Leptalpheus hendrickxi, Anker, Arthur, 2011

Anker, Arthur, 2011, Six new species and three new records of infaunal alpheid shrimps from the genera Leptalpheus Williams, 1965 and Fenneralpheus Felder & Manning, 1986 (Crustacea, Decapoda), Zootaxa 3041, pp. 1-38 : 15-19

Leptalpheus hendrickxi sp. nov.

Figs. 11–14

Type material. Holotype: female (cl 6.0 mm), MNHN-IU-2011-5242, Panama, Pacific coast, Chitré, Playa El Aguillito, mudflat near mangroves, yabby pump, 0.2–0.5 m at low tide, leg. A. Anker, J.A. Vera Caripe, 0 8.11.2006 [fcn 06-532]. Paratypes: 1 male (cl 5.3 mm), RMNH D54561, same collection data [fcn 06-527]; 1 male (cl 4.5 mm), OUMNH.ZC. 2011-06-021, same collection data [fcn 06-530].

Description. Frontal margin of carapace produced into broadly triangular rostral projection, latter somewhat descendent in lateral view, without orbital crests ( Fig. 11 A, B). Telson widest in proximal third, ovate, slightly tapering distally; dorsal surface with two pairs of strong spiniform setae inserted in deep pits at some distance from lateral margin; posterior margin broadly rounded, with two pairs of spiniform setae at posterolateral angles, lateral much more slender and shorter than mesial ( Fig. 11 C).

Eyestalks with anteromesial margin rounded, slightly projecting ( Fig. 11 A). Antennular peduncles moderately stout, somewhat flattened dorsoventrally; stylocerite appressed, not exceeding distal margin of first article; ventromesial carina with strong tooth ending in acute point and large, subtriangular, blunt tooth, latter reaching slightly beyond acute point; second article about 1.5 times longer than wide; lateral flagellum with relatively long secondary ramus ( Fig. 11 A, B, D). Antenna with basicerite moderately stout, with distoventral tooth; scaphocerite ovate, with small distolateral tooth not reaching beyond anterior margin of blade; carpocerite stout, reaching somewhat beyond scaphocerite and end of antennular peduncle ( Fig. 11 B, E). Mouthparts typical for genus, as illustrated ( Fig. 12 A–E). Third maxilliped with moderatley elongate, distally subacute lateral plate on coxa ( Fig. 12 G).

Major cheliped elongate, relatively slender; ischium without mesial process; merus moderately slender, depressed ventrally, mesial and lateral margins with row of widely spaced, strong, subtriangular or rounded teeth, along entire margin, some distal teeth bifid; dorsal surface with field of blunt teeth around its mid-length; carpus cup-shaped, smooth, with dorsal constriction; chela relatively slender, elongate, with palm depressed ventrally; ventromesial and ventrolateral margins of palm with rows of more or less spaced, strong, subtriangular teeth, ventromesial row extending from pollex tip to palm base, ventrolateral row extending from pollex base to palm base; additional row of teeth present on mesial surface, extending from base of pollex to about mid-length of palm; fingers less than 0.4 length of palm, somewhat twisted and curved, not gaping when closed; cutting edge of dactylus armed with large, distally rugose tooth; cutting edge of pollex armed with two large teeth, proximal larger and rugose distally, subdistal slightly bent backwards, blunt; adhesive disks absent ( Fig. 13 ). Minor cheliped with ischium unarmed; merus relatively stout, ventrally depressed, ventromesial margin with row of strong, subtriangular teeth; carpus short, cup-shaped; chela moderately slender, simple, with fingers about 0.8 length of palm, tips crossing distally; cutting edge of dactylus and pollex armed with small, widely spaced teeth, as illustrated ( Fig. 11 F, G).

Second pereiopod with merus distinctly shorter than carpus; carpus five-articulated, with article ratio approximately equal to 4.5: 1: 1: 1: 2 ( Fig. 11 H). Third and fourth pereiopods similar; third pereiopod relatively stout, compressed; ischium unarmed; merus about 4.5 times as long as wide; carpus less than 0.4 length of merus, with distoventral spiniform seta; propodus with three slender spiniform setae along ventral margin; dactylus slightly more than half length of propodus, conical, slender, acute distally ( Fig. 11 I). Fifth pereiopod slender, not compressed; propodus with five setal rows distolaterally ( Fig. 11 J).

