Rectopalicus ampullatus Castro, 2000

(Fig. 2A)

Rectopalicus ampullatus Castro 2000: 535 (in key), 541, figs. 36, 37a, b.— Marumura & Kosaka 2003: 71 (in list), fig. 24.— Marumura & Takeda 2009: 78, fig. 6.

Material examined. R/V Tansei Maru (Ocean Research Institute, The University of Tokyo) KT-97-7 cruise, sta. CC-04 (27° 0 7.963'N, 142° 0 6.732'E— 27° 0 7.735'N, 142° 0 6.832'E, 156-157 m), west of Ani-jima I., Ogasawara Is.; 1 female (cb 6.8 mm, cl 6.7 mm), 1 juvenile (cb 6.7 mm, cl 6.5 mm), NSMT-Cr 22986; June 8, 1997.

Remarks. Both chelipeds are missing in the female examined and all the legs are detached in the juvenile specimen. The specimens can be identified because of the characteristic appearance of the carapace, with laterally and dorsally inflated branchial regions (Fig. 2A) differing from the other congeneric species, Rectopalicus amphiceros Castro, 2000 and R. woodmasoni (Alcock, 1900) . Following Castro (2000), Palicus microfrons Sakai, 1963 is now considered a junior synonym of R. woodmasoni . In Japanese waters, R. woodmasoni has been recorded as Palicus microfrons Sakai, 1963 by Sakai (1963, 1965, 1976) and Palicoides microfrons by Takeda (1982).

Distribution. This species was originally reported from the Loyalty and Futuna islands in the southwestern Pacific Ocean at a depth of 200-300 m (Castro 2000). It is also known from southeast off Kume-jima Island in the central Ryukyu Islands at the depth of 250 m (Marumura & Kosaka 2003; Marumura & Takeda 2009). The distributional range is now extended to the Ogasawara Islands.