Zuzalpheus regalis (Duffy, 1996) 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 : 58-61

Zuzalpheus regalis (Duffy, 1996) n. comb.

( Fig. 26 , Plate 4 )

Synalpheus regalis Duffy 1996b: 564 , fig. 1–5; Ríos 2003:136, figure 2–25, plate IV.

Material examined. ( 1) Holotype ♂ ( USNM 280092 ), 2.4 mm (rostrum excluded), from a colony of 89 ♂

( USNM 280093, 280095) and a single ovigerous ♀ ( USNM 280094 ) , Carrie Bow Cay , Belize, 28 March 1993, in Xestospongia cf. subtriangularis ( Duchassaing 1850) , 15 m.

(2) 13 individuals, 2.6–3.3 mm ( VIMS 01 CBC4803), and a single ovigerous ♀ ( VIMS 01 CBC4806) from a colony of 258, outer ridge at Curlew reef, Belize, 1 May 2001, inside sponge Xestospongia cf. subtriangularis , 15 m.

(3) 1 ovigerous ♀ ( VIMS 96 CBC3401), 2.7 mm, 60 ♂ ( VIMS 96 CBC3402), 1.3–2.9 mm, outer ridge at Carrie Bow Cay , Belize, 17 June 1996, in Xestospongia cf. subtriangularis , 15 m.

(4) 1 ovigerous ♀ ( VIMS 01 CBC4303), 3.9 mm, from a colony of 1 ovigerous ♀ and 204 others, outer ridge at Curlew reef, Belize, 1 May 2001, in Hyattella intestinalis , 15–20 m.

(5) 6 individuals, 2.4–2.7 mm ( VIMS 04 CBC0904), and a single ovigerous ♀ ( VIMS 04 CBC0905) , 3.2 mm, from a colony of 1 ovigerous ♀ and 71 others, outer ridge at Curlew reef, Belize, 12 March 2004, in Hyattella intestinalis , 15–20 m.

(6) 10 individuals, 2.6–3.0 mm ( VIMS 05 CBC0902, 05CBC0903), and a single ovigerous ♀ ( VIMS 04 CBC0905) , 3.9 mm, from a colony of 1 ovigerous ♀ and 101 others, outer ridge at Long reef, Belize, 10 July 2005, in Hyattella intestinalis , 20–25 m.

Diagnosis. Body subcylindrical; carapace smooth, sparsely setose, with pterygostomian corner very obtusely angular, and posterior margin with cardiac notch distinct. Rostrum lanceolate, about as long as, but much narrower than, ocular hoods, and distally upturned. Orbitorostral process absent. Ocular hoods dorsally convex; in dorsal view, bluntly rounded, margins convex, separated from rostrum by deep adrostral sinus. Ocular processes virtually absent, just a slightly swollen obtuse protuberance. Ocellary beak in lateral view not rod-like. Stylocerite thick, mesial margin slightly concave, tip acute, distinctly shorter than distal margin of first segment of antennular peduncle; this latter segment without ventromesial tooth, and with 2 basal ventral processes. Basicerite with strong sharp spine on dorsal margin, and with longer ventrolateral spine reaching about half length of second segment of antennular peduncle. Scaphocerite blade absent, acute lateral spine robust, with lateral margin slightly concave, normally not reaching distal margin of antennular peduncle; mesial corner at base of scaphocerite, obtuse. Maxilliped 3 with distal circlet of spines on distal segment, and without ventrodistal spine on antepenultimate segment

Major pereopod 1 massive, fingers shorter than half length of palm; fixed finger slightly shorter than dactyl; in ventral view, outer face of fixed finger with subtly obtuse protuberance. Palm of chela with distal superior margin produced into prominent rounded tubercle, occasionally with accessory acute spine on distoventral face. Merus, extensor margin strongly convex, ending in obtuse angle.

