Leptodius exaratus (H. Milne Edwards, 1834 )

Lee, Sang-kyu, Mendoza, Jose Christopher E., Ng, Peter K. L. & Kim, Won, 2013, On The Identity Of The Indo-West Pacific Littoral Xanthid Crab, Leptodius Exaratus (H. Milne Edwards, 1834) (Crustacea: Decapoda: Brachyura: Xanthidae), Raffles Bulletin of Zoology 61 (1), pp. 189-204 : 190-192

Leptodius exaratus (H. Milne Edwards, 1834) , sensu stricto

( Figs. 2 , 4A–D )

Cancer inaequalis, Audouin, 1826: 86 [ Egypt]; Savigny, 1809: pl. 5 fig. 7 [ Egypt] [not Cancer inaequalis Olivier, 1791 ]

Chlorodius exaratus H. Milne Edwards, 1834: 402 ; 1849: pl. 11 fig. 3 [ India]

Leptodius exaratus , A. Milne-Edwards, 1868: 71 [ Madagascar]; Richters, 1880: 148 [ Mauritius, Seychelles]; Nobili, 1906a: 121 [Persian Gulf]; 1906b: 240 [Red Sea]; Rathbun, 1911: 215 [Saya de Malha Bank, Madagascar]; Lenz, 1912: 3 [Africa]; Klunzinger, 1913: 209, pl. 3, fig. 6, pl. 5, fig. 16 [Red Sea]; Bouvier, 1915: 284 [ Mauritius]; Balss, 1924: 10 [Red Sea]; Pesta, 1928: 72 [ Sudan]; Maccagno, 1936: 174 [Red Sea]; Ramadan, 1936: 32 [Red Sea]; Chopra & Das, 1937: 398 (in part) [Arabian Sea, Persian Gulf]; Forest & Guinot, 1961: 63, fig. 54 [Aldabra Is.]; Guinot, 1964: 11 [Aldabra Is., Madagascar]; 1967: 265 [Indian Ocean]; Serène, 1968: 75 (in part) [Indian Ocean]; Khan, 1977: 181, pl. 1D [ Pakistan]; Kensley, 1981: 44 [ South Africa]; Serène, 1984: 184, fig. 106, pl. 26 fig. A [ Madagascar, Aldabra]; Tirmizi & Ghani, 1996: 48, fig. 18 [ Pakistan]; Guinot & Cleva, 2009: 106, with figures [Egyptian Red Sea]

Actaeodes lividus Paul’son, 1875: 35, pl. 5 fig. 2 [Red Sea]

Chlorodius (Leptodius) exaratus, Kossmann, 1877: 32 , pl. 2, figs. 1–6 [Red Sea]

Xantho exaratus var. typica Ortmann, 1893: 445 (in part) [Red Sea]

Xantho (Leptodius) exaratus, Alcock, 1898: 118 [353] (in part) [western India, Pakistan, Persian Gulf]; Stephensen, 1946: 149, fig. 37c [Persian Gulf]; Guinot, 1958: 92 [ Mayotte Is.]; Michel, 1964: 32 [ Mauritius]

Xantho hydrophilus, Laurie, 1915: 444 , pl. 43, fig. 1 [ Sudan] [not Cancer hydrophilus Herbst, 1790 ]

Xantho exaratus, Monod, 1938: 125 , fig. 17B [Egyptian Red Sea]; Vatova, 1943: 19 [ Somalia]; Buitendijk, 1960: 331 (in part) [ South Africa]

Xantho (Leptodius) hydrophilus, Barnard, 1950: 223 , fig. 41c, 42c–e [ South Africa] [not Cancer hydrophilus Herbst, 1790 ]

Type locality. — Coasts of India (H. Milne Edwards, 1834: 402) .

Material examined. — Neotype (here designated): male (23.7 × 16.1 mm; NHM 1881.10 ), Karachi , Pakistan.

