Cymo barunae, P.-H & Ng, 2005

P. - H & Ng, Peter K. L., 2005, On a new species of coral-symbiont crab of the genus Cymo de Haan, 1833 (Crustacea: Decapoda: Brachyura: Xanthidae), from the South China Sea, Zootaxa 1029, pp. 31-38 : 32-36

Cymo barunae n. sp. ( Figs. 1 –3)

Material. Holotype male, 10.0 by 10.2 mm, station EA­D11, in Acropora , fringing reef off rocky islet southeast of Pulau Laut , Natunas , Indonesia, South China Sea, 04°37'39.8"N, 107°58'18.1"E, coll. H. H. Tan et al., Expedition Anambas, Mar 2002, MZB Cru 1536 . Paratype female, 10.0 by 10.3 mm, same data as holotype, ZRC .

Comparative material of Cymo deplanatus . 2 males, 8.7 by 8.5 mm, 8.1 by 8.0 mm, 1 ovigerous female, 8.5 by 8.5 mm, Kabira Village , Ishigaki Island, Ryukyus, Japan, coll. Y. Nakasone, 17 Jul 1973, ZRC 1999.251 .

Description. Carapace longer than broad; surface and margins lined with and partially obscured by short plumose setae; dorsal surface generally smooth, with small low granules near anterolateral regions; regions poorly demarcated, grooves shallow ( Figs. 1, 2B, 3B); anterolateral margin shorter than posterolateral margin, gently convex, lined with small, low granules; one low granule at junction between antero­ and posterolateral margins; frontal margin bilobed, separated by deep V­shaped cleft, each lobe lined with long, sharp spines; lateral lobe of frontal margin separated from frontal lobes by distinct fissure, spiniform; supraorbital margin granular, with distinct submedian fissure; external orbital angle low, not spiniform; posterolateral margin almost straight to gently convex, converging towards distinctly concave posterior margin; suborbital margin gently concave, granular with 2 or 3 tubercles ( Figs. 1, 2, 3A–C).

Ocular peduncle short, with granule near base of cornea; basal antennal article (second article) subrectangular with lateral margins distinctly concave; antennular fossae rounded; antennules folding obliquely ( Fig. 3C). Third maxillipeds tomentose; ischium subrectangular, separated from basis by very shallow suture; merus squarish with angular antero­external edge ( Figs. 2A, 3H). Endopod of first maxilliped subovate, all margins rounded ( Fig. 3K, L).

Chelipeds asymmetrical, tomentose, surfaces partially obscured by setae, especially on outer surfaces of chelae and carpus; right chela larger in both sexes; outer surfaces of both palms covered with numerous sharp granules, some in rows; carpus rounded, outer surface covered with numerous sharp granules ( Figs. 1D, 2); fingers straight anteriorly with posterior part curving to spoon­shaped tip; male with entire finger pigmented brown except for white tip ( Figs. 1, 2A); female with proximal two­thirds of finger pigmented brown, distal one third white ( Fig. 2B).

Ambulatory legs short, tomentose, surfaces obscured by setae; margins of merus, carpus and propodus lined with short sharp granules; dactylus hooked, with well developed dactylo­propodal articulation ( Figs. 1, 2).

Anterior thoracic sternum lightly tomentose, relatively narrow; sternites 1 and 2 fused, separated from sternite 3 by distinct transverse suture; sternites 3 and 4 fused, lateral parts with faint trace of sutures; sternite 4 with longitudinal suture ( Fig. 3G). Male abdomen relatively slender; segments 3 to 5 fused with only lateral parts of suture between segments 3 and 4 visible; segment 6 almost squarish with lateral margins deeply concave; telson semicircular ( Fig. 3I). Female abdomen subovate, covering median part of thoracic sternum, lateral margins prominently setose ( Fig. 3J). G1 gently sinuous, distal part truncate, margins lined with stiff setae, with 1 long subdistal setae ( Fig. 3D–F). G2 very short.

Etymology. The species is named after the Indonesian research vessel “SS Baruna Jaya VIII”.

Remarks. Superficially, C. barunae n. sp resembles C. deplanatus in its more longitudinally subovate carapace shape, but that of C. barunae is relatively longer. While the carapace widths and lengths of C. deplanatus are subequal, in C. barunae , the carapace is longer. In addition, C. deplanatus appears to be a more tomentose species compared to C. barunae ( Fig. 1A) (cf. Serène 1984: pl. 2A). The spines on the frontal lobes are also very prominent and long in C. barunae ( Figs. 1B, 2B, 3A, B), more so than the specimens of C. deplanatus figured thus far (e.g. see Serène 1984: 2 A) or the similarly sized specimens from Japan examined here (see comparative material above). The endopod of the first maxilliped, a character introduced by Galil & Vannini (1990: 24, 25) to differentiate some of the Cymo species , also differs in shape, with that of C. barunae having a less convex distal margin and the postero­internal angle being rounded (not angular) compared to C. deplanatus (cf. Fig. 3K, L versus Galil & Vannini 1990: fig. 2A). The male telson of C. barunae is also distinctly semicircular in shape while that of C. deplanatus is distinctly more triangular in shape. The G1 structures differ markedly, with that of C. deplanatus having the distal part prominently hooked downwards (cf. Serène 1984: fig. 6) while that of C. barunae has a simple and subtruncate distal part ( Fig. 3D–F). Most prominently, the fingers of C. deplanatus are white or pale coloured while those of C. barunae are pigmented brown for at least two­thirds of their length ( Figs. 1, 2).

A colour photograph of the species was published by Yeo & Ng (2003: 3) as Cymo sp.