Synalpheus bocas, Anker, Arthur & Tóth, Eva, 2008

Anker, Arthur & Tóth, Eva, 2008, A preliminary revision of the Synalpheus paraneptunus Coutière, 1909 species complex (Crustacea: Decapoda: Alpheidae), Zootaxa 1915, pp. 1-28 : 17-18

Synalpheus bocas n. sp.

( Figs. 10 , 11 , 14 E–H)

Type material. Panama, Caribbean coast. Holotype, breeding female, USNM 1116687, Bocas del Boro, STRI Bay, in sponge Xestospongia rosariensis , 5–15 m, coll. E. Tóth, 3 Sep 2003 [03-033a]. Paratypes: 2 nonbreeding specimens USNM 1116688, same collection data as for holotype [03-032]; 1 non-breeding specimen, USNM 1116689, same collection data as for holotype [03-033b]; 1 male, USNM 1116690, same collection data as for holotype [03-039]; 2 males, 2 breeding females, USNM 1116691, same collection data as for holotype [03-040]; 1 male, 1 breeding female, UP, same collection data as for holotype [03-041]; 1 breding female, 1 male, USNM 1116692, Bocas del Toro, STRI Bay, 8–9 m, in sponge Xestospongia rosariensis , coll. E. Tóth, 15 Jan 2006 [06-714, one specimen dissected]; 1 breeding female, USNM 116693, Bocas del Toro, Isla Colón, Punta Caracol, 1–3 m, in sponges, coll. A. Anker, I. Marin and A. Baeza, 28 Apr 2007 [07-144b, photo voucher]; 1 non-breeding specimen, USNM 1116694, same collection data as previous specimen [07- 141b, photo voucher].

Diagnosis. Rostrum not lower than orbital hoods, rather broad at base, not particularly slender, subequal to orbital teeth, with subacute tip; orbital teeth triangular, broad at base, subacute; both rostrum and orbital teeth slightly up-turned distally; notches between orbital teeth and rostrum moderately deep, in-between V- and U-shaped. Antennular peduncles with second segment distinctly longer than wide; stylocerite overreaching distal margin of first segment. Antenna with basicerite bearing blunt, almost non-projecting distodorsal tooth; scaphocerite without blade. Third maxilliped with crown of eight-nine spine-like setae on tip of ultimate segment. Major chela with palm about 2.5 times as long as fingers; distodorsal tooth on palm not bulging, with anteriorly directed or slightly descendant acute point. Second pereiopod carpus with five segments, first carpal segment about four times length of second. Third pereiopod with propodus bearing eight spine-like setae (not including distal pair); dactylus stout. Uropodal exopod with two fixed teeth (including lateral tooth of diaeresis) and slender movable spine-like seta. Telson with longitudinal median depression and two pairs of very stout spine-like setae inserted anterior and posterior to mid-length, respectively; posterior margin broad, about half-length of anterior width, rounded (see Figs. 10 , 11 ). For detailed description of general features of S. paraneptunus species complex see Dardeau (1984) and Ríos & Duffy (2007).

Etymology. The new species’ name was derived from the first word of the type locality, Bocas del Toro, Panama; “ bocas ” (mouths in Spanish) was here used as noun in opposition.

Colour pattern. Whitish semitransparent, with reddish chromatophores distributed in diffuse bands over the entire body, more on abdomen; major chela pale beige, distal margin of palm and fingers pale brown (except for pale area surrounded by darker margin on dactylus), tips amber-yellow; ovaries or fresh brood green ( Fig. 14 E–H), exceptionally greenish yellow (one female from San Cristobal, Bocas del Toro).

Size. – Largest male, CL 4.9 mm; largest breeding female, CL 5.8 mm (holotype female, CL 5.7 mm).

Type locality. Bocas del Toro, Panama.

Distribution. Presently known only from Bocas del Toro, Panama.

