Revision of the western Atlantic members of the Alpheus armillatus H. Milne Edwards, 1837 species complex (Decapoda, Alpheidae), with description of seven new species Author Anker, Arthur text Zootaxa 2012 2012-07-12 3386 1 1 109 http://dx.doi.org/10.11646/zootaxa.3386.1.1 journal article 10.11646/zootaxa.3386.1.1 1175­5334 10096368 Alpheus nuno sp. nov. ( Figures 57–59 , 64J , 65K , 66K , 67I ) Type material . Mexico : holotype : female (cl 6.6), UNAM-CNCR 26485, Quintana Roo , Isla Cozumel , west coast, 1 km north of Playa Corona , off rugged shore platform (fossilised coral), hard flat bottom, under rocks next to wall, 2–3 m , leg. A. Anker , 08.07.2010 [fcn COZ5-009 , dissected] ; paratype : female (cl 4.8), OUMNH . ZC . 2011-06- 040, same collection data as for the holotype [fcn COZ5-010 ] . Diagnosis . Rostrum straight, exceeding half-length of first article of antennular peduncle; area posterior to rostral carina flattened, abruptly delimited from adjacent, relatively deep rostro-orbital furrows, forming V-shaped post-rostral plate continuous with very narrow, almost blade-like rostral carina, margins of post-rostral plate slightly overhanging rostro-orbital furrows; post-rostral plate situated slightly above and gently sloping into rostral carina. Antennule with stylocerite acute distally, reaching distal margin of first article; ventromesial carina of first article with tooth bearing subacute point above concave anterior margin; second article about 1.5 times as long as wide. Antenna with basicerite armed with stout, sharp distolateral tooth; scaphocerite with slightly concave lateral margin, strong distolateral tooth reaching beyond moderately broad blade; carpocerite exceeding scaphocerite blade and (very slightly) distolateral tooth, reaching slightly past end of antennular peduncles. Third maxilliped with ultimate article as broad as penultimate, tapering distally. Major cheliped edwardsii - type (see under A. armillatus ). Female cheliped with merus relatively stout, distodorsal margin blunt, ventromesial margin slightly rugose, without spiniform setae, with strong, sharp distomesial tooth; palm with dorsal shoulder rounded, sloping almost vertically into adjacent transverse groove, not overhanging groove; ventral shoulder broadly rounded, not projecting, with small field of minute tubercles laterally; fingers about half-length of palm; pollex without ridge mesially; dactylus plunger moderately large, distally truncate, proximal height about 0.8 length of distolateral margin, anterior angle more than 90°. Female minor cheliped with merus relatively slender, distodorsal margin blunt, ventromesial margin slightly rugose, without spiniform setae, distomesial tooth strong; chela slender, palm with lengthheight ratio about 2.5; palm without longitudinal depressions, with very slight ventral sinus, without distinct ventral shoulder; fingers about as long as palm, slender, simple, non-balaeniceps, with sharp cutting edges. Male major and male minor chelipeds unknown. Second pereiopod slender, with first two carpal articles longest, first about 1.3 length of second. Third and fourth pereiopods similar, rather slender; ischium with stout spiniform seta ventrolaterally; merus about five times as long as wide; propodus with stout spiniform setae, sometimes inserted in pairs, along ventral margin, incuding one pair adjacent to dactylus; dactylus at least 0.4 length of propodus, simple, conical. Fifth pereiopod more slender than third and fourth; ischium armed with stout spiniform seta in females. Sternum at the base of fourth pereiopods without conspicuously projecting, slender, subacute processes. First and second abdominal sternites with short, blunt median process in females. First to fourth pleopods of females without spiniform setae on ventrolateral margin of protopod. Uropod with exopod and endopod broadly rounded; exopod with sinuous diaeresis and stout distolateral spiniform seta; endopod with row of small spiniform setae on distal margin. Telson broad, slightly tapering posteriorly; dorsal surface with two pairs of spiniform setae inserted far from lateral margins; posterior margin broadly rounded, with row of small spiniform setae; posterolateral angles each with two slender spiniform setae, mesial much