Pilumnus caerulescens A. Milne-Edwards, 1873

deVries, Maaike, McGillis Hall, Linda, Dainty, Katie, Fan, Mark, Tscheng, Dorothy, Hamilton, Michael & Trbovich, Patricia, 2024, Ten Species of Crabs of the Families Acidopsidae, Aphanodactylidae and Pilumnidae (Crustacea: Decapoda: Brachyura) from the Ogasawara Islands, Japan, Bulletin of the National Museum of Nature and Science. Series A, Zoology 50 (4), pp. 155-169 : 164

Pilumnus caerulescens A. Milne-Edwards, 1873

[Jn: Nyukaredonia-kebukagani]

( Fig. 1F )

Pilumnus caerulescens A. Milne-Edwards, 1873, p. 242 , pl. 9 fig. 3. — Rathbun, 1910, p. 355, pl. 1 fig. 15; 1914, p. 660. — McNeill, 1926, p. 315. — Takeda & Miyake, 1968, pp. 6 (in key), 30, fig. 7, pl. 2 fig. D. — Garth & Kim, 1983, p. 693. — Trivedi et al., 2018, p. 60 (in list). —Takeda et al., 2023, p. 110, figs. 2, 5B.

Pilumnus forskalii coerulescens : Balss, 1933, p. 14; 1938, p. 67. ʕ Holthuis, 1953, p. 25.

Pilumnus sp. : Okuno et al., 2021, pp. 77 (in table), 82 (in discussion), figs. 3N, 4B–C.

Material examined. ɹ Chichi-jima Is. —Miyano-hama (27°06′16′′N, 142°11′39′′E), Chichi-jima I., 2–5m, 1 ˁ (cb 6.9×cl 5.2 mm), NSMT-Cr 32400, 30-VI-2014, coll. by H. Komatsu.

Haha-jima Is. ʕ Wakihama (26°38′10′′N, 142°09′29′′E), Haha-jima I., 3 ˂˂ (cb 7.3×cl 5.2 mm ʕ cb 8.2×cl 6.0 mm), 2 juvs, NSMT-Cr 32401, 7-VII-2015, coll. by H. Komatsu.

Remarks. ɹ This species is characteristic in the rough appearance of the carapace and chelipeds armed with tubercles and stiff long hairs and the carapace anterolateral margin armed with four sharp spines with stout bases ( Fig. 1F ). Takeda et al. (2023) reported this species from the Philippines and compared with Pilumnus hirsutissimus Takeda and Komatsu, 2020 , from Japan, which is similar in the hairy appearance, but different in the soft, not stiff hairs.

Pilumnus sp. from Chiba Prefecture recorded by Okuno et al. (2021) is referred to this species due to the color photograph and line drawings of the carapace and ambulatory leg.

Distribution. ɹ Mainly tropical and subtropical Indo-West Pacific waters, from the Andaman Islands eastwards to Australia and New Caledonia, and from the Gulf of Thailand northwards to Japan (Ryukyu Islands, Boso Peninsula and Ogasawara Islands) through the Micronesian islands and the Philippines.

Figures

Fig. 1. A–D: Raoulia fortis Ng and Rahayu, ˁ (NSMT-Cr 32390; cb 10.2×cl 8.2mm) from Tsuri-hama, Chichijima I. E: Viaderiana longipes (A. Milne-Edwards), young ˁ (NSMT-Cr 32405; cb 5.2×cl 4.0 mm) from Oomura Beach, Chichi-jima I. F: Pilumnus caerulescens A. Milne-Edwards, ˁ (NSMT-Cr 32400; cb 6.9×cl 5.2mm) from Miyano-hama, Chichi-jima I.