Zuzalpheus pectiniger ( Coutière, 1907 ) Ríos, Rubén & Duffy, J. Emmett, 2007

Ríos, Rubén & Duffy, J. Emmett, 2007, A review of the sponge‑dwelling snapping shrimp from Carrie Bow Cay, Belize, with description of Zuzalpheus, new genus, and six new species (Crustacea: Decapoda: Alpheidae), Zootaxa 1602 (1), pp. 1-89 : 57-58

Zuzalpheus pectiniger ( Coutière, 1907) n. comb.

( Plate 4 )

Synalpheus pectiniger Coutière, 1907:611 ; Coutière, 1909:78–82, fig. 48; Dardeau:98–102, figs. 51–53 (and synonymy).

Material examined. (1) 14 ♂, 4.3–4.4 mm, 6 ovigerous ♀, 3.9–5.3 mm ( VIMS 93 CBC2902), Twin Cays , Belize, 22 March 1993, in Spheciospongia vesparium , 1.5 m .

(2) 1 ovigerous ♀ ( VIMS 93 CBC2012), 4.0 mm, 1 ♂ ( VIMS 93 CBC2013), 4.2 mm, Blue Ground Range , W of Carrie Bow Cay, Belize, 19 March 1993, in Spheciospongia vesparium , 1.5 m .

(3) 3 ♂ ( VIMS93 CBC2102, 93CBC2113, 93CBC2114), 2.9 mm, 4.0 mm, 4.1 mm, Blue Ground Range , Belize, 19 March 1993, in Spheciospongia vesparium , 1.5 m .

(4) 4 ovigerous ♀ ( VIMS 93 CBC2605, 93CBC2609, 93CBC2610, 93CBC2611), 4.6 mm, 4.6 mm, 4.8 mm, 4.6 mm, 4 ♂ ( VIMS 93 CBC2603, 93CBC2606, 93CBC2607, 93CBC2608), 4.2 mm, 5.0 mm, 3.7 mm, 4.1 mm, Twin Cays , Belize, 21 March 1993, in Spheciospongia vesparium , 1.5 m .

(5) 1 ♂ ( VIMS 95 F4107), 4.3 mm, Three Sisters Reef , Florida Keys, USA, 19 May 1995, in Spheciospongia vesparium , 4.2 m .

Diagnosis. Body subcylindrical; carapace smooth, glabrous, with pterygostomian corner broadly obtuse, and posterior margin with cardiac notch diminished. Rostrum carinate, about as long as, but slightly narrower than, orbital hoods, distally upturned; margins in dorsal view convex. Orbitorostral process absent. Ocular hoods dorsally convex; in dorsal view acute, separated from rostrum by deep circular adrostral sinus. Ocular process broad. Ocellary beak in lateral view broad at base, not rod-like. Stylocerite slender, tip acute, reaching about as far as distal margin of first antennular peduncle; this latter segment without mesio-ventral tooth, and with 2 basal ventral processes. Basicerite without spine on dorso-lateral corner, and with ventrolateral spine reaching distal half of second segment of antennular peduncle. Scaphocerite without blade; mesial projection at base of scaphocerite present. Maxilliped 3 with distal circlet of spines on distal segment, and without ventro-distal spine on antepenultimate segment.

Major pereopod 1 massive, fingers shorter than half length of palm; fixed finger reduced to less than half length of dactyl; in ventral view, fixed finger widely triangular, almost rounded distally and without any obvious protuberance on outer face. Palm of chela with distal superior margin produced into acute conical projection, somewhat flattened dorsoventrally, overhanging base of dactyl. Merus extensor margin slightly convex with flat distal angular projection.

Minor pereopod 1 with palm less than twice as long as high; fingers clearly shorter than palm; dactyl with flexor margin straight, blade-like, with 3 strong distal teeth, equal in length, and parallel to dactyl axis; transverse dorsal setal combs on extensor surface of dactyl very conspicuous; fixed finger with flexor margin straight, blade-like, with 2 strong teeth subequal in length, and adjacent bump; merus with extensor margin slightly convex with flat distal angular projection.

