Mursia steinhardti, Galil, Bella S. & Ng, Peter K. L., 2009

Galil, Bella S. & Ng, Peter K. L., 2009, Calappoidea and Leucosioidea (Crustacea: Decapoda: Brachyura) from Luzon, Philippines, with descriptions of two new species of Mursia, Zootaxa 2085, pp. 45-60 : 50-53

Mursia steinhardti n. sp.

( Figs. 4 , 5 , 6 C, D)

Type material. Holotype, 3 (CL 27.4 mm) ( NMCR), stn. CP 2695, 14º46.25’N 123º40.11’E, 357 m, 26 May 2007.

Description. Carapace transversely subovate, convex, 1.2 times as wide as long. Dorsal surface covered with small flattened granules increasing in size laterally, larger granular protuberances disposed in 7 radial rows. Mesogastric region highest part of carapace; cardiac, intestinal regions separated from branchial regions by shallow, sinuous longitudinal grooves. Anterolateral margin arcuate, with beaded line superimposed on 9 tubercles, successively smaller anteriorly, posteriorly. Lateral spine 0.14 times carapace width, distally upcurved, dorsally granular. Posterolateral margins oblique, beaded, sharply convergent. Posterior carapace margin transverse, lateral teeth triangular, dorsoventrally flattened.

Front as wide as orbit, 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 entire, minutely granular, with long plumose setae. Inner orbital tooth separated from outer orbital margin by deep U-shaped cleft, from front by orbital hiatus. Antennae small, slender, basal segment subrectangular, lodged in orbital hiatus. Eyes retractable, eyestalk short, granular, setose. Buccal frame rhomboidal, narrowing anteriorly. Thick fringe of plumose setae running length of third maxilliped exopod; merus, ischium granular, with short setae. Subhepatic canal oblique, subhepatic region granular, setose. Surfaces of thoracic sternum minutely granular.

Chelipeds relatively massive, granular, subequal. Merus distally trispinose, distal spine nearly as long as lateral carapace spine, median spine half as long as distal spine, proximalmost spine minute. External surface of chela convex, upper margin crested, setose. Chela with dorsal crest bearing 8 denticles, successively larger distally. External surface of chela with 2 tubercles near base of crest; undulate ridge near lower margin proximally with triangular, dorsoventrally flattened, upcurved tooth, subsequent teeth rounded, subequal in size. Inner surface sparsely granular, with setose angled band near lower margin. Lower margin irregularly serrate, serrations successively smaller proximally. Upper margin of dactylus of larger chela crested, setose, proximally granular; with curved rounded tooth proximally fitting into depression formed between 2 molariform teeth in pollex; inner surface with stridulating ridge consisting of 28 striae, larger medially. Smaller chela lacks the large dactylar tooth, cutting edges of dactylus, pollex with rounded teeth. Pereiopods 2–5 slender, laterally compressed, upper, lower margins minutely granular; upper margin of carpus distally spinose; dactylus slender, longer than propodus, styliform.

Male abdomen with somites 3–5 fused; prominent trilobate carina on second segment, rounded lateral lobes separated by wide clefts from subrectangular median lobe; sixth abdominal segment subquadrate with sinuous lateral margins; telson forming equilateral triangle.

G1 evenly tapered, distally curved, spinulose. G2 long, slender; cornute, distal portion crook-shaped, tip twisted inwards, upcurved.

Colour. In life, dorsal surface of carapace and chelipeds pale orange, granules orange-red, carapace tubercles surrounded with crescentic reddish patches; pereiopods pale orange, colour slightly more intense distally ( Fig. 4 ). Outer surfaces of chelae orange with tubercles on inferior row white ( Fig. 4 A); inner surface of palm with small orange patch distally, near the articulation with the dactylus. Epistome with bright-red dots on each side of efferent channel.

Etymology. The species is named in honour of Mr. Michael Steinhardt, in grateful recognition of his support of the National Collections, Tel Aviv University.

Remarks. Mursia steinhardti n. sp. most closely resembles M. buwaya Galil & Takeda, 2004 , from the central Philippines in general body shape, shapes of the G1 and G2 as well as the colour pattern. It, however, differs markedly in the proportionally smaller size of its lateral carapace spine (0.14 times carapace CW against 0.20 times CW in M. buwaya ), and the shape of the ridge on lower external surface of the chela (ridge divided into four rounded teeth but with sinuous unbroken ridge in M. buwaya ).

With the discovery of the present two new species, 28 species of Mursia are now known, all from the Indo-West Pacific (see Lai & Galil 2006; Spiridonov & Apel 2007; Ng et al. 2008).

Distribution. Known only from the holotype.

Figures

FIGURE 4. Colour in life. Mursia steinhardti n. sp., holotype 3 (CL 27.4 mm) (NMCR), stn. CP 2695. A, overall view; B, dorsal view of carapace.

FIGURE 5. Mursia steinhardti n. sp., holotype 3 (CL 27.4 mm) (NMCR), stn. CP 2695. A, left G 1; B, distal part of left G 1; C, left G 2; D, distal portion of G 2. Scales = 1.0 mm.

FIGURE 6. Chelae. A, B, Mursia aurorae n. sp., holotype 3 (CL 31.4 mm) (NMCR), stn. CP 2741; C, D, M. steinhardti n. sp., holotype 3 (CL 27.4 mm) (NMCR), stn. CP 2695. A, C, external surface of right chelae; B, D, lower margin of right chelae.