Leptalpheus pereirai Anker & Caripe, 2016, sp. nov.

Leptalpheus pereirai sp. nov. (Figs. 1–4) Leptalpheus sp. 1 — Anker 2011: 24, figs. 18 A–E, 19 A, B. Type material. Panama, Caribbean coast: holotype, 1 male (cl 7.2 mm), MZUSP 34067, Bocas del Toro, Isla Colón, STRI Bay, near STRI dock, 9.351516 -82.257716, shallow subtidal sea grass flat near mangrove, depth: 0.5–1.5 m, in burrows, suction pump, leg. A. Anker, 03.v. 2015; paratypes: 1 female (cl 5.5 mm), MZUSP 34068, between Colón and Portobelo, near Mechi, 9.491252 -79.709096, shallow pools on sand flat exposed at low tide, fringed by sea grass, near fossilised coral platform, depth: 0.2–0.5 m, in burrows, suction pump, coll. A. Anker et al., 25.iii. 2015; 1 female (cl 7.1 mm), OUMNH.ZC. 2015 -08-025, Isla Grande, southwestern shore, 9.628281 - 79.565538, silt-mud bottom, depth: 1–1.5 m, in burrows, suction pump, coll. A. Anker et al., 27.iii. 2015. Additional material examined. Panama, Caribbean coast: 1 male (cl 3.9 mm), 1 female (cl 5.7 mm), UP, between Colón and Portobelo, 9.491252 -79.709096, shallow pools on sand flat exposed at low tide, fringed by sea grass, near fossilised coral platform, depth: 0.2–0.5 m, in burrows, suction pump, coll. A. Anker et al., 25.iii. 2015. Venezuela: 1 male (cl 9.2 mm), UDO-GIC 653, Sucre, off Barcelona, Isla Chimana Grande, La Cienaguita, 10.290833 -64.650278, sand-mud flat near mangrove, depth: 0.2–0.3 m, in burrows, suction pump, coll. J. Vera Caripe, 05.vi. 2010. Description. Carapace with frontal margin produced in broadly triangular rostral projection; pterygostomial angle rounded, not anteriorly produced; branchiostegial margin with pronounced lip; posterior margin with deep cardiac notch; carapace surface finely pitted (Fig. 1 a, b). Pleon with all pleomeres rounded; sixth pleomere with subtriangular, distally somewhat rounded articulated flap (Fig. 1 c). Telson relatively narrow, tapering distally; dorsal surface with two pairs of strong spiniform setae situated at some distance from lateral margin; posterior margin broadly rounded, about 0.7 length of proximal width of telson, each posterolateral angle with two pairs of spiniform setae, lateral much shorter than mesial; margin between mesial spiniform setae with numerous (12–14) long plumose setae (Fig. 1 d). Eyestalks with anteromesial margin rounded, protruding, with minute tubercle anterodorsally (indicated in Fig. 1 b). Antennular peduncles fairly stout, flattened dorsoventrally; stylocerite appressed against first article, with subacute point not reaching distal margin of first article; ventromesial carina of first article with simple, anteriorly pointing tooth; second article about twice as long as wide; lateral flagellum with short secondary ramus partly fused to main ramus, furnished with several tufts of aesthetascs (Fig. 1 a, b, e, f). Antenna with large basicerite ending in stout sharp distoventral tooth; scaphocerite oval, with small subacute distolateral tooth, latter not reaching beyond anterior margin of broad blade; carpocerite stout, reaching far beyond scaphocerite and slightly beyond end of antennular peduncle; flagellum robust (Fig. 1 a, b). Mouthparts (mandible, maxillule, maxilla, first and second maxillipeds) typical for genus in external view. Third maxilliped with lateral plate on coxa strongly projecting towards arthrobranch, distally subacute; ultimate article shorter than antepenultimate, with rings of thick serrulate setae and blunt tip, latter without spiniform setae (Fig. 1 g). Chelipeds very asymmetrical in shape and unequal in size, with smooth surfaces, both folded when not in use. Major cheliped slender proximally, but with relatively stout chela; ischium very short; merus slender, slightly twisted, ventrally depressed, ventromesial margin rugose, ending in small triangular tooth; carpus short, cupshaped; chela elongate, moderately swollen, with palm depressed ventrally, fingers about half palm length, twisted, slightly gaping when closed; cutting edge of pollex with one small