Leptalpheus Williams, 1965

Anker, Arthur, Vera Caripe, Jonathan A. & Lira, Carlos, 2006, Description of a new species of commensal alpheid shrimp (Crustacea, Decapoda) from the southern Caribbean Sea, Zoosystema 28 (3), pp. 683-702 : 685-687

Genus Leptalpheus Williams, 1965

TYPE SPECIES. — Leptalpheus forceps Williams, 1965 .

SPECIES INCLUDED. — Leptalpheus forceps Williams, 1965 , L. pacificus Banner & Banner, 1974 , L. mexicanus Ríos & Carvacho, 1983 , L. axianassae Dworschak & Coelho, 1999 (synonym: L. petronii Ramos-Porto & Souza, 1994 ), L. felderi n. sp. (see below).

DISTRIBUTION. — Western Atlantic from North Carolina, USA, through Caribbean and Gulf of Mexico to São Paulo, Brazil; Eastern Pacific from Gulf of California to Colombia; Indo-West Pacific from Madagascar to Hawaii.

DIAGNOSIS. — Carapace glabrous, with more or less conspicuous longitudinal anterolateral suture; branchiostegial margin with pronounced lip. Frontal margin rounded, without rostrum, or with acute median rostral projection; orbital teeth absent; orbital hoods with or without small crests above eyes. Pterygostomial angle rounded. Eyes completely concealed in dorsal view, visible in frontal view, eyestalk with more or less developed rounded anteromesial process. Antennular peduncle slender to relatively stout; first segment with strong tooth on ventromesial carina; stylocerite more or less apressed to first segment; second segment sometimes elongated, much longer than visible portion of first; lateral antennular flagellum biramous, shorter ramus with at least two free segments. Antenna with basicerite robust; carpocerite exceeding scaphocerite; flagellum robust, compressed.Mandible with bisegmented palp; incisor process usually with five to seven triangular distal teeth, molar process with distal rows of setae and lamellae. First maxilliped with palp (endopod) elongated and caridean lobe greatly expanded. Second maxilliped with epipod elongated. Third maxilliped pediform; lateral plate conspicuously elongated, acute or subacute; ultimate segment with rows of long, distally thickened setae, tip unarmed. First pereiopods (chelipeds) enlarged, very unequal in size, asymmetrical in shape, carried flexed; major cheliped on left or right side (chelipeds antisymmetrical). Major cheliped slender, smooth or with small rugosities on ischium, merus and chela; ischium with or without tooth on ventromesial margin; merus slender, elongated, more or less flattened or shallowly excavated on ventral margin; carpus cup-shaped, sometimes ventrally depressed and with distal processes or lobes; palm with or without small tubercles or granules, with broad, shallow ventromesial groove, linea impressa absent; fingers often strongly curved or forceps-shaped, sometimes gaping, cutting edges usually armed with variously shaped teeth, snapping mechanism absent; dactylus with or without dense rows of filtering setae; adhesive discs present or absent. Second pereiopod with five- or four-segmented carpus. Third and fourth pereiopods compressed; third pereiopod with ischium unarmed or armed with one spine on ventral margin; carpus armed with spine on distoventral margin; propodus armed with three to five spines on ventral margin; dactylus simple, conical.

Anker A. et al.

TABLE 1. — Preliminary list of species of Leptalpheus Wiiliams, 1965 and Fenneralpheus Felder & Manning, 1986 . Abbreviations:

CAL, Thalassinidea, Callianassidae ; LAO, Thalassinidea, Laomediidae ; LYS, Stomatopoda , Lysiosquillidae ; UPO, Thalassinidea,

Upogebiidae .

Fifth pereiopod with propodus bearing well developed brush of setae. Sixth abdominal somite with articulated plate at posteroventral angle. Male second pleopod with appendix interna and appendix masculina. Uropod with posterior margin of exopod truncate; diaeresis with deep incision proximal to mesial margin of exopod; lateral spine strong. Telson with two pairs of dorsal spines and two pairs of posterolateral spines; posterior margin rounded; anal tubercles absent or poorly developed. Gill formula: five pleurobranchs (P1-5); one well developed

A new species of Alpheidae (Crustacea, Decapoda ) from the Caribbean Sea or hypertrophied arthrobranch (Mxp3); Mxp2 without podobranch; two lobed epipods (Mxp1-2); five strap-like epipods or mastigobranchs (Mxp3, P1-4); five sets of setobranchs (P1-5); three exopods (Mxp1-3).

REMARKS

The emended diagnosis of Leptalpheus includes features of all described and several undescribed species known to the senior author. In view of the increasing morphological heterogeneity of Leptalpheus s.l., several species may be subsequently assigned to other genera (D. Felder pers. comm.). In this case, the diagnosis of Leptalpheus s.s. will be restricted to the type species, L. forceps , and several closely related species. As a first step to the general revision of Leptalpheus s.l. and pending generic rearrangements, we define three morphologically distinctive species groups.