Thalamita chaptalii (Audouin, 1826)

(Fig. 7E–F)

Material examined. Off Kuwannon, Koror Is., Palau Is., dredged, with coralline algae; 1 ♂ (cb 12.6×cl 8.2 mm), NSMT-Cr 30970; June 17, 1980, K. Baba leg. ─Entrance of Toagle Mid in Arangel Channel, Babelthuap I., Palau Is., 40 m in depth, mud; 1♂ (8.6×6.0 mm), NSMT-Cr 30971, 1♂ (12.4× 8.4mm), 1 ovig.♀ (11.7× 8.1 mm), NSMT-Cr 30972; June 22, 1980; K. Baba leg. ─ Inside of Gesodokkuru Reef off Arumonogui, Babelthuap I., Palau Is, dredged, ca. 20 m in depth; 1 ovig.♀ (11.1× 7.2mm), NSMT-Cr 30973; July 13, 1980; K. Baba leg.

Remarks. This species was briefly characterized by Wee and Ng (1995), with figures, being most characterized by the weakly arched front divided into two by a small median notch (Fig. 7E–F). The carapace dorsal ridges are also simply but clearly shown by Crosnier (1962), with a pair of the frontal, mesogastric, metagastric, epibranchial and mesobranchial ridges, but no cardiac ridge (Fig. 7E–F).

Distribution. Indo-West Pacific from the Red Sea and Madagascar to Australia, Tahiti, and the Ryukyu Islands. The occurrence in the Ryukyu Islands is referred to Nagai and Nomura (1988); the definite locality was not recorded, but the identification is acceptable for the photograph in the filed. New to the Palau Islands.