proximal tooth, one large broad subtriangular tooth at about 0.4 length of pollex, one stout, distally truncate subdistal tooth perpendicular to pollex axis, and one smaller distal tooth adjacent to truncate pollex; cutting edge of dactylus with one large, distally truncate and minutely serrated tooth, situated at about 0.3 pollex length, one broad bulge occupying cutting edge between 0.3 and 0.8 pollex length, and one small subtriangular subdistal tooth, dactylus tip strongly curved, truncate (Fig. 2 a– e). Minor cheliped much smaller than major cheliped; ischium short; merus moderately slender, ventrally depressed, with smooth margins; carpus very short, cup-shaped; chela moderately inflated, flattened mesially, with fingers slightly longer than palm, with crossing tips; cutting edge of pollex with about 14 small, widely spaced teeth evenly distributed from pollex base to about 0.7 pollex length; cutting edge of dactylus with seven small, widely spaced teeth, distributed approximately between 0.3 and 0.7 dactylus length (Fig. 3 a–c). Second pereiopod slender, with merus distinctly longer than ischium; carpus five-articulated, with article ratio approximately equal to 5.0: 1.0: 1.5: 1.2: 3.4 (Fig. 3 d). Third pereiopod relatively stout, compressed; ischium without spiniform seta on ventrolateral surface; merus about four times as long as wide; carpus about 0.4 length of merus, with distoventral spiniform seta; propodus with two short spiniform setae on ventral margin and one pair of spiniform setae adjacent to dactylus; dactylus about half length of propodus, slender, conical, slightly curved, acute distally (Fig. 3 e). Fourth pereiopod generally similar to third pereiopod, merus more slender, close to five times as long as wide; carpus with much smaller distoventral spiniform seta; propodus with three short spiniform setae on ventral margin and one pair of spiniform setae adjacent to dactylus; dactylus about 0.4 length of propodus, moderately slender, conical, slightly curved, acute distally (Fig. 3 f). Fifth pereiopod distinctly more slender than third and fourth pereiopods, not compressed; carpus about 0.6 length of merus; propodus with well-developed grooming brush distolaterally, consisting of at least nine rows of serrulate setae, ventromesial margin with two short spiniform setae (invisible in lateral view); dactylus similar to that of fourth pereiopod (Fig. 3 g, h). Male second pleopod with slender appendix masculina significantly exceeding appendix interna, with stiff setae on apex and margin opposed to endopod margin (Fig. 1 h). Uropod with lateral lobe of protopod ending in two small, sharp, somewhat spaced teeth; exopod with distal margin truncate, forming conspicuous lateral angle; diaeresis with straight lateral portion, broad and deep mesial incision flanked by strong projecting tooth near mesial margin (Fig. 1 i). Gill-exopod formula typical for genus. Colouration. Body semitransparent pinkish, with numerous scattered red chromatophores, forming diffuse bands on the pleon; antennules and uropods sometimes brighter due to higher concentration of red chromatophores; major and minor chelae creamy white (Fig. 4); see also Anker 2011: fig. 19 A, B). Type locality. Bocas del Toro, Caribbean coast of Panama. Distribution. Southern Caribbean Sea: Panama (Bocas del Toro, Colón-Portobelo area, Isla Grande) and Venezuela (Isla Chimana Grande). Etymology. The species is named after our late friend and colleague, the Venezuelan carcinologist Dr. Guido Pereira (1951–2015). Ecology. The Panamanian specimens of Leptalpheus pereirai sp. nov. were collected from burrows in silty sand or sandy mud substrate, usually close to or within sea grass beds, sometimes close to mangroves, in the lower intertidal or at shallow subtidal depths (0.2–1.5 m). The callianassid ghost shrimp Glypturus acanthochirus Stimpson, 1866 was collected at all three Panamanian sites (Bocas del Toro, Mechi, and Isla Grande), although never together with L. pereirai sp. nov. The single Venezuelan