Leptalpheus Williams, 1965

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 : 3

Leptalpheus Williams, 1965

Leptalpheus Williams, 1965: 193 .

Emended diagnosis. Carapace glabrous, not setose; frontal margin without orbital teeth, rounded or with more or less developed median rostral projection; small orbital crests present or absent; anterolateral suture present; pterygostomial angle rounded; branchiostegial margin with narrow ventral lip; posterior margin with deep cardiac notch. Sixth abdominal somite with posteroventral articulated plate. Telson with two pairs of spiniform setae dorsally; posterior margin rounded, with two pairs of posterolateral spiniform setae; anal tubercles more or less developed. Eyes concealed in dorsal and lateral views; anteromesial margin bluntly projecting. Antennular peduncles sometimes flattened dorsoventrally; ventromesial carina of first article with strong tooth; stylocerite appressed or not, rarely exceeding distal margin of first article; second article varying from shorter to much longer than wide; lateral antennular flagellum with short secondary ramus. Antenna with basicerite bearing distoventral tooth; scaphocerite with distolateral tooth; carpocerite exceeding scaphocerite. Mouthparts not especially modified; mandible with two-articulated palp; first maxilliped with elongate palp and broad caridean lobe; second maxilliped with elongate epipod. Third maxilliped with lateral plate on coxa more or less produced dorsally; tip of ultimate article unarmed. First pereiopods (chelipeds) very unequal in size and asymmetrical in shape, carried flexed; major cheliped elongate, with enlarged, elongate chela; merus depressed ventrally, with margins smooth, rugose or furnished with tubercles; carpus short, more or less cup-shaped; palm ventromesially depressed, smooth or with row or fields of tubercles; fingers with variously shaped armature, without tooth-fossa system; adhesive discs present or absent. Second pereiopod with carpus composed of four or five articles. Third pereiopod and fourth pereiopods strongly compressed laterally; ischium with or without spiniform seta ventrolaterally; carpus with distoventral spiniform seta; propodus with spiniform setae on ventral margin; dactylus simple, conical. Fifth pereiopod not compressed, shorter and more slender than third and fourth pereiopods; propodus with at least three setal rows distolaterally. Male second pleopod with appendix masculina exceeding appendix interna; female second pleopod with appendix interna only. Uropod with lateral lobe of protopod bifid distally; exopod distally rounded or truncate; endopod sometimes produced into posterior filament; diaeresis with deep incision and large triangular tooth near mesial margin of exopod. Gill/exopod formula: 5 pleurobranchs (P1–5), 1 arthrobranch (Mxp3), 2 lobe-like epipods (Mxp1–2), 0 podobranchs, 5 mastigobranchs (Mxp3, P1–4), 5 setobranchs (P1–5), 3 exopods (Mxp1–3).

Species included. Leptalpheus forceps Williams, 1965 (type species), L. pacificus Banner & Banner, 1974 , L. mexicanus Ríos & Carvacho, 1983 , L. axianassae Dworschak & Coelho, 1999 (? = L. petronii Ramos-Porto & Souza, 1994 , nomen dubium, see Anker et al. 2006 for discussion), L. felderi Anker, Vera Caripe & Lira, 2006 , L. pierrenoeli Anker, 2008 , L. denticulatus Anker & Marin, 2009 , L. dworschaki Anker & Marin, 2009 , L. marginalis sp. nov., L. azuero sp. nov., L. penicillatus sp. nov., L. hendrickxi sp. nov., L. bicristatus sp. nov.

Distribution. Pantropical except for East Atlantic. Indo-West Pacific: Madagascar, Vietnam, Philippines, Fiji, French Polynesia, Hawaii. East Pacific: Mexico, Nicaragua, Costa Rica, Panama, Colombia. West Atlantic: southeastern USA (North Carolina, Florida, Louisiana), Venezuela, Aruba, Panama, Costa Rica, Brazil (Sergipe, São Paulo).

Remarks. The increasing morphological diversity of Leptalpheus , especially in the proportions of the antennular peduncles, the shape and length of the stylocerite, and the armature of the major chela fingers, calls for a phylogenetic investigation of this genus. It is possible that some morphologically and genetically well-defined clades will be assigned to new subgenera or even genera. However, in the absence of molecular data for many taxa and in the presence of further undescribed species ( Felder et al. 2003; Anker et al. 2006; see also below), a subdivision of Leptalpheus in either subgenera or genera is not possible at this time.