Abstract
Two leucosiid crabs, Cryptocnemus obolus Ortmann, 1892 and Ebalia tuberculosa (A. Milne-Edwards, 1873), collected south of Jeju Island, are recorded for the first time from Korea. The identification of these new species increases the number of genera and species from the family Leucosiidae in Korean waters to 13 genera and 17 species. In this article, brief descriptions and illustrations are provided for both taxa.
Introduction
The family Leucosiidae currently contains three subfamilies: Leucosiinae Samouelle, 1819, Cryptocneminae Stimpson, 1907, and Ebaliinae Stimpson, 1871, with Philyrinae Rathbun, 1937 included in the Ebaliinae (Ng et al., 2008; Emmerson, 2016). However, the scope of leucosiid systematics is not well defined. The leucosiid crabs from Korean waters belong to 11 genera and 15 species (Lee et al., 2009).
During a faunal study on leucosiid crabs from Korean waters of the East China Sea, two species not previously recorded were found, Cryptocnemus obolus Ortmann, 1892 and Ebalia tuberculosa (A. Milne-Edwards, 1873). This is the first record of the small-sized leucosiid crabs C. obolus and E. tuberculosa in Korean waters.
The examined specimens are deposited in the National Institute of Fisheries Science (NIFS), South Korea. The terminology used here follows mainly that of Davie et al. (2015). Maximum carapace length (CL), including the rostrum, and carapace width (CW) are used measurements of the specimens.
Family Leucosiidae Samouelle, 1819 Subfamily Cryptocneminae Stimpson, 1907 Genus Cryptocnemus Stimpson, 1858 Cryptocnemus obolus Ortmann, 1892 (fig. 1) [Korean name: Dung-geun -ae-gi-bam-ge]
Cryptocnemus obolus Ortmann, 1892, female (NIFS-CR 20210510-1; 6.0 × 7.0 mm): A, entire animal, dorsal view; B, left cheliped, outer view; C-F, left 1st–4th ambulatory legs, outer view; G, pleon somites. Scale bars: A–G = 1.0 mm.
Citation: Crustaceana 94, 6 (2021) ; 10.1163/15685403-bja10139
Cryptocnemus obolus Ortmann, 1892: 576, pl. 26 fig. 12; Ihle, 1918: 286, 317 (list); Yokoya 1933: 117, text-fig. 40; Sakai, 1935: 63; 1936: 59, text-fig. 20; 1937: 140, text-fig. 25; 1965: 45, pl. 18 fig. 2; Takeda & Miyake, 1970: 228; Takeda, 1973: 29, fig. 3c; Sakai, 1976: 125, text-fig. 71, pl. 36 fig. 5; Dai et al., 1986: 89, fig. 48; Dai & Yang, 1991: 100, fig. 48 (102); Takeda, 1997: 237; 2001: 226; Chen & Sun, 2002: 458, fig. 208; Ng et al., 2008: 88; Takeda et al., 2011: 37, fig. 9; Shih et al., 2013: 729, fig. 1a.
Material examined. — South of Jeju Island, 32°48.12′N 126°16.11′E, 113 m, otter trawl, 24 April 2004, 2 females (CL 6.0 mm, CW 7.0 mm; CL 5.9 mm, CW 6.5 mm), NIFS-CR 20210510-1.
Diagnosis. — Carapace pentagonal or subcircular, gently convex dorsally; dorsal surface without spines; lateral to posterior margins lamelliform, anterior margins of hepatic region forming obtuse tooth at posterior part of hepatic region; rostrum bilobed with U-shaped median notch, gently curved upwards (fig. 1A). Chelipeds relatively stout, margins of merus, carpus and palm thinly carinated (fig. 1B). Ambulatory legs concealed below lamelliform margins of carapace when folded; meri to carpi flattened dorsoventrally, dactylus acicular, slender, long (fig. 1C–F). Female pleon rounded, somites 2–6 fused, telson subtriangular (fig. 1G).
Distribution. — Previously known from East China Sea, South China Sea, western Japan, Sulu Islands, Philippines, and Taiwan, 180-200 m depth (Sakai, 1976; Dai et al., 1986; Dai & Yang, 1991; Shih et al., 2013). Newly recorded in Korea, 113 m depth (present study).