Others: Pakistan – 1 ovig. female (29.4 × 19.1 mm; NHM 1881.10), Karachi; 1 male (30.0 × 19.4 mm), 1 female (23.4 × 14.9 mm) ( ZRC 2010.0073 ), Buleji, 24 Feb.1982 . Western India – 3 males (23.3 × 13.3 mm – 35.7 × 23.2 mm), 1 female (24.1 × 15.5 mm; NHM 1889.6.17.112–115), Bombay (?), no further data. Persian Gulf – 1 female (26.6 × 17.3 mm; NHM 1979.272 ), Fairlakka Is., Kuwait, coll. D.A. Clayton, 5 May 1979 ; 2 males (26.3 × 17.8 mm, 29.5 × 19.0 mm; NHM 1985.55 ), Bandar-e-Abbas, Iran, coll. H. Fakow, 22 Feb.1976 ; 2 males (20.6 × 13.9 mm; 25.8 × 17.1 mm, with sacculinid), 1 female (20.3 × 13.7 mm; NHM 2012.1027 – 1029 ), Ras Al Jlay’ah, Kuwait, coll. D. Clayton, 25 Oct.1979 ; 2 males (25.4 × 16.7 mm, with sacculinid; 25.5 × 16.4 mm), 1 female (17.1 × 11.8 mm; NHM 2012.1030 – 1032 ), Al-Wusail, Qatar, coll. 25 Mar.1983 , don. G. Bradley; 9 males (12.2 × 8.0 mm – 29.9 × 18.9 mm), 7 females (15.5 × 11.1 mm – 20.4 × 13.2 mm; ZRC 2012.0111 ), Qushm Is., Iran, coll. M. Asgari, 19 Nov.2008 . Madagascar – 2 males (13.6 × 9.1 mm, 21.5 × 14.2 mm; MNHN-B6640 ), Nosy Be, coll. P. Opic, 20 May 1923 ; 4 females (10.0 × 6.8 mm – 14.0 × 9.0 mm; MNHN-B15992 ), Nosy Be, coll. A. Crosnier, Sep.1958 . Seychelles – 2 males (17.6 × 12.0 mm, 18.6 × 12.5 mm) , 2 females (17.4 × 11.6 mm, 17.6 × 11.2 mm) ( MNHN-B8623 ), Aldabra, coll. Calypso Expedition, May 1954 .

margin with wide V-shaped notch medially; ischium subrectangular with submedian sulcus, smooth to punctate; exopod stout, length about 4 times width.

Thoracic sternum ( Fig. 2B ) finely granular, glabrous. Sternites 1, 2 completely fused, separated from sternite 3 by distinct suture; sternites 3, 4 almost completely fused except for short notches laterally, sternite 3 distinguishable from sternite 4 by shallow groove; sternite 4 large, inflated; sternites 5–8 distinct, separate, sternite 8 not visible externally. Median longitudinal line visible externally only on central portion of sternite 4; within sternoabdominal cavity, visible only at posterior portion of sternite 4, complete at level of sternites 6, 7, 8. Sternal press-button situated on sternite 5, equidistant from sutures 4/5, 5/6.

Chelipeds ( Fig. 2A ) unequal. Merus with long setae on anterior and posterior borders. Carpus finely granular, rugose on external surface, with blunt tooth on inner angle. Palm Description. — Carapace ( Fig. 2A ) transversely subovate, about 1.5–1.6 times as broad as long; dorsal surface somewhat convex, finely granular, rugose particularly at anterior and lateral regions; regions well defined, separated by distinct grooves; 2F separated from 1M by shallow, transverse groove; 2M partly divided longitudinally, 1M fused to inner branch of 2M; 3M, 2L, 3L, 4L, 5L, 6L distinct, entire; 4M indistinct; 1L very small; 1 R, 2 R fused, separated from 3 R by indistinct oblique groove; 1P, 2P indistinct. Front about 0.2–0.3 times as broad as carapace breadth, not much protruded; margin deeply sinuous medially, almost quadridentate; separated from inner orbital tooth by notch. Orbit small, oval; superior margin with 2 fissures; inferior margin bearing 2 blunt teeth on either side; exorbital angle separated from first anterolateral tooth on anterolateral margin by shallow concavity. Anterolateral margin with 4 broad, triangular teeth behind exorbital angle: first small, acute; second broad, large; third similar to second, slightly more produced; last small, most acute. Posterolateral margin somewhat concave. Posterior margin granular, central region straight. Pterygostomian region granular, setose.

Antennules ( Fig. 2B, C ) folding transversely, slightly obliquely. Basal article of antenna sub-rhomboidal, short, broad; antennal flagellum entering orbital hiatus. Epistome narrow; central region with median projection, separated from lateral regions by distinct notches. Third maxilliped completely covering buccal orifice; merus subquadrate, granular, anterolateral angle slightly produced, anterior inflated, rugose dorsally, smooth ventrally. Fingers stout, darkly pigmented throughout length, except at tips with white colour, pigment on fixed finger extending minimally into palm; gape moderately wide; cutting margins irregularly dentate; finger tips spoon-shaped, hollowed out, with tufts of setae.

Ambulatory legs ( Fig. 2A ) short, stout; anterior margins finely granular; anterior and posterior margins of meri with long setae; carpi, propodi subequal in length, sparsely setose; dactyli tomentose, spinose, ending distally in long, chitinous claw.

