Mursia bicristimana Alcock & Anderson, 1894

Kumar, Biju A., Kumar, M. Sushil & Galil, Bella S., 2013, Calappid and leucosiid crabs (Crustacea: Decapoda: Brachyura) from Kerala, India, with the description of a new species of Mursia Desmarest, 1823, from the Arabian Sea and redescription of M. bicristimana Alcock & Anderson, 1894, Zootaxa 3746 (4), pp. 529-551 : 534-537

Mursia bicristimana Alcock & Anderson, 1894

( Figs 4 a–c, 5, 6a–d, 7a,b)

Mursia bicristimana Alcock & Anderson 1894a: 179 ; 1896, pl. 24, fig. 5.—Alcock 1896: 150; 1899: 5 (list), pl. 3, figs. 3, 3a, b.—Galil 1993: 356 (part).

Mursia africana —Ng et al. 2002: 356, not Mursia africana Galil, 1993 .

Mursia xienchengi Lai & Galil 2006: 58 , figs. 1a–c, 2a, b.

Not Mursia bicristimana Spiridonov & Apel 2007: 2859 , figs 5, 7a (part) = Mursia arabica n. sp.

Kerala material examined. Neendakara, 08˚56'N 76˚32'E, 70–100 m, 5 June 2007, 1 ♂ (CW 91.5 mm); 31 Aug. 2007, 2 ♀ (CW 73.0, 62.2 mm); 13 Sep. 2007, 2 ♂ (CW 89.5, 75.5 mm) 1 ♀ (CW 49.8 mm); 11 Oct. 2007, 1 ♂ (CW 78.6 mm); 27 Nov. 2007, 1 ♂ (CW 81.7 mm) (DABFUK). Munambam, 10˚11'N 76˚10'E, 70–100 m, 27 Aug. 2007, 1 ♂ (CW 80.0 mm) (DABFUK). Azhikkal, 11˚56'N 75˚17'E, 70–100 m, 21 Sep. 2007, 1 ♂ (CW 74.5 mm); 25 Oct. 2007, 1 ♀ (CW 49.8 mm) (DABFUK).

Additional material. Andaman Sea. International Indian Ocean Expedition, RV Anton Bruun, cruise 1, stn 22B, 10˚39’N, 97˚06’E, 94 m, 24 Mar. 1963, 2 ♂ (CW 58.6, 23.7 mm), 1 ♀ (CW 34.9 mm) (USNM 309672).

Redescription Carapace transversely subovate, convex, regions poorly marked, 1.4 as wide as long (excluding lateral spines) in male, 1.3 in female. Dorsal surface covered with closely-spaced granules increasing in size laterally ( Fig. 4 a). 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, with 11 granular denticles, denticles wider, lower, posteriorly. Lateral spine slim, acuminate, directed horizontally, about 0.15 carapace width, minutely granular on upper surface. Posterolateral margins closely beaded, cristate, nearly straight, sharply convergent. Posterior margin beaded, lateral teeth triangular, dorsoventrally flattened, median lobe obsolescent. Front as wide as orbit, setose. Frontal margin projecting beyond orbits, trilobate, median lobe on lower plane than lateral lobes, triangular, tip up-curved; lateral lobes rounded, separated from supraorbital margin by shallow concavity. Antennules obliquely folded. Supraorbital margin with single fissure, closely granular, with long plumose setae. Inner orbital tooth ogive, separated from outer orbital margin by U-shaped cleft, from front by orbital hiatus. Antennae small, slender, basal segment article subrectangular, lodged in orbital hiatus. Eyes retractable, eyestalk short, granular, setose. Buccal frame rhomboidal, narrowing anteriorly. Third maxilliped exopod thickly fringed with plumose setae. Ischium of third maxilliped endopod bears granular ridge parallel with distal margin which forms stridulating organ when rasped against milled ridge on dactylus of chela. Subhepatic region tomentose. Sternum granular. Male abdomen with prominent trilobate carina on second somite, rounded lateral lobes separated from wider, subrectangular median lobe; somites 3–5 fused; sixth abdominal somite subquadrate, lateral margins sinuous, distally with rounded concavities fitting conic ‘buttons’ raised on the margins of abdominal cavity; telson equilateral triangular, shorter than sixth somite. Female abdomen with somites 3–6 articulate; sixth abdominal somite trapezoid, lateral margins sinuous, distally with rounded concavities fitting conic ‘buttons’ raised on the margins of abdominal cavity; telson ogival, longer than sixth somite. Chelipeds massive, subequal ( Fig. 4 b, c). Merus bispinose dorsodistally, distal spine longer, stouter than subdistal spine. Antero-distal margin of carpus ending in triangular denticle. Upper margin of manus crested, setose, with 7 denticles, 3 proximal teeth successively larger, distal teeth laciniate. External surface of manus prominently granular, 3 granular elliptoid tubercles horizontally mid-chela, keel-like, indistinctly trilobate sinuous ridge above lower margin, proximal lobe ram-like, margin closely granular. Lower margin granular, serrate, serrations successively smaller proximally. Internal surface of manus with tomentose band near lower margin. Upper margin of dactylus crested, setose, proximally prominently granular; inner surface of dactylus with stridulating ridge consisting of about 30 striae, elongate and closely stacked proximally, rounded and spaced in distal third. Right chela with curved rounded tooth proximally fitting into depression in molariform tooth in pollex. Pereiopods 2–5 long, slender, laterally compressed; upper and lower margins of meri 2–5 densely granular; carpi 2,3 with three granular carinae, middle carina more prominently granular, distally spinose, carpus 4 with two granular carina, distally spinose, carpus 5 with obsolete carinae, lacking terminal spine; propodi 2–4 with cristate, granular upper margin, crested upper margin of fifth propodus smooth, slanted posteriorly; dactyli longer than propodi, styliform, fluted, tips corneous. First male gonopod tapering evenly, curved, distally spinous ( Fig. 6 a–d). Second male gonopod long, slender; corneous distal portion gentle crook-shaped, tip twisted inwards, up-curved ( Fig. 7 a, b). Female abdominal cavity densely set with minute setae, distally (area covered by telson) with patches of longer setae. Genital opening covered with rounded conic cap bordered by shiny protuberance laterally, triangular knob mesially.

