Leptodius affinis (De Haan, 1835)

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 : 192-196

Leptodius affinis (De Haan, 1835)

( Figs. 3 , 4E–I )

Cancer (Xantho) affinis De Haan, 1835: 48 , pl. 13 fig. 8 [ Japan]; Krauss, 1843: 30 [ Japan]

Cancer (Xantho) lividus De Haan, 1835: 48 , pl. 13 fig. 6 [ Japan] [not Cancer lividus Latreille , in Milbert, 1812].

Chlorodius exaratus, Dana, 1852: 208 [Pacific] [not Chlorodius exaratus H. Milne Edwards, 1834 ]

Leptodius exaratus , A. Milne-Edwards, 1873: 222 [ New Caledonia]; Miers, 1879: 31 [ Korea and Japan]; Haswell, 1882: 60 [ Australia]; De Man, 1887a: 33 [Mergui Archipelago]; 1887b: 285 [Nordwachter Island, Java Sea]; 1892: 278 [Sulawesi]; Alcock & Anderson, 1894: 200 [Bay of Bengal, Laccadive Sea]; Balss, 1922: 127 [ Japan]; Shen, 1932: figs. 57, 58c, d; 1937: 307 (list) [northern China]; Yokoya, 1933: 189 [ Japan]; Sakai, 1934: 309; 1936: 151, pl. 45, fig. 3; 1965: 140, pl. 70, fig. 6; 1976: 423, pl. 153, fig. 1 [ Japan]; Chopra & Das, 1937: 398 (in part) [Bay of Bengal, Mergui Archipelago]; Sankarankutty, 1962: 129 [Andaman Is.]; 1966: 351 [ Sri Lanka]; Kim, 1970: 14 [ Korea]; 1973: 380, fig. 144, pl. 82, fig. 109 [ Korea]; Takeda & Nunomura, 1976: 70 [ New Caledonia]; Takeda, 1976: 74 [ Palau]; 1978: 39 [Amakusa, Japan]; Takeda & Miyake, 1976: 109 [Ogasawara, Japan]; Yamaguchi et al., 1976: 37 [Amakusa, Japan]; Garth & Kim, 1983: 570 [ Philippines]; Dai et al., 1986: 271, figs. 154(3), 155A(1), pl. 37(4), 37(5) [ China]; Dai & Yang, 1991: 292, pl. 37(4), fig. 154(3) [ China]; Yamaguchi & Baba, 1993: 446, figs. 164A, B [ Japan]; Jones & Morgan, 1994: 166, 167, with figure [ Australia]; Minemizu, 2000: 260, with figure [ Japan]; Davie, 2002: 550–551 [ Australia]; Ng & Davie, 2002: 374 [ Thailand]; Paulay et al., 2003: 504 [Marianas]; Poore, 2004: 472, fig. 150b [ Australia]; Davie, 2011: 233, with figure [ Australia][not Chlorodius exaratus H. Milne Edwards, 1834 ]

Xantho exaratus var. typica Ortmann, 1893: 445 (in part) [ Samoa; Japan; Fiji; Caroline Is.; Australia] [not Chlorodius exaratus H. Milne Edwards, 1834 ]

Chlorodius exaratus var. pictus Stimpson, 1907: 54 , fig. 6 [Simoda, Japan] [not Chlorodius exaratus H. Milne Edwards, 1834 ]

Chlorodius exaratus var. typicus Stimpson, 1907: 55 [ China; Japan] [not Chlorodius exaratus H. Milne Edwards, 1834 ].

Xantho (Leptodius) exaratus, Alcock, 1898: 118 [353] (in part) [Mergui,Andamans, Sri Lanka, Burma, Malaysia]; Laurie, 1906: 402 [ Sri Lanka]; Gravely, 1927: 146 [Gulf of Mannar]; Gordon, 1931:528, 543, fig. 22b; 1934: fig. 16b [ China]; Boone, 1934: 110, pl. 58 [ Australia, French Polynesia]; Balss, 1935: 133 [SW Australia]; 1938: 41 [ Nauru, Marshall Is.]; Estampador, 1937: 525; 1959: 79 [ Philippines]; Sakai, 1939: 464, pl. 58, fig. 3, pl. 91 [ Japan]; Miyake, 1939: 209; 1940: 155 [ Micronesia]; Chang, 1963: 99 [ Taiwan]; McNeill, 1968: 58 [ Australia] [not Chlorodius exaratus H. Milne Edwards, 1834 ]

Xantho exaratus, Holthuis, 1953: 27 [Gilbert Is.; Tuamotu Archipelago]; Buitendijk, 1960: 331, fig. 9 k–m (in part) [ Indonesia; China; Fiji; Japan; Myanmar; Philippines; Samoa; Society Is.; Thailand] [not Chlorodius exaratus H. Milne Edwards, 1834 ]

Leptodius nigromaculatus Serène, 1962: 255 , figs. 1A–H; 1984: 182 (key) [ Vietnam]; Dai et al., 1986: 272, fig. 155A [ China]; Dai & Yang, 1991: 293, pl. 37(5), fig. 155A [ China]; Yeh et al., 2006: 70, figs. 1C, F, 2C–D [ Taiwan]

Type locality. — Japan (De Haan, 1835: 48) .