Male second pleopod with slender appendix masculina, latter almost double length of appendix interna, with three stiff setae on apex ( Fig. 11 K). Uropod with lateral lobe of protopod ending in two small, adjacent teeth; exopod with truncate margin; diaeresis with lateral portion straight, with deep mesial incision and large tooth at mesial margin ( Fig. 11 L).

Size. The type specimens range from 4.5 to 6.0 mm cl.

Colour in life. Semitransparent with numerous red chromatophores, some arranged in transverse bands on the abdomen; antennular and antennal peduncles and tail fan also with red chromatophores; cheliped merus and carpus reddish, chelae hyaline-white; walking legs semitransparent ( Fig. 14 ).

Etymology. It is a great pleasure for the author to name this interesting alpheid shrimp after Dr. Michel E. Hendrickx (Instituto de Ciencias del Mar y Limnología, UNAM-Mazatlán, Mexico), in recognition of his numerous contributions to the taxonomy, biogeography and ecology of eastern Pacific decapods.

Type locality. Panama, Pacific coast, Playa El Aguillito near Chitré.

Distribution. Eastern Pacific: presently known only from the type locality on the Azuero Peninsula of Panama.

Ecology. Shallow sand-mud flat near mangroves, in burrows of unknown hosts; Leptalpheus azuero sp. nov. and several species of Lepidophthalmus , Upogebia and Axianassa were also collected at this site (A. Anker, pers. obs.; Dworschak & Anker, in study).

Remarks. Leptalpheus hendrickxi sp. nov. is unique among species of Leptalpheus in the configuration of both the minor and the major chelipeds ( Figs. 11 F, G, 13). No other species of Leptalpheus has strong teeth on the mesial (or any other) margin of the merus of the minor cheliped ( Fig. 11 F). The row of very strong teeth, some of them bifid, on the merus of the major cheliped ( Fig. 13 C), as well as on the ventral side of the major chela ( Fig. 13 D, E), are also diagnostic of this species. The armature of the major chela fingers of L. hendrickxi sp. nov. shows some similarities to that of L. azuero sp. nov. (see above) and the three species of the L. pacificus complex ( Anker & Marin 2009), but the teeth are different in both shape and position; in addition, the dactylar tooth and the proximal tooth on the pollex are somewhat rugose distally ( Fig. 13 E), which is not the case in the other species.

Figures

FIGURE 11. Leptalpheus hendrickxi sp. nov., paratype, male from Playa El Aguillito, Azuero Peninsula, Pacific coast of Panama (RMNH D 54561): A, frontal region, dorsal view; B, same, lateral view; C, telson, dorsal view; D, ventromesial tooth on first article of antennular peduncle, lateral view; E, scaphocerite, dorsal view; F, minor cheliped, lateral view; G, same, carpus and chela, mesial view; H, second pereiopod, lateral view; I, third pereiopod, lateral view; J, fifth pereiopod, lateral view; K, appendix masculina and appendix interna, dorsal view; L, uropod, dorsal view (setae omitted).

FIGURE 12. Leptalpheus hendrickxi sp. nov., paratype, male from Playa El Aguillito, Azuero Peninsula, Pacific coast of Panama (RMNH D 54561): A, mandible, mesial view; B, maxillule, lateral view; C, maxilla, lateral view; D, first maxilliped, lateral view; E, second maxilliped, lateral view; F, same, endopod, mesial view; G, third maxilliped, lateral view.

FIGURE 13. Leptalpheus hendrickxi sp. nov., paratype, male from Playa El Aguillito, Azuero Peninsula, Pacific coast of Panama (RMNH D 54561): A, major cheliped, lateral view; B, same, mesial view; C, same, merus, mesial view; D, same, carpus and chela, mesial view; E, major chela fingers, lateral view.

FIGURE 14. Leptalpheus hendrickxi sp. nov., holotype, female from Playa El Aguillito, Azuero Peninsula, Pacific coast of Panama (MNHN-IU- 2011 - 5242): A, lateral view; B, dorsal view.