Palio amakusana Baba, 1960

Location: Yudou, Minamata, Kumamoto, Japan
Date: 2018/03/21
Length: 30mm
Depth: 7.0m
Water temperature: 13.0℃

Description

A polycerid 12-20 mm in length. With 4-6 exo-branchial appendages on each side, slightly larger than those on the back-margins. Velum-margin papillae 12-14. Back, sides and tail covered with small conical papillae. Rhinophores non-retractile; 5 tripinnate non-retractile gills; oral tentacles lobiform; foot-corners angulated. General body-colour yellowish brown, somewhat darker on back and sides. Rhinophores bright orange above, yellow at tip. Gills yellowish brown. Exo-branchial appendages white; other papillae on the pallial margin and on the integument also whitish. Sole yellowish brown.

Distribution

Type locality: Tomioka, Amakusa (Kumamoto Pref., Japan); type material also from Abugashima, Toyama Bay. At the time of description, recorded only from Amakusa; later records also from Toyama Bay.

Etymology

The specific epithet amakusana is an adjective from the type locality (Amakusa), formed with the Latin adjectival suffix -ana.

Remarks

The genus Palio was first recorded from Japan in the paper that described this species. The diagnostic absence of a jaw-plate wing (triangular jaw plates without a wing) places it in Palio. Closely similar in body form, jaws and radula to the Atlantic and Mediterranean Palio dubia (= P. tessonii), but separated by colour details (yellowish brown body, bright orange rhinophores, white appendages).