Nanopilumnus heterodon

Nanopilumnus heterodon (Sakai, 1934) [Jn: Kawari-kebukagani] (Fig. 4D–E) Pilumnus heterodon Sakai, 1934, p. 307, fig. 19; 1976, pp. 484 (in key), 488 (English vol.), p. 301 (Japanese vol.), fig. 262a, pl. 174 fig. 3. — Sankarankutty, 1962, p. 114, figs. 48–50. — Muraoka, 1998, p. 44. — Takeda & Manuel, 2000, p. 159, fig. 4B. — Kato & Okuno, 2001, p. 131, 1 unnumbered fig. Pilumnus barbatus A. Milne-Edwards, 1873: Balss, 1938, p. 57. — Sakai, 1939, p. 538. — Takeda & Miyake, 1968, p. 9, figs. 1d–f, 2. Nanopilumnus heterodon: Ng et al., 2008, p. 141 (in list). — Trivedi et al., 2018, p. 60 (in list). Material examined. ɹ Chichi-jima Is. —Omura Beach (27°05′35′′N, 142°11′38′′E), Chichi-jima I., 12 m, 1 ˁ (cb 7.9×cl 5.7 mm), NSMT-Cr 32394, 13-XI-2013, coll. by H. Komatsu. Remarks. ɹ This small species is characterized by the club-shaped hairs of filthy appearance covering the carapace, chelipeds and ambulatory legs; the hairs are variable in length, but basically separated into short and long types. As shown in Fig. 4D–E, of three anterolateral teeth of the carapace behind the external orbital tooth, the first two are prominent and elongate, each with a minute horny tip, protruding from the hairs; the first originates from behind the outer part of the supraorbital margin, directing anterolaterally; the second is similar to the first in size and shape, but directed more anteriorly and weakly curving forwards; the third is small, acute at tip, and disguised by the hairs. The differences of the carapace anterolateral armature of this species and the close relative, N. barbatus (A. Milne-Edwards, 1873), were illustrated by Sakai (1976). Distribution. ɹ Known from Japan, the Philippines, Singapore and the Palau Islands in the West Pacific Ocean, and the Nicobar Islands in the eastern Indian Ocean.