longer than lateral ( Figs. 57 , 58 ). Size range . The type specimens, both females, have a cl of 4.8 mm cl and 6.6 mm cl ( holotype ). Colour pattern . Body with bright red to red-brown chromatophores grouped into broad transverse bands, two on the carapace and one on each abdominal somite; post-rostral plate deep-red on margins; antennular and antennal flagella pale yellow with diffuse pale orange bands; chelipeds with ischium, merus and carpus whitish, distally with patches of red chromatophores; mesial face of major chela red-orange with pale or whitish patches and spots, including some on dactylus; distal portion of dactylus and pollex hyaline-white; mesial face of minor chela reddish, with some spots on palm, fingers mostly red with whitish tips; second to fifth pereiopods reddish with some colourless areas, for instance, near articulations; telson and uropods red ( Fig. 59 ). Etymology . Derived from the first name of Dr. Nuno Simões (UNAM, Sisal, Mexico ), for his shrimp-related enthusiasm and interest in alpheid taxonomy, which resulted in the collection of the type specimens during the author’s short field trip in July 2010 ; used as a noun in apposition. Type locality . Caribbean coast of Mexico : west coast of Cozumel . FIGURE 57 . Alpheus nuno sp. nov. : holotype, female from Cozumel, Mexico [UNAM-CNCR 26485]; A, frontal region of carapace and frontal appendages, dorsal view; B, rostro-orbital region of carapace, lateral view; C, same, dorsolateral view; D, tooth on mesioventral carina of first article of antennular peduncle, lateral view; E, antennal scaphocerite, dorsal view; F, second pereiopod, lateral view; G, third pereiopod, lateral view; H, same, distal propodus and dactylus, mesial view; I, fourth pereiopod, propodus and dactylus, FIGURE 58 . Alpheus nuno sp. nov. : holotype, female from Cozumel, Mexico [UNAM-CNCR 26485]; A major chela, mesial view; B, same, lateral view; C, same, detail of ventral shoulder, lateral view; D, same, detail of dorsal shoulder; lateral view; E, major chela dactylus, lateral view; F, major cheliped, ischium, merus and carpus, mesial view; G, minor cheliped, mesial view; H, minor chela, lateral view. Scale bars as indicated. Distribution . Western Caribbean Sea: presently known only from the type locality in Cozumel, Mexico (see map in Fig. 70 ). Ecology . Shallow subtidal reef flats; known depth range 2–3 m ; on mixed sand-rock bottom adjacent to fossilised coral platform; under coral rocks, some covered with a mat of green filamentous algae. Remarks . Alpheus nuno sp. nov. was collected one year after the publication of the molecular phylogeny of the A. armillatus complex ( Mathews & Anker 2009 ) and no molecular data is presently available for this species. In addition, both available specimens of A. nuno sp. nov. are females, which makes morphological comparisons with other species somewhat more complicated. However, A. nuno sp. nov. can be distinguished from all other species of the A. armillatus complex by the distinctly shorter second article of the antennular peduncle, which is about 1.5 times as long as wide vs. 2.0–2.5 times in the other species ( Figs. 57A , 65 ; see also Table 1). In addition, the unique and striking colour pattern of A. nuno sp. nov. ( Fig. 59 ), separate this species from any other species of the A. armillatus complex present in the western Atlantic. The confuguration of the post-rostral region of A. nuno sp. nov. is generally similar to those of A. amarillo sp. nov. , A. punctatus sp. nov. , and A. tampensis sp. nov. , although in A. nuno sp. nov. , the lateral margins of the plate are only slightly overhanging the orbito-rostral furrows, not forming a deep channel as in the other species. In addition, the rostral carina of A. nuno sp. nov. is much narrower than in the other three species (cf. Figs. 27A , 33A , 38A , 57A ). The female minor chela is relatively slender, approaching the proportions found in A. amarillo sp. nov. and to a lesser degree A. punctatus sp. nov. (cf. Figs. 28A , 34A , 58A ; see also Fig. 64 ). Based on these features A. nuno sp. nov. appears to be within or at least very close to Clade 1 of Mathews & Anker (2009) ; this, however, needs to be confirmed genetically. GenBank accession numbers . Presently unavailable.