specimen was collected in similar conditions, in a depth of 0.2–0.3 m, and only a few meters away from a mangrove, which are abundant on Isla Chimana Grande. The syntopic burrowing decapod fauna included the snapping shrimp Alpheus estuariensis Christoffersen, 1984, and three ghost and mud shrimps, viz. Glypturus acantochirus (Callianassidae) Upogebia cf. omissa Gomes Corrêa, 1968 (Upogebiidae), and Axianassa intermedia Schmitt, 1924 (Axianassidae). Therefore, G. acanthochirus, being present at all collection sites, may well represent the burrowing host of L. pereirai sp. nov. Remarks. Leptalpheus pereirai sp. nov. belongs to an informal group of species characterised by the presence of well-developed adhesive disks on the major chela. This group also includes the western Atlantic L. axianassae Dworschak & Coelho, 1999, the eastern Pacific L. canterakintzi Anker & Lazarus, 2015, L. azuero Anker, 2011, L. corderoae Salgado-Barragán, Ayon-Parente & Hendrickx, 2014, and the Indo-West Pacific L. pacificus Banner & Banner, 1974, L. denticulatus Anker & Marin, 2009, and L. dworschaki Anker & Marin, 2009 (Dworschak & Coelho 1999; Anker & Marin 2009; Anker 2011; Salgado-Barragán et al. 2014; Anker & Lazarus 2015). The new species can be easily separated from L. axianassae as well as its sister species L. canterakintzi by the bidentate tip of the pollex of the major chela; the presence of a stout proximal tooth on the cutting edge of the major chela dactylus; the absence of a conspicuously enlarged triangular tooth on the dactylus and pollex of the minor chela; the longer second article of the antennular peduncle (almost twice as long as wide in L. pereirai sp. nov. vs. 1.2–1.3 times as long as wide in L. axianassae and L. canterakintzi) (cf. Dworschak & Coelho 1999; Anker & Lazarus 2015). Leptalpheus pereirai sp. nov. differs from L. azuero by the much longer second article of the antennular peduncle (almost twice as long as wide in L. pereirai sp. nov. vs. as long as wide in L. azuero); the shorter, more appressed stylocerite, with the tip not exceeding the distal margin of the first article of the antennular peduncle (vs. exceeding this margin in L. azuero); and the absence of a spiniform seta on the ischia of the third and fourth pereiopods, which is present in L. azuero (cf. Anker 2011). It may be rather easily distinguished from L. corderoae, for instance, by the smooth ventral margin of the pollex and palm of the major chela, which is rugose or covered with tubercles in L. corderoae; and the absence of a conspicuously enlarged triangular tooth on the dactylus and pollex of the minor chela (cf. Salgado-Barragán et al. 2014). In addition, L. pereirai sp. nov. can be distinguished from L. axianassae, L. canterakintzi, L. azuero and L. corderoae by the tooth on the mesioventral carina of the first article of the antennular peduncle being simple and not having a protruding rounded lobe dorsally, as in the other four species (cf. Dworschak & Coelho 1999; Anker 2011; Salgado-Barragán et al. 2014; Anker & Lazarus 2015). Finally, L. pereirai sp. nov. can be separated from the three Indo-West Pacific species, viz. L. pacificus, L. denticulatus and L. dworschaki, by the frontal margin having a triangular rostral projection (rounded in the Indo-West Pacific species); the presence of a stout proximal tooth on the cutting edge of the major chela dactylus; and the slightly rugose mesial margin of the major cheliped merus; specifically from L. denticulatus also by the absence of a small tooth on the mesial angle of the diaeresis of the uropodal exopod; and specifically from L. dworschaki also by several obvious differences in the configuration of the armature of the major chela fingers (cf. Anker & Marin 2009).Published as part of Anker, Arthur & Caripe, Jonathan Vera, 2016, Leptalpheus pereirai sp. nov., a new alpheid shrimp from Panama and Venezuela (Decapoda: Caridea), pp. 185-191 in Zootaxa 4127 (1) on pages 186-190, DOI: 10.11646/zootaxa.4127.1.11, http://zenodo.org/record/26722