Nanopilumnus heterodon ( Sakai, 1934 )

Nanopilumnus heterodon ( Sakai, 1934) View in CoL [Jn: Kawari-kebukagani]

( Fig. 4D–E View Fig )

Pilumnus heterodon Sakai, 1934, p. 307 View in CoL , 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 View in CoL : Balss, 1938, p. 57. — Sakai, 1939, p. 538. — Takeda & Miyake, 1968, p. 9, figs. 1d–f, 2.

Nanopilumnus heterodon View in CoL : 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 View Fig , 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.