Material examined. — Australia – 2 males (21.1 × 13.8 mm; ZRC 2012.0112 ), (23.4 × 15.1 mm; ZRC 2012.0113 ), Ningaloo Reef , Western Australia, R. Lasley coll., 19 May 2010 . China – 1 male (32.5 × 20.0 mm; ZRC 2012.0114 ) , 3 males (13.0 × 8.5 mm – 23.5 × 15.0 mm; ZRC 1998.542 ), Changpo, Hong Kong , coll. P. K. L. Ng & S. Y. Lee, 6 Jun.1998 ; 2 males (30.2 × 18.6 mm, 30.7 × 19.0 mm; ZRC 1999.0625 ) , 1 female (22.8 × 14.1 mm; ZRC 1999.0458 ), Nanao Is., Guangdong, coll. Y. Cai & N. K. Ng, 13 Nov.1998 ; 2 males (15.4 × 10.0 mm, 19.6 × 13.1 mm), 1 female (14.2 × 9.3 mm; ZRC 2012.0115 ), Hainan Is. , coll. Y. Cai & N. K. Ng, 1 Dec. 1998 ; 2 males (17.0 × 11.6 mm, 13.2 × 8.1 mm), 2 females, (23.1 × 13.5 mm, 18.0 × 11.8 mm; ZRC 2010.0352 ), Shi Jing Village , Xiamen County, Fujian Province, coll. Z. Jaafar & N. K. Ng, 17 Nov.2005 . Eastern India – 1 male (23.9 × 15.4 mm; ZRC 2012.0110 ), Tranquebar , Tamil Nadu, coll. N. K. Ng, B. Y. Lee & R. M. Lasley, Nov.2011 . Indonesia – 1 female (15.8 × 10.3 mm; ( ZRC 1999.1203 ), Bintan Is., coll. Riau, J. B. Sigurdsson, 27 Mar.1993 ; 1 female (13.9 × 9.5 mm; ZRC 2003.0548 ), Anambas Is. , stn EA-2jc7, 15 Mar.2002 . Japan – 1 male (25.9 × 16.6 mm) , 1 female (16.1 × 10. 6 mm; NMST-Cr 6425), Shibasaki Hayama , Kanagawa, coll. M. Takeda, 25 Jul.1980 ; 2 males (23.7 × 15.2 mm, 29.4 × 19.0 mm), 1 female (21.2 × 13.5 mm; CBM-ZC 143 ) , 2 males (12.9 × 8.6 mm, 35.0 × 21.7 mm), 1 female (20.3 × 13.3 mm; CBM-ZC 559 ), Ogasawara Is .; 1 female (22.6 × 14.2 mm; ZRC 2009.0145 ), Iriomote Is., Yaeyama Group, southern Ryukyu Islands , coll. N. K. Ng, 16 Jun.2000 ; 2 males (14.6 × 9.2 mm, 23.3 × 15.0 mm; ZRC 2011.0170 ), Amakusa, Kyushu , J. C. Y. Lai coll., 3 Apr.2011 . Korea – 2 males (32.0 × 20.3 mm, 36.8 × 23.2 mm; MADBK 173012 _011), Iho-ri , Jejudo Is., coll. H. S. Kim, 11 Aug.1969 ; 3 male (19.7 × 12.7 mm – 30.6 × 19.3 mm; MADBK 173012 _012), Sindo-ri , Jejudo Is., coll. S. K. Lee 25 Oct.2005 ; 1 male (15.7 × 10.4 mm; MADBK 173012 _013), Aewel-eup, Jejudo Is. , coll. S. K. Lee, 16 Oct.2006 ; 2 males (20.5 × 13.2 mm, 23.1 × 14.7 mm; MADBK 173012 _014), Jo-1ri, Udo Is., Jejudo, coll. S. K. Lee, 14 Dec.2006 . Malaysia – 1 male (19.4 × 12.6 mm; ZRC 1991.461 ), Pulau Tioman , coll. P. K. L. Ng, 30 Mar.1982 ; 1 male, (26.4 × 16.0 mm), 3 females (13.6 × 8.9 mm – 16.8 × 11.3 mm; ZRC 1985.1722 - 1725 ), Tanjong Bidara , Malacca, coll. P. K. L. Ng, 16 Feb.1985 . New Caledonia – 2 males (15.8 × 10.5 mm, 17.0 × 11.4 mm) , 2 females (18.3 × 12.8 mm, 17.4 × 11.4 mm; MNHN-B8631 ), coll. Balansa, no date . Philippines – 2 males (23.5 × 15.6 mm, 27.7 × 18.0 mm) , 1 female (21.8 × 14.1 mm; ZRC 2012.0116 ) , 8 males (13.6 × 9.0 mm – 29.5 × 19.3 mm), 2 females (12.6 × 8.4 mm, 23.8 × 15.5 mm; with sacculinid; ZRC 2012.0117 ), Punta Taytay , Bacolod, Negros Is., coll. J. C. E. Mendoza, 27–28 Dec.2011 . Singapore – 7 males (12.0 × 7.6 mm – 31.0 × 20.2 mm; ZRC 2012.1232 ), Changi Beach Park, Singapore, 4 May 2012 ; 2 males (24.7 × 15.0 mm, 27.1 × 17.0 mm), 2 females (21.0 × 13.5 mm, 22.8 × 14.5 mm; ZRC 1993.33 - 51 ), Labrador Beach, Jan.1987 ; 3 males (19.0 × 12.1 mm – 22.7 × 14.0 mm; ZRC 1995.339 ), Semakau , coll. P. K. L. Ng, 8 Feb.1993 ; 3 males (23.6 × 15.0 mm – 29.0 × 18.3 mm; ZRC 2000.1197 ), Pulau Seringat , coll. C. M. Yang & S. L. Goh, 22 Jul.1997 . Taiwan – 1 male (29.3 × 18.5 mm; ZRC 1995.620 ), Shihmen , Taipei, coll. C. H. Wang, 24 May 1987 ; 1 male (29.2 × 18.2 mm; ZRC 1999.0590 ) , 5 males (18.9 × 12.1 mm – 26.3 × 16.5 mm), 2 females (18.8 × 12.1 mm, 22.1 × 14.1 mm; ZRC 1999.0591 ), Keelung, Magang , coll. H. H. Tan, 3 Aug.1996 ; 2 males (29.0 × 18.5 mm, 23.0 × 15.1 mm; ZRC 1999.0581 ), He Ping Tao , coll. Keelung, H. H. Tan, 4 Aug.1996 . Thailand – 9 males (14.8 × 9.7 mm – 24.5 × 15.5 mm) , 4 females (13.0 × 8.4 mm – 16.7 × 11.2 mm; ZRC 2000.1034 ), Cape Panwa , Phuket, coll. H. H. Tan, 17 Jan.2000 ; 1 male (19.3 × 12.5 mm; ZRC 2001.1076 ), Phuket, coll. P. K. L. Ng, 17 Feb.2001 . Vanuatu – 1 male (17.9 × 11.8 mm; ZRC 2012.1233 ), stn. H6, rocky intertidal area near wharf of Vanuatu Maritime College, Luganville, Espiritu Santo, coll. P. Clark, 17 Sep.2006 . Vietnam – 2 males (12.7 × 8.4 mm, 22.4 × 14.0 mm) , 2 females (18.7 × 12.3 mm, 28.7 × 17.9 mm; ZRC 2012.0118 ), Con Dau Is. , coll. H. H. Tan et al., 12 Apr.2010 ; 8 males (9.8 × 6.3 mm – 13.9 × 9.0 mm), 13 females (6.4 × 4.2 mm – 12.8 × 8.6 mm; ZRC 2012.0119 ), Con Dau Is., 14 Apr.2010 .