Colour. In preserved specimens carapace pale salmon, with traces of orange-red reticulations, outer surface of manus salmon, granular tubercles bone coloured, horizontal ridge, lower margin, pollex and dactyl white. Inner surface of merus bright red; red spot distally on upper inner surface of manus, near dactylar articulation and a diffuse reddish spot proximally on dactyl.

Remarks. The genus suffered from taxonomic confusion due to the relative rarity and superficial resemblances of its species. Twenty-eight species are known, of which thirteen have been described in the past two decades. Mursia bicristimana was described and illustrated from a single pre-adult female (CL 21 mm) from the Gulf of Manaar (Alcock & Anderson 1894a: 179; 1896, pl. 24, fig. 5) ( Fig. 5 ). A larger male specimen (CL 47 mm) subsequently collected off Colombo, Sri Lanka, was listed by Alcock (1896: 150; 1899: 23, pl. 3, figs 3, 3a, b) and Alcock & Anderson (1896, pl. 24, fig. 5). These specimens, deposited in the collections of the Zoological Survey of India, Calcutta, were unavailable for examination. Therefore Galil (1993: 356, figs. 1f, 3j–k, 5c–d) based her description and illustrations of M. bicristimana (1993: 356, figs. 1f, 3j–k, 5c–d) on a pre-adult male specimen (CL 19.1 mm, NHM 1898.8.26.3) labeled “ Syntype? Alcock det., 11˚14’30"N 74˚57’15"E, 68–140 fathoms, coll. Indian Museum”. Spiridonov & Apel (2007: 2861) pointed out that the presumed syntype specimen was most probably “collected at a different locality and four years after the description of M. bicristimana was published” and consequently could not have been a syntype. Spiridonov & Apel (2007) assigned the specimen from Lakshadweep (= Laccadive Is) to a new species, M. minuta Spiridonov & Apel, 2007 , and noted that the lateral spines “in adult specimens from the Andaman Sea and the Nicobars reach about 0.15–0.18 times CW, while the Gulf of Aden specimens have somewhat shorter spines reaching only about 0.10 times CW in adult specimens”, but opted not to take “further taxonomic and nomenclatural actions” pending comparison with the type material of Alcock (Spiridonov & Apel 2007: 2866). Owing to the erroneous labeling of the NHM material and resulting misidentification, a large male specimen (CL 42.2 mm) collected in the Andaman Sea (ZRC 1999.0086) was misidentified, first as M. africana (Ng et al. 2002), and then as a new species (Lai & Galil 2006).

Although the types of M. bicristimana could not be examined, careful scrutiny of the descriptions and illustrations (Alcock & Anderson 1894a: 179; 1896, pl. 24, fig. 5; Alcock 1896: 150; 1899: 23, pl. 3, figs. 3, 3a, b, fig. 5) allows assigning the Kerala material, as well as to the specimens collected in the Andaman Sea (USNM 309672), to M. bicristimana . The general form and carapace proportions, and the characteristic palmar crest, (“sharp crest, the edge of which is unevenly trilobed, the proximal lobe being short acute and spiniform, the middle lobe being broad and obtuse, and the distal lobe being narrow and obtuse”; Alcock & Anderson 1894a: 179) are similar, as is the straight postero-lateral margin (“the postero-lateral margins are without the angular bend inward”; Alcock, 1896: 150). The specimens collected in the Gulf of Aden, having noticeably shorter lateral spines, undulating postero-lateral margin, and differing in the shape of palmar crest, dactylar stridulating ridge and female genital opening cap, are here referred to as a new species of Mursia .

Distribution. Known from the Gulf of Manaar (Alcock & Anderson 1894a), Sri Lanka and the Andaman Sea. New record for Kerala.

Figures

FIGURE 4. Mursia bicristimana Alcock & Anderson 1894, Neendakara, India, 5 Jun 2007, ♂, CW 91.5 mm; a. dorsal view of carapace; b. external view of chelae; c. ventral view of chelae. Photo by Phil Hurst, NHM Photo Unit.

FIGURE 5. Mursia bicristimana Alcock & Anderson 1894, from Alcock & Anderson 1896, pl. 24, fig. 5; from Alcock 1899, 23, pl. 3, figs. 3, 3 b.

FIGURE 6. Mursia bicristimana Alcock & Anderson 1894, Neendakara, India, 5 Jun 2007, ♂, CW 91.5 mm; right first gonopod, ventral view; a. entire; b. distal end; dorsal view; c. entire; d. distal end.

FIGURE 7. Right male second gonopod, Mursia bicristimana Alcock & Anderson, 1894, Neendakara, India, 5 June 2007, ♂, CW 91.5 mm, a. entire view; b. distal end; M. arabica n. sp., Holotype. Gulf of Aden, John Murray Expedition, ♂, CW 59.3 mm, stn 35, 13 ° 14 ' 24 " N 46 ° 14 ' 12 " E, 16 Nov. 1933, c. entire view; d. distal end; Urashima lamellidentata (Wood-Mason, 1892), Neendakara, 08 ˚ 56 ' N 76 ˚ 32 ' E, 31 Aug. 2007, ♂, CW 38.1 mm, e. entire view.