Leucosia major, H.-L. & Ng, 2003

H. - L., Chen & Ng, Peter K. L., 2003, On New Species Of Leucosiidae (Crustacea: Decapoda: Brachyura) From Singapore And The South China Sea, Raffles Bulletin of Zoology 51 (1), pp. 61-69 : 64-67

Leucosia major , new species

( Figs. 1 C-F, 4)

Material examined. – Holotype - male (38.0 by 34.0mm) ( ZRC 1984.50 ), South China Sea, off Singapore, coll. H. Huat, 26 Nov.1982.

Paratypes – 1 male (37.1 by 32.0 mm) ( ZRC 1984.6325 ), 1 ovigerous female (38.5 by 39.0 mm) ( ZRC 1984.6326 ), South China Sea, off Singapore, about 30 miles from Horsburgh Lighthouse, coll. H. Huat , 1980s; 1 female (36.0 by 31.9 mm) ( ZRC 1985.79 ), South China Sea, station B77, 6-7 fathoms, mud, coll. Singapore Fisheries Research Center, 1955-1956 .

Diagnosis. – Carapace somewhat rhomboidal, 1.12-1.16 times as long as broad. Median part, from front to intestinal

region more convex than lateral sides. Hepatic region slightly elevated, other regions indistinct. Front divided into 3 teeth: median tooth produced anteriorly downwards, broad, long, lateral teeth bluntly narrow, short, distal ends of all 3 teeth bluntly rounded. Anterolateral margin and distal half of posterolateral margin with fine granules. Posterior carapace margin with distinct granules. Thoracic sinus shallow, with setae, base of sinus with 7 granular tubercles, of which first and seventh tubercles smaller than others, with 2-3 fine granules behind seventh tubercle. Exopod of third maxilliped slender, long, 4.5 times as long as broad, distal end reaching distal part of merus of endopod; merus narrowly triangular, 2.5 times as long as broad, longer than ischium; distal part of female ischium elevated, inner side and base of merus with longitudinal row of setae; male ischium not elevated, glabrous. Chelipeds stout, merus twice as long as broad, distal end broader than basal half, median part of distal one-third elevated, dorsum of distal two-thirds smooth, without granules, dorsal surface of basal half near outer border with patch of 10 fine granules, anterior part with 2 longitudinal rows of 2 or 3 similarly shaped granules; carpus subglobate; palm flattened, 1.5 times as long as broad, borders thin, inner border with coarse granules; movable finger shorter than palm, cutting edges of both fingers with indistinct teeth. First pair of ambulatory legs longest, other legs gradually shorter, last pair shortest. Male abdomen with 5 free segments; segments 3-5 fused, stout, short, borders sinuous; segment 1 short, broad; segment 2 very small; segment 6 broad, flattened, distal part of borders narrowed; telson equilaterally triangular. Female abdomen longitudinally ovate, segments 3-6 fused, stout, large, suture between fused third and fourth segments visible; segment 1 very short, visible only laterally; median part pf segment 2 protruding posteriorly; telson triangular, 1.18 times as long as broad, borders with short setae. G1 stout, sinuous, distal part corneous, hard, yellow (in preservative), surrounded by long setae, finger-like process slightly curving inwards.

Color (in alcohol). – Anterior two-thirds of carapace grayish brown, posterior one-third pale brown, each side of meso- gastric region with 4 white spots in 2 oblique rows followed by longitudinal rows of white stripes. Each side of cardiac region with indistinct black blotch.

Etymology. – The name is derived from the Latin for large, alluding to the relatively large size of the species.

Remarks. – This new species closely resembles Leucosia magna Tyndale-Biscoe & George, 1962 , and L. singaporensis , new species, in the carapace shape and structure of the thoracic sinus. The differences between these species are summarised in Table 1.

Figures

Fig. 1. A, Heteronucia margaritata, new species: holotype male (3.0 by 3.5mm) (ZRC 1993.263); B, Pseudophilyra punctulata, new species: paratype female (6.0 by 5.4 mm) (ZRC 1995.550); C-F, Leucosia major, new species, C: holotype male (38.0 by 34.0mm) (ZRC 1984.50), D, paratype male (37.1 by 32.0 mm) (ZRC 1984.6325), E, F, paratype female (36.0 by 31.9 mm) (ZRC 1984.6326); G, H, Leucosia singaporensis, new species: holotype male (28.0 by 24.0 mm) (ZRC 1965.10.13.49). A-C, E, G = dorsal views; D, F, H = ventral views.