Male abdomen ( Fig. 2B ) narrow; somites 3–5 fused, sutures vaguely discernible; somite 6 long, median length about 1.6 times that of telson, distal half slightly broader than proximal half, lateral margins slightly concave. Telson subtriangular, tip broadly rounded; tip not reaching level of sternal condyles of P1 coxae.

G1 ( Figs. 4A–D ) long, slender, with 6–8 stout, curved subdistal spines; with elongate apical lobe set at slight angle with rest of G1, with 8-10 mushroom-shaped marginal outgrowths; apical lobe about 0.05–0.07 times total length. G2 about quarter length of G1.

Remarks. — Henri Milne Edwards (1834: 402) described Chlorodius exaratus from an unspecified number of specimens collected from “les côtes de l’Inde”. He later provided an illustration of this species (H. Milne Edwards, 1849: pl. 11 fig. 3), presumably of the type or from the type series. The genus Leptodius was later established by A. Milne-Edwards (1863) for the species.

The present specimens agree with the description and illustrations of Leptodius exaratus (e.g., H. Milne Edwards, 1849: pl. 11 fig. 3; Barnard, 1950: 223, figs. 41c, 42c, e; Serène, 1984: 180, pl. 26 fig. A), particularly in the form of the G1 (e.g., Stephensen, 1946: fig. 37C, Barnard, 1950: fig. 42d; Forest & Guinot, 1961: fig. 54; Serène, 1984: fig. 106). The type, thus far, has not been found in the MNHN, where H. Milne Edwards’ types are deposited, despite repeated attempts to locate it. It is reasonable to assume that the type is lost and, therefore, a neotype must now be selected to stabilise the complex taxonomy of this species (see Discussion). A topotypic specimen (a male, 23.7 × 16.1 mm; NHM 1881.10) from the western coast of the Indian subcontinent (Karachi, Pakistan) is hereby selected as the neotype for Chlorodius exaratus H. Milne Edwards, 1834 . Differences between L. exaratus s. str. and its close sibling L. affinis (De Haan, 1835) are discussed under the Remarks for the latter.

Distribution. — Leptodius exaratus s. str. is found in the Western Indian Ocean, ranging from the eastern and southern coasts of Africa, including Madagascar, to the western coast of India; and also in the Red Sea and the Persian Gulf. It has been reported from the following localities:

Western Indian Ocean: Western India (H. Milne Edwards, 1834; Alcock, 1898); Madagascar (A. Milne-Edwards, 1868); Mauritius ( Richters, 1880; Bouvier, 1915; Michel, 1964); Seychelles ( Richters, 1880; Bouvier, 1915; Forest & Guinot, 1961; Guinot, 1964; Michel, 1964; Serène, 1984); Pakistan ( Alcock, 1898; Khan, 1977; Tirmizi & Ghani, 1996); Saya de Malha ( Rathbun, 1911); Africa ( Lenz, 1912); Somalia ( Vatova, 1943); South Africa ( Barnard, 1950; Buitendijk, 1960; Kensley, 1981); Mayotte ( Guinot, 1958)

Persian Gulf: Persian Gulf ( Alcock, 1898; Nobili, 1906a; Chopra & Das, 1937; Stephensen, 1946)

Red Sea: Egypt ( Savigny, 1809; Audouin, 1826; Monod, 1938; Guinot & Cleva, 2009); Red Sea ( Paul’son, 1875; Kossmann, 1877; Ortmann, 1893; Nobili, 1906b; Klunzinger, 1913; Balss, 1924; Maccagno, 1936; Ramadan, 1936); Sudan ( Laurie, 1915; Pesta, 1928)

Figures

Fig. 2. Leptodius exaratus (H. Milne Edwards, 1834), neotype, male, 23.7 × 16.1 mm (NHM 1881.10), Karachi, Pakistan.A, dorsal view; B, ventral view; C, anterior view.

Fig. 4. Left G1. A–D, Leptodius exaratus (H. Milne Edwards, 1834): A, B, neotype, 23.7 × 16.1 mm (NHM 1881.10), Karachi, Pakistan; C, 23.6 × 15.5 mm (ZRC 2012.0111), Qushm, Persian Gulf; D, 21.5 × 14.2 mm (MNHN-B6640), Nosy Be, Madagascar. E–I, Leptodius affinis (De Haan, 1835): E, H, 25.9 mm × 16.6 mm, (NMST-Cr 6425), Shibasaki Hayama, Japan; F, 13.9 × 9.0 mm (ZRC 2012.0119), Con Dau, Vietnam; G, 23.9 × 15.4 mm (ZRC 2012.0110), Tranquebar, S. E. India; I, 29.5 × 19.3 mm, (ZRC 2012.0117), Negros, Philippines.