Gonatonotus pentagonus White, 1847

(Fig. 13E)

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 29, 2 ƏƏ(CB 8.4×CL 7.3 mm; 10.5× 8.4 mm, soft, deformed), 1$ (7.6× 7.5 mm), NSMT-Cr 30751. — Sta. 32, 1Ə (CB 5.1×CL 4.6 mm), NSMT-Cr 30752.

Remarks. Gonatonotus pentagonus was fully described and figured by Chia and Ng (2000), differing from two congeners, Gonatonotus granulosus (MacGilchrist, 1905) and G. nasutus Chia and Ng, 2000, in the frontal margin hardly reaching beyond the orbits. One of the specimens, a male from sta. 29, is soft-shelled and somewhat deformed, but another male (Fig. 13E) is in good condition and agrees well with the description, line drawings and photographs of many specimens, including the holotype, given by Chia and Ng (2000: figs. 16–19).

Distribution. Chia and Ng (2000) recorded many specimens from Indonesia, Singapore, Thailand and Australia, 9–54 m in depth.