Pontonides tatianae, Marin, Ivan, 2007

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 : 13-15

Pontonides tatianae n. sp.

( Fig. 8 )

Type material. Holotype. Vietnam, Nhatrang Bay: female (pcl. 1.8 mm), Dun I., on black coral Rhipidipathes sp., depth 40 m, coll. I. Marin, 2 June 2006 ( ZMMU Ma 5489).

Diagnosis. Small-sized pontoniine shrimps with subcylindrical body. Carapace smooth, not gibbous. Rostrum long, overreaching distal margin of basal antennular segment. Supraorbital margin well developed, rectangular, with small tooth; orbits well developed. Eyestalk without dorsal tubercle. Fourth and fifth pleura rounded. Second maxilliped without fusiform setae. Third maxilliped with numerous fusiform setae on proximal half of basal segment. First to fifth pereiopods without fusiform setae on ischia. Second pereiopods unequal; major chela covered with tiny tubercles, setose, fingers stout and curved; minor chela sparsely setose; fingers 2–2.5 times as long as wide, with curved tips. Third pereiopods setose; dactylus simple, curved, acute distally.

Description. Female holotype, tl. 3.1 mm, pcl. 1.8 mm. Carapace smooth, not gibbous, with well developed antennal tooth; hepatic tooth absent; anterolateral angle broadly concave. Rostrum slender, elongate, overreaching distal margin of basal antennular segment, oval in cross-section ( Fig. 8 B, C). Supraorbital carina well developed, rectangular, with small teeth, broadly expanding over proximal portion of eyes, reaching midlength of rostrum.

Abdominal somites smooth, tergites non-carinate or posteriorly produced; pleura of first to fifth abdominal somites posteroventrally rounded ( Fig. 8 A). Telson slender, about four times as long as wide, not tapering distally, with two pairs of small slender submarginal dorsal spines situated at about 0.5 and 0.8 of telson length, respectively; posterior margin with three pairs of spines: short lateral spines, longer slender intermediate spines, and slender plumose submedian spines, latter about half length of intermediate spines ( Fig. 8 D).

Eyes large, well-developed; cornea and eyestalk rounded.

Antennules ( Fig. 8 E) with basal segment about twice as long as wide; lateral margin with strong acute distolateral tooth and distinct. Antenna with distolateral margin of basicerite rounded, without distolateral tooth; scaphocerite broad, not exceeding antennular peduncle and rostrum, about 1.5 times as long as maximum width, with well developed distolateral tooth.

Mouthparts without specific features, typical for genus. Mandible ( Fig. 8 F) without palp; incisor process slender, tapering distally, with four terminal teeth; molar process well developed. Maxillula normal; palp well developed, bilobed; upper lacinia larger than lower, slightly tapering distally, with strong distal spines; lower lacinia slender, distally rounded, with distal setae. Maxilla with well developed simple rounded palp. First maxilliped ( Fig. 8 G) with completely fused endites; palp with distal setae; exopod greatly reduced. Second maxilliped with ischium furnished with several simple setae in central portion of mesial margin; epipod oval, without podobranch. Third maxilliped ( Fig. 8 H) with broad segments; basal segment with numerous fusiform setae along proximal half of lateral margin; exopod well developed; arthrobranch present.

First pereiopods slender, unarmed; palm twice as long as wide, subcylindrical; fingers slender, about three times as long as wide, with straight cutting edges and row of stiff setae near tips. Second pereiopods unequal; major chela ( Fig. 8 I) with papillose and setose palm; fingers stout, about twice as long as wide, curved, with well developed dentate cutting edges ( Fig. 8 L); minor chela ( Fig. 8 J) with smooth but setose palm; fingers slender about four times as long as wide, with straight cutting edges. Third to fifth pereiopods ( Fig. 8 K) stout, smooth; dactylus simple, curved, distally acute ( Fig. 8 M). Pleopods not especially modified. Uropods slender, exceeding telson; lateral margin of endopod with small movable spine, without distal tooth.

Male unknown.

Colouration. Body and appendages generally translucent, covered with tiny black chromatophores; longitudinal dark-blue band extending lateroventrally from anterior carapace to sixth abdominal segment (I. Marin, pers. obs.).

Size. Non-ovigerous female holotype (only specimen known), with cl. 2.3 mm, pcl. 1.8 mm, tl. 3.1 mm.

Type locality. Nhatrang Bay, Vietnam.

Etymology. The species is named in honour of my mother, Tatiana Marina, and Tatiana Anker, mother of Arthur Anker.

Ecology. The species was found on a colony of the bushy black coral, Rhipidipathes sp. ( Antipatharia , Antipathidae ) at a depth of about 40 meters. The shrimps were found at the base of the colony, clinging to the branches.

Distribution. Western Pacific: presently known only from the type locality in Vietnam.

Systematic position. Pontonides tatianae n. sp. shares with P. a s p e r u l a t u s and P. u n c i g e r the presence of a long rostrum (reaching to the distal margin of the proximal segment of the antennular peduncle), the supraorbital carina bearing a sharp tooth, the major chela of the second pereiopods being covered with small tubercles, and the marginal position of the dorsal spines of the telson. This unique feature combination suggests that P. tataianae n. sp., P. asperulatus and P. unciger form a morphologically well-defined group within Pontonides (see also Bruce 2005). Pontonides tatianae n. sp. differs from P. asperulatus by the smaller size, and the rounded posteroventral margins of the abdominal pleura. Furthermore the two species have different colour patterns and are associated with different hosts. The rounded pleura of the fourth and fifth abdominal segments and the absence of fusiform setae on the second maxilliped enable to separate P. tatianae n. sp. from P. unciger , which also associates with Rhipidipathes sp. (see below).

Figures

FIGURE 8. Pontonides tatianae n. sp. Female holotype (ZMMU Ma 5489). A, habitus. B, front of carapace, dorsal view. C, front of carapace, lateral view; D, telson, E, antennule; F, mandible; G, second maxilliped. H, third maxilliped. I, major second pereiopod. J, minor second pereiopod. K, fingers of major second pereiopod. L, third pereiopod. M, third pereiopod, dactylus. Scale bars: 2 mm (A); 1 mm (B – D, I – K); 0.7 mm (E, F); 0.5 mm (G, H, L, M).