Myra digitata, Galil, 2004

Galil, Bella S., 2004, A New Species Of Myra Leach, 1817 (Crustacea: Decapoda: Leucosiidae) From Timor Sea And South China Sea, Raffles Bulletin of Zoology 52 (1), pp. 215-217 : 215-216

Myra digitata , new species

( Figs. 1, 2A, B )

Myra biconica - Chen, 1989: 219, fig. 17, pl. 3.1; Chen & Sun, 2002: 351, textfig. 155, pl. 6 figs 1, 2.

Myra biconia - Chen, 1996: 285, fig. 13.

(Not Myra biconica Ihle, 1918: 258 , fig. 138).

Material examined. – Holotype - male (22.2 mm carapace length) (NHM 1892.3.26.173-180), Timor Sea, Holothuria Bank, 13º35’S

126ºE, 70 m depth, coll. P. Bassett Smith, H. M. S. ‘Penguin’, pres. Lords of the Admiralty.

Paratype - 1 female (23.6 mm carapace length), same data as holotype .

Diagnosis. – Carapace ovate, globose, regions indistinct ( Fig. 1). Dorsal surface of carapace finely granulate. Front narrow, produced, upcurved, anterior margin minutely granulate, with shallow v-shaped notch medially. Antennular fossa continuous with orbit, partially sealed by basal plate on antennule; antennules fold obliquely within fossa. Antennae short, inserted between antennular fossa and orbit. Orbits small, outer orbital margin trisutured, tridentate anterior margin of efferent branchial channel forms lower orbital margin. Eyes retractible. External maxillipeds minutely granulate; endopod merus triangulate, shorter than rectangular ischium, vertical row of setae on endopod merus and ischium in female. Hepatic region swollen, bearing minutely granulate line parallel with margin. Faceted subhepatic margin terminates in blunt, triangular denticle, separated from convex lateral margin by shallow notch. Lateral margins of carapace, from outer angle of efferent branchial channel to lateral posterior denticle, lined with closely-spaced granules. Lateral posterior denticles on lower plane than median posterior spine, bluntly triangular, granulate. Median posterior spine proximally granulate, distally acuminate, slightly upcurved.

Chelipeds slender, subequal; longer in adult male than in female specimens: merus in male up to 1.2 as long as carapace, in female slightly less than carapace length. Merus with perliform granules, smaller distally; carpus and propodus minutely granulate. Dactyl nearly as long as upper margin of palm, inner margins of fingers ctenoid. Pereiopods slender, dactyli styliform, setose, longer than propodi.

Thoracic sternites in male anterolaterally granulate, as well as subdistal margins of abdominal sulcus. Abdominal sulcus deep, elongate, nearly reaching buccal cavity. Male abdomen narrowly triangular; segments 3-6 fused, bearing preapical denticle; lateral margin bearing 3 indistinct ridges fitting into sutures between thoracic sternites; telson lingulate, one quarter as long as fused segment. Female abdomen with segments 4-6 fused, greatly enlarged, shield-like, telson laciniate. First male pleopod elongate, shaft straight, dorsoventrally flattened, bearing long setae preapically, apical process slender, digitiform, slightly leaning interiorly ( Figs. 2A, B ). Second male pleopod short, curved, apex scoop-like.

Etymology. – digitus L., finger, alluding to the form of the apical process of male 1 st pleopod.

than ovate, carapace, and rounded, less prominent lateral posterior denticles of carapace. Chen’s (1989: fig. 17, pl. 3.1; 1996: fig. 13) detailed drawings of the specimens collected in South China Sea, and of the male first pleopod in particular, closely resemble M. digitata . The pleopod of the new species is similar to that of M. grandis Zarenkov, 1990 , but M. digitata is easily distinguished from the latter species by its smaller size, and finely granulate, rather than smooth, carapace.

Distribution. – South China Sea, Timor Sea, 50- 140 m.

Figures

Fig. 2. Myra digitata, new species, holotype, 22.2 mm carapace length, NHM 1892.3.26.173-180.A, first male pleopod, dorsal view; B, first male pleopod, tip, ventral view. Scale 1 mm.