Minor pereopod 1 with palm less than 2 times longer than high; fingers clearly shorter than palm; dactyl simple, with flexor surface obliquely concave; transverse dorsal setal combs on extensor surface of dactyl very conspicuous; fixed finger with flexor surface obliquely concave, and no hint of second tooth. Extensor margin of merus convex, ending in obtuse angle.

Pereopod 2 with carpus 4-segmented, about as long as merus.

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

Pleura 1 of male with anterior corner prolonged into acute angle, and posterior corner acutely produced ventrally; pleura 2–5 of male produced into acute angle. Pleopod 1 of male, with 3 or 4 setae on endopod; second pleopod of male with marginal setae on exopod originating near midpoint; appendix interna on second to fifth male pleopods, present. Telson, space between distal spines about one-third of distal margin; marginal convex lobe, absent; posterior corners adjacent to spines, obtuse. Anal flaps, perianal setae, and postanal setal brush absent. Uropods with 2 to 4 fixed teeth on outer margin of exopod, usually removed from longer mobile spine.

Color ( Plate 4 ). Translucent orange with sparse red chromatophores in anteriodorsal part of carapace; distal palm and fingers of major chela bright orange to brown orange; ovaries and developing embryos pale green ( Duffy 1996c).

First larva. In the laboratory, three larvae were obtained from a wild-caught ovigerous female. The larvae were crawling megalopae very similar to those of Z. elizabethae , n. sp., but at an earlier stage. The pleopods are biramous, but unlike the ones in S elizabethae , n. sp., they do not have any setae. Also, the telson is less rectangular and has only the two pairs of setae on the distal margin, without any spines.

Variations. The anterior corner of the male first pleura normally has a ventrally oriented acute angle; relatively few of the specimens examined here had a broadly rounded corner as the one illustrated from the holotype ( Duffy 1996b), and this condition usually is associated with probable feminization due to abdominal parasitic isopods. The lateral spine of the scaphocerite seems to grow allometrically, it usually does not reach the distal edge of the antennular peduncle, but in the larger specimens it does reach that edge and occasionally it surpasses it sligthly. The number of fixed teeth on the lateral edge of the uropodal exopod varies from 1 in the smallest specimens up to 4 or 5 in the rare largest ones, but the most frequent numbers are 3, 2, and 4. Some of the intraspecific variability seems to be associated with particular colonies ( Duffy 1996c).

Hosts and ecology. We have found Zuzalpheus regalis almost exclusively within Xestospongia cf. subtriangularis and Hyattella intestinalis . On a few occasions we have collected this shrimp from Lissodendoryx cf. strongylata and Hymeniacidon caerulea . Eusocial colonies in a marine animal were first described in Z. regalis : dense populations (up to 300 individuals) of this species have a single reproductive female, distinct cohorts from a single colony are genetically related, and a certain degree of labor division has been described ( Duffy 1996a; Duffy et al. 2002).

Distribution. Western Atlantic: known only from the vicinity of the type locality at Carrie Bow, Belize.

Remarks. There are three additional species in the western Atlantic that are similar to Z. regalis . These are Zuzalpheus elizabethae , n. sp., Z. rathbunae , and Z. filidigitus . These small shrimp are genetically distinct ( Duffy1996c) and can be separated by several morphological characters ( Table 2). The ventral projections on the abdominal pleura in Z. regalis are more rounded than those of Z. rathbunae and Z. elizabethae , n. sp. The second chela has thicker fingers in Z. elizabethae , n. sp. and lastly, Z. rathbunae has an acute projection over the base of the dactyl of the major chela, instead of the more rounded protuberance of the other two species.

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.

FIGURE 26. Zuzalpheus regalis (Duffy 1996). Male 2.5 mm (VIMS 93CBC4802): a, abdomen, lateral view. Zuzalpheus rathbunae (Coutière 1909). Male 2.4 mm (VIMS 88SB12503):b, abdomen, lateral view. Scale bar = 1 mm.