Pontonides unciger Calman, 1939

Marin, Ivan, 2007, The coral-associated shrimp genus Pontonides (Caridea, Palaemonidae, Pontoniinae) in Nhatrang Bay, Vietnam, with description of two new species, Zootaxa 1635, pp. 1-21 : 15-17

Pontonides unciger Calman, 1939

( Figs. 9 , 10 C)

Pontonides unciger Calman, 1939: 213 , figs. 6, 7.

Pontonides unciger .— Bruce, 1976b: 284.— Monod, 1979: 10, figs. 9–35.—Li, 2000: 256.— Bruce, 2005: 376.

Material examined. Vietnam, Nhatrang Bay: 1 ovig. female (pcl. 1.5 mm), 1 male (pcl. 1.1 mm), Dun Island, 40–45 m depth, on Rhipidipathes sp., coll. I. Marin, 15 May 2006, ZMMU Ma 5490.

Diagnosis. Small-sized pontoniine shrimps with subcylindrical body. Carapace smooth, not gibbous. Rostrum long, not reaching mid-length of intermediate antennular segment. Supraorbital margin well developed, subrectangular, with small tooth; orbits well developed. Eyestalk without dorsal tubercle. Fourth pleura rounded; pleura of fifth abdominal segment posteroventrally produced and pointed. Second maxilliped with 4–5 fusiform setae on ischial segment. Third maxilliped with numerous fusiform setae along fused proximal basal segment. First to fifth pereiopods without fusiform setae on ischia. Second pereiopods subequal, differing slightly in shape of chela; major chela with palm undulate, very setose, with long simple setae along ventral and ventrolateral margins and shorter simple setae along dorsal margin; fingers stout, curved; minor chela setose, with long simple setae; fingers four times as long as wide, with curved tips. Third pereiopods smooth; dactylus long, curved distally acute.

Colouration. Body and appendages generally translucent, covered with tiny black chromatophores (I. Marin, pers. obs).

Size. Maximum length: ovigerous female, cl. 2.5 mm, pcl. 1.5 mm, tl. 6 mm; male, cl. 1.4 mm, pcl. 1.1 mm, tl. 5.5 mm. Egg number: 8, diameter 0.5 x 0.9 mm.

Ecology. In Nhatrang Bay, P. unciger lives on bushy black corals, Rhipidipathes sp., at depths between 40 and 50 m. Previous records of P. u n c i g e r from Antipathes colonies (e.g., Li 2000; Bruce 2005) need to be verified. A recent molecular revision of Antipathes and allied genera ( Lapian et al., 2007) resulted in the formal revalidation of Rhipidipathes Milne Edwards, 1857 . Since Antipathes and Rhipidipathes are very similar in external appearance, including the general morphology of the colony (see Tazioli et al., 2007, fig. 3), previous host records may well be misidentifications of Rhipidipathes sp.

Distribution. Indo-West Pacific: southern Red Sea (type locality), Kenya, Marquesas Islands ( Bruce, 2005), herewith reported for first time from Vietnam.

Remarks. The female from Nhatrang almost perfectly agrees with Calman’s (1939) description’s of P. unciger , e.g., in the similarly elongate rostrum, the shape of the supraorbital carina, the presence of fusiform setae on the second maxilliped, the shape of the fingers of the major second pereiopod, and finally by the small body size contrasting with the large egg size.

Figures

FIGURE 9. Pontonides unciger Calman, 1939. Ovigerous female (ZMMU 5490). A, habitus. B, front of carapace, dorsal view. C, mandible. D, maxillule. E, third maxilliped. F, second maxilliped. G, antenna. H, antennule. I, first pereiopod. J, first pereiopod, finger tips. K, major second pereiopod. L, minor second pereiopod. M, chela of major second pereiopod. N, chela of minor second pereiopod. O, third pereiopod. Scale bars: 1 mm (A); 0.8 mm (B, I, K, L, O); 0.5 mm (C – G, H, M, N); J drawn without scale.

FIGURE 10. Appendices masculinae. A, Pontonides maldivensis (Borradaile, 1915). B, Pontonides tatianae n. sp. C, Pontonides unciger Calman, 1939. D, Pontonides asperulatus Bruce, 2005.