Life history. This presumably pair-living species occurs in several sponges in Bocas del Toro. For instance, several sexual pairs of S. bocas n. sp. frequently inhabit Xestospongia rosariensis Zea and Rützler, 1983 ( Fig. 15 C, D), often together with congeners, such as the pair-living S. dardeaui ( Ríos and Duffy, 2007) and the eusocial S. rathbunae Coutière, 1909 . It also occurs in single sexual pairs in the sponge Xestospongia sp. ( Fig. 15 E), which superficially is intermediate between Xestospongia proxima (Duchassaing and Michelotti, 1864) and X. subtriangularis (Duchassaing, 1850) , and perhaps also in Calyx podatypa (E. Tóth, pers. obs.). The larvae of S. bocas n. sp. appear to be pelagic (E. Tóth, pers. obs.).

Remarks. Synalpheus bocas n. sp. differs from all previous species, viz. S. paraneptunus , S. duffyi n. sp., S. riosi n. sp., and S. brevidactylus n. sp. by the consistent absence of a blade on the antennal scaphocerite ( Fig. 10 A); the presence of only two teeth on the uropodal exopod ( Fig. 10 G); the rostrum being subequal in length to the orbital teeth ( Fig. 10 A); and the third maxilliped distally armed with a crown of eight or nine spine-like setae (vs. at most six in the other species) ( Fig. 10 C). In life, S. bocas n. sp. can be distinguished from S. duffyi n. sp. and S. brevidactylus n. sp. (the only two species with known colour patterns) by the presence of diffuse bands of reddish chromatophores on the abdomen and in some areas of the carapace. It also differs from S. duffyi n. sp. by its much larger size in adults (see Table 1 ).

Figures

FIGURE 10. Synalpheus bocas n. sp., paratype, male from Bocas del Toro, Panama (USNM 1116692): A, frontal region, dorsal view; B, same, lateral view; C, third maxilliped, tip of ultimate segment, lateral view; D, second pereiopod, lateral view; E, third pereiopod, lateral view; F, abdomen, lateral view; G, telson and uropods, dorsal view. Scale bar: 0.5 mm (A – E, G), 1 mm (F).

FIGURE 11. Synalpheus bocas n. sp., paratype, male from Bocas del Toro, Panama (USNM 1116692) [A – E]; paratype, male (USNM 1116690) [F]: A, major cheliped, lateral view; B, same, chela, mesial view; C, same, distal portion with opened fingers, lateral view; D, minor cheliped, lateral view; E, same, chela with opened fingers, mesial view, F, minor chela of young male with opened fingers, dorsolateral aspect. Scale bar: 0.5 mm (C – F), 1 mm (A, B).

FIGURE 14. Life habitus and colour patterns. Synalpheus duffyi n. sp., Isla Grande, Panama [A, B]: A, larger queen and two smaller non-breeding colony members from the same colony, dorsal view; B, queen with embryos, lateral view. Synalpheus brevidactylus n. sp., Isla Grande, Panama [C, D]: C, breeding female and male (mated pair), dorsal view; D, breeding female, lateral view. Synalpheus bocas n. sp., Bocas del Toro, Panama [E – H]: E, male, dorsal view; F, breeding female; G, H, another breeding female, lateral and dorsal views on different backgrounds. Synalpheus belizensis n. sp., Carrie Bow Cay, Belize [I]: I, breeding female, dorsal view. Scale bars: ~ 2 mm.

FIGURE 15. Sponge hosts of some species from the Synalpheus paraneptunus Coutière, 1909 species complex: A, several members of a colony of Synalpheus duffyi n. sp. in their host sponge, possibly Neopetrosia subtriangularis, Isla Grande, Panama; B, same, close-up of a non-breeding colony member; C, Xestospongia rosariensis, main host of Synalpheus bocas n. sp., Bocas del Toro, Panama; D, same, longitudinal section showing details of canals; E, Xestospongia sp., occasional host of S. bocas n. sp., Bocas del Toro, Panama. Scale bars: ~ 3 mm (A, B), ~ 5 cm (C – E).