Description. — Carapace ( Fig. 3A ) transversely subovate, about 1.4–1.6 times as broad as long; dorsal surface depressed, finely granular, anterior, lateral regions varying from distinctly to faintly rugose; regions well defined, separated by narrow, shallow grooves; 2F separated by groove from 1M; 2M partly divided longitudinally, 1M fused to inner branch of 2M; 3M, 2L, 3L, 4L, 5L, 6L distinct, entire; 4M indistinct; 1L very small; 1R, 2R fused, separated from 3R by indistinct oblique groove; 1P, 2P indistinct. Front about 0.3 times as broad as carapace breadth, not much protruded, cut into 2 lobes, each one slightly concave near outer side, separated from internal orbital tooth by notch. Orbit smaller, transverse oval; superior margin with 2 fissures; inferior margin bearing 2 blunt teeth on either side; exorbital angle separated from first anterolateral tooth by concavity. Anterolateral margin with 4 lobes behind exorbital angle: first small, almost indistinguishable, depressed; second broad, large; third similar, more prominent than second; last smallest but most produced; separation between teeth indicated by small sinus. Posterolateral margin somewhat concave, with pubescence. Posterior margin granular, central region straight. Pterygostomian region granular, setose.

Antennules ( Fig. 3C ) lying transversely, slightly obliquely. Basal article of antenna sub-rhomboidal, short, broad. Antennular flagellum occupied orbit hiatus. Epistome narrow; central region with median projection, separated from lateral regions by distinct notches. Third maxilliped completely filled buccal orifice; merus subquadrate, granular, anterolateral angle slightly produced, anterior margin with wide V-shape notch medially; ischium subrectangular with submedian sulcus, smooth to punctuate; exopod stout, length about 4 times width.

Thoracic sternum ( Fig. 3B ) 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, slightly convex; sternites 5–8 distinct, separate, within not visible externally. Median longitudinal line visible externally only on central 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. 3A ) asymmetrical, with a granular coating single ended, more or less curved and pointed. Merus with long setae on anterior and posterior borders, covered with fine corrugation on dorsal surface. Carpus covered with microscopic granules and fine corrugation on outer surface; inner-distal angle bluntly round. Fingers black coloured, with somewhat gaping between them closed, with distinctly toothed and contiguous within; inner margins provided with obtuse teeth, tips spoon-shaped with bristles.

Ambulatory legs ( Fig. 3A ) smooth; meri of first to third with setae on anterior and posterior margin; carpi, propodi subequal in length, sparsely setose; dactyli densely covered with short hairs, chitinous claw.

Male abdomen ( Fig. 3B ) narrow and long; somites 3–5 fused, sutures vaguely discernible; somite 6, 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. 4E–I ) slender, long, with 5 or 6 stout, curved subdistal spines; elongated apical lobe bordered on ventral margin by 5 or 6 mushroom-shaped outgrowths proximally and in distal half with 6–8 tongue-shaped outgrowths, simple, pointed, diminishing gradually near tip. Length of apical lobe measured from tip to subdistal region 0.11–0.14 times to total length; angle formed between apical lobe and rest of structure relatively G1 more bent. G2 about quarter length of G1.

Remarks. — De Haan (1835) described two species, Cancer (Xantho) affinis and C. (X.) lividus , from Japan. These two names were both simultaneously synonymised under Xantho exaratus (H. Milne Edwards, 1834) var. typica by Ortmann (1893: 445) (see also Yamaguchi & Baba, 1993). The type material for these two names is still extant: the lectotype (RMNH D 44644) and paralectotypes (RMNH D 42334, RMNH D 42335, RMNH D 44646) of Cancer (Xantho) affinis De Haan, 1835 , as well as the lectotype (RMNH D 42333) and paralectotype (RMNH D 42336) of Cancer (Xantho) lividus De Haan, 1835 , are all deposited at the Nationaal Natuurhistorisch Museum at Leiden, The Netherlands, and have been well documented by Yamaguchi & Baba (1993: 446, fig. 164A, B) and Fransen et al. (1997: 116). Stimpson (1907) noted the morphological variations among different populations of L. exaratus in the Pacific region, and established varieties within this species to distinguish these populations. Serène (1962) described another species, Leptodius nigromaculatus , from southern Vietnam, which he thought to be more closely allied to L. gracilis ( Dana, 1852) , perhaps due to the less rugose carapace and less projecting anterolateral teeth. The holotype of L. nigromaculatus could not be located; it has not been found in the MNHN, despite several attempts, and it may still be in Serène’s former institution in Nhatrang, Vietnam. Several topotypic specimens from southern Vietnam were examined instead in order to confirm the synonymy. Besides these, the literature is rife with several records of “ Leptodius exaratus ”, or variants thereof, from the western Pacific and eastern Indian Ocean.

Based on differences in G1 morphology, however, it is clear that these records are not of L. exaratus s. str. Both L. exaratus s. str. and the similar L. affinis (De Haan, 1835) have a broad, transversely subovate carapace, which has four broadly triangular anterolateral teeth, a rugose dorsal surface and well-defined regions. There is much variability and overlap in the carapace morphology within each species. Features of the mouthparts, thoracic sternum, abdomen and pereopods are also not useful, and morphometric analyses of the carapace and thoracic sternum ( Fig. 5A, B ) reveal no significant difference between the two species.

