Mursia xianshengi, Lai, Joelle C. Y. & Galil, Bella, 2006

Lai, Joelle C. Y. & Galil, Bella, 2006, A new species of Mursia Desmarest, 1823 (Crustacea: Decapoda: Calappidae) from the Andaman Sea, Zootaxa 1255, pp. 57-61 : 58-60

Mursia xianshengi n. sp.

( Figs. 1 A–C, 2A, B)

Mursia africana Ng et al., 2002: 356 [not M. africana Galil, 1993 ].

Material examined. Holotype, 1 male [42.2 by 55.5 mm (75.0 mm, including lateral spines)]; ZRC 1999.0086; trawled from the Andaman Sea, off Southern Thailand­Burma coast, 06º41.7’N 97º58.2’E, at depth 342 m, 20 March 1989.

Description. Carapace transversely subovate, convex, regions poorly marked, 1.35 wide as long (excluding lateral spines). Dorsal surface covered with closely­spaced perliform granules increasing in size laterally. Granular protuberances, diminishing in size posteriorly, disposed in 7 radial rows on dorsal surface of carapace. Mesogastric region highest part of carapace. Gastric, cardiac, intestinal regions separated from branchial regions by shallow, sinuous longitudinal grooves. Anterolateral margin arcuate, crenulate, denticulate and beaded. Lateral spine slim, acuminate, slightly curved upwards and forwards, about one sixth (0.17) carapace width, proximally granulate on upper surface. Posterolateral margins beaded, oblique, sharply convergent. Posterior margin intermittently beaded, lateral teeth triangular, dorsoventrally flattened, median lobe nearly obsolescent.

Front as wide as orbit. Frontal margin projecting beyond orbits, trilobate, median lobe broadly triangular, at lower plane than lateral lobes; lateral lobes rounded, separated from supraorbital margin by shallow concavity. Antennules obliquely folded. Supraorbital margin with a single slight fissure, minutely granulate, bearing long plumose setae. Inner orbital tooth separated from outer orbital margin by deep U­shaped cleft, and from front by orbital hiatus. Antennae small, slender, basal segment article subrectangular, lodged in orbital hiatus. Eyes retractable, eyestalk short, granulate, setose. Buccal frame rhomboidal, narrowing anteriorly. Thick fringe of plumose setae running the length of third maxilliped endopod, merus and ischium granulate, bearing short setae. Subhepatic region tomentose. Sternum granulose. Male abdomen with segments 3–5 fused; prominent trilobate carina on second segment, prominent subquadrate lateral lobes separated by narrow clefts from lower subquadrate median lobe (see fig 1A); sixth abdominal segment subquadrate, lateral margins sinuous; telson triangular, slightly shorter than sixth segment.

Chelipeds massive, granulate, nearly equal. Merus bispinose dorsodistally, distal spine longer, stouter than subdistal spine. Antero­distal margin of carpi ending in triangular denticle. External surface of manus convex, upper margin crested, setose. Larger chela bearing dorsal crest with seven denticles, teeth 1–3 successively larger, teeth 4–7 progressively more laciniate (numbered from proximal to distal). External surface prominently granulate, with 3 small granular tubercles near base of crest, several nearly effaced, granulate tubercles mid chela, and prominent, sinuous ridge, proximally unidentate, with closely granular margin, above lower margin. Internal surface with tomentose band near lower margin. Lower margin granulate, serrate, serrations successively smaller proximally. Upper margin of dactylus crested, setose, proximally granulate; with curved rounded tooth proximally fitting into depression in molariform tooth in pollex; inner surface of dactylus bearing stridulating ridge consisting of about 30 striae larger medially. Smaller chela lacks the large dactylar tooth. Pereopods 2–5 slender, laterally compressed, upper and lower margins minutely granulate; upper margin of carpi distally spinose; dactyli slender, longer than propodi, styliform.

First male pleopod tapering evenly, curved, distally spinulose. Second male pleopod long, slender; cornute, distal portion crook­shaped, tip twisted inwards, upcurved ( Fig. 2 A)

Distribution. Known only from type locality, Andaman Sea, off the Thailand­Burma coast.

Etymology. Xiansheng, honoured teacher, in Mandarin Chinese, in honour of Pat McLaughlin, for her contributions to the knowledge of decapod crustaceans.

Remarks. Mursia xianshengi resembles M. africana Galil, 1993 , M. buwaya Galil & Takeda, 2004 , M. flamma Galil, 1993 , and M. microspina Davie & Short, 1989 , in having the distal part of the second male pleopod crook­shaped. Mursia xianshengi differs from the latter two species in its longer lateral spine and from M. africana in the sculpture of the external surface of the chela, which in M. africana consists of twelve tubercles in total (nine tubercles in three oblique rows across the chela, and three tubercles near the base of serrated crest) and uniformly granulated throughout. It is most similar to M. buwaya , but may be distinguished from it based on its distinctly shorter and anteriorly curved lateral carapace spines ( Fig. 1 A, B), the prominent granulation on the external surface of the palm, and the difference in its sculpture, consisting of three small granular tubercles near base of the palmar crest, and several nearly effaced, granulate tubercles in the middle of the chela. M. buwaya bears two tubercles near base of crest, two widely spaced tubercles in the middle of the chela and three closely spaced tubercles just below the dactylar articulation ( Fig. 1 C–F). The shape of the trilobate carina of the second abdominal segment also differs between M. xianshengi and M. buwaya [subquadrate lateral lobes separated by narrow clefts from lower subquadrate median lobe versus rounded lateral lobes separated by wider clefts from median lobe ( Fig. 1 A, B)]. Examination of large series of Mursia specimens has shown that the length and form of the lateral spine and the sculpture of the external surface of the palm are species specific characters. Even though we had a single specimen of M. xianshengi , it was an adult male, and it was compared with several adult males of M. buwaya . The differences were consistent in all specimens examined.

Figures

FIGURE 1. Mursia xianshengi n. sp., male holotype, CL 42.2 mm, (ZRC 1999.0086); A, dorsal view; C, left cheliped, external surface; E, left cheliped, lower margin. Mursia buwaya male, CL 38.3 mm (ZRC 2001.0387) B, dorsal view; D, right cheliped, external surface; F, right cheliped, lower margin.

FIGURE 2. Mursia xianshengi n. sp., male holotype, CL 42.2 mm, (ZRC 1999.0086); second pleopod (A) with enlargement of distal part (B). Bar = 1 mm.