detail of merus and carpus, lateral; D—same, chela, lateral; E—minor cheliped, lateral; F—same, chela, mesial.

FIGURE 3. Salmoneus alvarezi sp. nov., living specimens: A, B—paratype, ov. specimen from Bahía Málaga, Colombia (OUMNH. ZC. 2015.01.089); C, D—non-type, ov. specimen from Punta Morales, Costa Rica (OUMNH. ZC. 2015.01.090); A, C—dorsal view; B, D—lateral view. Photographs by A. Anker.