The main difference between L. exaratus s. str. and L. affinis can be seen in the G1 morphology ( Figs. 4 , 5C ), where: 1) the apical lobe is proportionally shorter in L. exaratus than in L. affinis ; 2) it is also more tightly curled, nearly a closed cylinder (vs. more open and expanded in L. affinis ); 3) the angle formed between the apical lobe and the rest of the G1 is larger (vs. less in L. affinis , giving it a more bent appearance); and 4) the ventral lip of the apical lobe has fewer outgrowths in L. exaratus than in L. affinis (for L. exaratus see Forest & Guinot, 1961: 62, fig. 54; Serène, 1984: 180, fig. 106; for L. affinis see Serène, 1962: 258, fig. 1; Yeh et al., 2006: 73, fig. 2C, D).

The following discussion in this paper shows that these records refer to L. affinis (De Haan, 1835) , and that at least some of the various synonyms in the literature are justified. Concerning records of “ L. exaratus ” from the Hawaiian islands in the central Pacific (viz. Stimpson, 1858 ; Rathbun, 1906; Edmondson, 1925, 1946, 1962; Titgen, 1987; Castro, 2011), it is clear after examining the published figures and material collected from there that these are not L. exaratus or L. affinis as defined at present, and belong to other species. They will be treated and discussed elsewhere.

Distribution. — Leptodius affinis (De Haan, 1835) is found in the eastern Indian Ocean and in the western and central Pacific Ocean, ranging from the eastern coast of India all the way to the oceanic islands of French Polynesia; extending northward to central Japan and southward to southwestern and southeastern Australia. It has been recorded from the following localities:

Eastern Indian Ocean: Mergui Archipelago (De Man, 1887a; Alcock, 1898; Chopra & Das, 1937); Bay of Bengal (Alcock & Anderson, 1894; Chopra & Das, 1937); Laccadive Sea (Alcock & Anderson, 1894); Andamans ( Alcock, 1898; Sankarankutty, 1962); Gulf of Mannar ( Gravely, 1927); Myanmar ( Alcock, 1898; Buitendijk, 1960); Penang ( Alcock, 1898); Sri Lanka ( Alcock, 1898; Laurie, 1906; Sankarankutty, 1966); western Thailand ( Ng & Davie, 2002).

Western Pacific: Japan (De Haan, 1835; Krauss, 1843; Miers, 1879; Ortman, 1893; Stimpson, 1907 ; Balss, 1922; Yokoya, 1933; Sakai, 1934, 1936, 1939, 1965, 1976; Takeda & Miyake, 1976; Yamaguchi et al., 1976; Takeda, 1978; Yamaguchi & Baba, 1993; Minemizu, 2000); Australia ( Haswell, 1882; Ortmann, 1893; Boone, 1934; Balss, 1935; McNeill, 1968; Jones & Morgan, 1994; Davie, 2002, 2011; Poore, 2004); Korea ( Miers, 1879; Kim, 1970, 1973); Indonesia (De Man, 1892; Buitendijk, 1960); China ( Stimpson, 1907 ; Gordon, 1931; Shen, 1932, 1937; Dai et al., 1986; Dai & Yang, 1991); Hong Kong ( Stimpson, 1907 ); Philippines ( Estampador, 1937, 1959; Buitendijk, 1960; Garth & Kim, 1983); Micronesia ( Miyake, 1939, 1940); Gilbert Is. ( Holthuis, 1953); Thailand ( Buitendijk, 1960); Vietnam ( Serène, 1962); Taiwan ( Chang, 1963; Yeh et al., 2006).

Central Pacific: Pacific ( Dana, 1852); Samoa, Fiji, Caroline Is. ( Ortmann, 1893; Buitendijk, 1960); Nauru, Marshall Is. ( Balss, 1938); Tuamotu Archipelago ( Holthuis, 1953); Palau (Takeda, 1976); Marianas ( Paulay et al., 2003).

South Pacific: New Caledonia (A. Milne-Edwards, 1873; Takeda & Nunomura, 1976); French Polynesia ( Boone, 1934).

Figures

Fig. 3. Leptodius affinis (De Haan, 1835), male, 25.9 × 16.6 mm (NSMT-Cr6425), Shibasaki, Kanagawa, Japan. 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.

Fig. 5. Results of morphometric analysis of Leptodius exaratus (H. Milne Edwards, 1834) (A–C: n= 28) and L. affinis (De Haan, 1835) (A, B: n = 99; C: n = 64). Box plots depicting maxima, minima, median, and quartile values for: A, ratios of the sternite 4 width and combined length of sternites 3 and 4; B, ratios of the frontal and carapace widths; C, ratios of the apical lobe length and total length of the G1.