Heteronucia margaritata, 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 : 61-64

Heteronucia margaritata , new species

( Figs. 1A , 2)

Material examined. – Holotype - male (3.0 by 3.5 mm) ( ZRC 1993.263 ), Cyrene Reef , on Pavona coral, Singapore, coll. 15 Aug.1986.

Diagnosis. – Carapace polygonal, regions distinct; median part with well delimited triangular area (including gastric, cardiac and intestinal regions), intestinal region relatively convex; dorsal surface of each region covered with unequally sized pearl-like granules. Hepatic region depressed, subhepatic region produced into large tubercle. Front with 2 rounded lobes, margins with small tubercles. Anterolateral margin longer than posterolateral margin, with 3 lobes, first one larger than posterior two; each lobe with tubercles of unequal sizes along edges. Posterior carapace margin straight, lined with relatively larger tubercles. Surface of third maxilliped covered with tubercles, exopod stout, distal end rounded, only reaching to base of merus; merus triangular; ischium long, twice length of merus. Chelipeds stout, short, covered with tubercles; merus stout, dilated medially, about twice as long as broad; carpus small; palm ca. 1.50 times as long as broad; movable finger shorter than palm, opening vertically, cutting edges of fingers with small blunt teeth. Dorsal and ventral surfaces of last ambulatory leg with small tubercles; dactylus lanceolate. Surface of abdomen with flattened rounded tubercles of different sizes; first 2 segments small, transversely narrow; segments 3-5 fused; segment 6 broader than long; telson triangular, slightly longer than broad. G1 slender, long, slightly curved basally, distal part with 2 thin blade-like processes, basally surrounded by long setae of unequal lengths.

Etymology. – The name is derived from the Latin “margaritatus” for adorned with pearls, alluding to the pattern of granules on the carapace.

Remarks. – Heteronucia margaritata , new species, most closely resembles H. xincunensis Chen & Türkay, 2001 , from Hainan Island. We have compared the type specimens of both species, and H. margaritata can be separated from H. xincunensis in having a slightly broader carapace (ca. 1.17 times as broad as long) (vs. ca. 1.14 times as broad as long), the dorsal surface of the carapace has numerous unequally sized pearl-like granules (vs. with numerous fine vesicular granules), the ischium, merus and exopod of the third maxilliped are proportionately longer (length to width ratio of merus ca. 2.0 vs. 1.60), the surface of the merus of the third maxilliped has coarse granules (vs. with smooth granules), the merus of the cheliped is relatively more slender (length to width ratio ca. 2.0 vs. 1.50), the palm of the cheliped is proportionately longer (length to width ratio ca. 1.50 vs. 1.0), the merus of the last ambulatory leg is ca. 2.50 times as long as broad (vs. 2.0 times as long as broad), and the blade-like distal part of the Gl is relatively stouter (vs. relatively more slender). (see also Chen & Türkay, 2001: 245, Fig. 4 ).

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.

Fig. 4. Leucosia major, new species. A-C, E-H, paratype female (36.0 by 31.9 mm) (ZRC 1985.79); D, I-L, holotype male (38.0 by 34.0 mm) (ZRC 19984.50). A, carapace; B, front; C, thoracic sinus; D, right cheliped; E, fourth left ambulatory leg; F, female genital opening; G, right third maxilliped; H, female abdomen; I, male abdomen; J, lateral view of male abdominal segment 6 and telson; K, G1; L, distal part of G1. Scales = 5.0 mm.