Doris tricolor (Baba, 1938)

Location: Araihama, Misaki, Kanagawa, Japan
Date: 2023/03/16
Length: 30mm
Depth: 0.1m
Water temperature: ??℃

Description

A dorid 30-40 mm in length, elongate-elliptical, the dorsum closely set with rounded tubercles. Ground colour bright chrome yellow with purplish patches along the mantle margin. The mid-dorsal region forms a purplish-white longitudinal field, externally bordered by a dark green line that grades into the chrome-yellow ground. Within this purplish-white field a broad dark-purple band runs from between the rhinophores to the branchiae, but is widely interrupted by purplish white near the middle. Tips of the dorsal tubercles dark purple. Rhinophores yellow above and white below; the five branchial plumes are tri- to quadripinnate, ashy yellow speckled with dark brown.

Distribution

Type locality: Seto, Kii Peninsula, Japan. The original description also reports the species as fairly common on the shore at Sunosaki on the Boso Peninsula.

Etymology

The Latin tricolor means "three-coloured", referring to the combination of chrome yellow (ground), purplish white (mid-dorsal field) and dark purple (longitudinal band and tubercle tips) that characterises the dorsum. The Japanese vernacular name "Sanshiki-umiushi" (literally "three-colour sea slug") was first proposed for this species in the imperial household's Opisthobranchia of Sagami Bay 1949 and reflects the same three-colour pattern.

Remarks

the 1938 monograph erected the new genus Neodoris with N. tricolor as its type species, separating it from Archidoris, Anisodoris and Doris on anatomical grounds. Baba 1998 subsequently transferred the species to Archidoris and provided an anatomical redescription, and the current combination Doris tricolor follows that reassessment.