Remarks. — The genus Cryptocnemus has 22 species (Komatsu & Takeda, 2000; Galil & Ng, 2020). Within the genus, Cryptocnemus obolus is well characterized by lateral and posterior lamelliform margins (Shih et al., 2013). The present specimen agrees well with the original and subsequent descriptions of C. obolus (cf. Ortmann, 1892; Sakai, 1937). The presence of this species also represents the first record of the genus and subfamily from Korea.
Subfamily Ebaliinae Stimpson, 1871 Genus Ebalia Leach, 1817 Ebalia tuberculosa (A. Milne-Edwards, 1873) (fig. 2) [Korean name: Ae-gi-ho-du-bam-ge]
Ebalia tuberculosa (A. Milne-Edwards, 1873), male (NIFS-CR 20210510-2; 6.5 × 6.1 mm): A, entire animal, dorsal view; B, left cheliped, outer view; C-F, left 1st–4th ambulatory legs, outer view; G, pleon somites; H, right first pleopod. Scale bars: A–G = 1.0 mm, H = 0.3 mm.
Citation: Crustaceana 94, 6 (2021) ; 10.1163/15685403-bja10139
Restricted synonymy. —
Persephona tuberculosa A. Milne Edwards, 1873: 10, 86.
Ebalia tuberculosa Miers, 1886: 305-306, pl. 25 fig. 1, 1a; Sakai, 1937: 111, text-figs. 11a–d; Takeda & Miyake, 1970: 211; Sakai, 1976: 71, fig. 33a–c; Miyake, 1983: 59, pl. 20 fig. 1; Takeda, 1997: 237; 2001: 228; Davie, 2002: 260; Ahyong, 2008: 38, fig. 17c–d (full synonymy); Ng et al., 2008: 90; Komatsu, 2011: 238, fig. 7; Takeda et al., 2011: 38, fig. 9.
Ebalia (Ebalia) tuberculosa Griffin, 1972: 57.
Material examined. — South of Jeju Island, 32°48.12′N 126°16.11′E, 113 m, otter trawl, 24 April 2004, 1 male (CL 6.5 mm, CW 6.1 mm), NIFS-CR 20210510-2.
Diagnosis. — Carapace as long as broad, slightly subhexagonal or subcircular; dorsal surface strongly convex dorsally, regions clearly demarcated by deep grooves, surface generally covered with thickened granules, 5 large tubercles present on upper surface; posterior margin armed with median tubercle and posterolateral tubercles on each side; hepatic regions obtuse, swollen; rostrum separated by deep median notch, slightly convex (fig. 2A). Chelipeds long, slender, covered with flat-topped granules; less than twice carapace length; fingers shorter than palm (fig. 2B). Ambulatory legs except dactyli covered with thickened tubercles; dactylus almost smooth, slender (fig. 2C–F). Male pleon triangular, somites 3–5 fused, telson elongated triangular (fig. 2G). First pleopod of male slender, with tip gradually tapering to distal end (fig. 2H).
Distribution. — This species is widely distributed in the Indo–West–Central Pacific from South Africa to Japan, east to Hawaii, and south to New Zealand; 50–550 m depth (Takeda, 2001; Davie, 2002; Komatsu, 2011). Newly recorded in Korea, 113 m depth (present study).
Remarks. — The genus Ebalia includes more than 80 species (Naruse & Ng, 2006; Komatsu & Takeda, 2007; Komatsu, 2011); but its taxonomy is far from stable. Ebalia tuberculosa is characterized by sexual dimorphism, which has been the most significant source of morphological variations (Ahyong, 2008). Although the present collection includes only one male specimen, its morphology agrees well with the descriptions of E. tuberculosa by Sakai (1937) and Barnard (1947), except that in the present specimen, the carapace and the appendages are covered with flat-topped granules, whereas Sakai (1937) and Barnard (1947) recorded numerous conical or sharp granules. This is recorded as variation for the time being (see Barnard, 1947: 364, fig. 70).
Corresponding author; e-mail: choi2291@korea.kr
Acknowledgement
This work was supported by a grant from the National Institute of Fisheries Science, South Korea (R2021035).
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