Pereopod 2 with carpus 5-segmented, slightly longer than merus.

Pereopod 3 slender; dactyl biunguiculate, with flexor tooth slightly thicker than terminal tooth; merus without movable spines on flexor margin; mesial lamella on coxa present. Pereopods 4 and 5 normal.

Pleura 1 with dorsal anterior margin produced into distinct convex lobe; pleura of male usually strongly acuminate, sixth with 2 distinct spines; ovigerous females with pleura broadly rounded. Pleopod 1 of male, endopod with six terminal setae and four near base; pleopod 2 of male with marginal setae on exopod originating at base; appendix interna on second to fifth pleopods, present. Telson with space between posterior marginal spines less than one third width of posterior margin; marginal convex lobe absent. Anal flaps, perianal setae, and postanal setal brush all absent. Uropods with outer margin of exopod having 1–3 fixed teeth distinctly removed from mobile spine, and usually without adjacent inner fixed tooth.

Color ( Plate 4 ). Transparent with a distinctly pink facial region, due to expanded chromatophores, juxtaposed with the black stomach. Distal palm and fingers of major chela with brownish to blue-black tinge. Digestive gland dark olive, ovaries and embryos pale golden yellow.

Variations. Putative males (i. e., non ovigerous specimens) show abdominal pleurae with various degrees of elongation, in the extreme case resembling needle-like projections, in other cases with the tip strongly hooked anteriorly. Interestingly, the first pleura, which is typically considered the diagnostic secondary sexual character in most species of Synalpheus , frequently remains broadly rounded in putative male Z. pectiniger even when the posterior ones are acutely pointed. In most specimens both pairs of spines on the dorsal surface of the telson are located on the anterior half, but specimens with the posterior pair implanted slightly beyond the midlength of telson are not rare.

Hosts and ecology. Zuzalpheus pectiniger is evidently a strict host specialist in the loggerhead sponge Spheciospongia vesparium , in which it is a characteristic inhabitant throughout its geographic range. We know of no reliable records from any other host or habitat. It can be found in groups of up to a few hundred individuals, generally with approximately equal sex ratio in the larger size classes.

Distribution. Western Atlantic: Florida Keys, USA ( Coutière 1909; Duffy 1993); Bahamas ( Coutière 1909; Lemaitre 1984); Cuba (Martínez Iglesias and García Raso 1999); Virgin Islands ( Coutière 1909; Chace 1972); Gulf of Mexico ( Coutière 1909; Wass 1955; Tabb and Manning 1961; Rouse 1970; Lyons et al. 1971; Menzel 1971; Dardeau 1984; Erdmann and Blake 1987); Yucatan peninsula, Mexico ( Chace 1972); Belize Barrier Reef (this study); San Blas Islands, Panama ( Duffy 1992); Windward Islands ( Chace 1972); Netherlands Antilles ( Coutière 1907, 1909; Westinga and Hoetjes 1981).

Remarks. Identification of Z. pectiniger is relatively straightforward when specimens in good condition are available, as the tridentate dactyl of the minor chela is unique among West Atlantic Zuzalpheus . The large chela is also a reliable taxonomic character because of both the short fixed finger and the slanted conical projection overhanging the base of the dactyl.

Figures

PLATE 4. Zuzalpheus pandionis, female (VIMS 03CBC1701) from Lissodendoryx sp., Carrie Bow Cay, Belize. Zuzalpheus paraneptunus, female (VIMS 01CBC0704) from Oceanapia sp., Curlew Reef, Belize. Zuzalpheus pectiniger, female (VIMS 05FK1501) from Spheciospongia vesparium, Key Largo, Florida, USA. Zuzalpheus pectiniger, male (VIMS 05FK1502) from Spheciospongia vesparium, Key Largo, Florida, USA. Zuzalpheus regalis, female (VIMS 01CBC02) from Xestospongia cf. subtriangularis, Curlew Reef, Belize. Zuzalpheus ruetzleri, female (VIMS 01CBC6301) from Hymeniacidon caerulea, Sand Bores, Belize.