Diaphorodoris mitsuii
(Baba, 1938)

Order: NUDIBRANCHIA
Suborder: DORIDINA
Superfamily: ANADORIDOIDEA
Family: Onchidorididae

DISTRIBUTION

Japan and Hong Kong.

PHOTO

PHOTO: A. Hong Kong, April 1983, AM C139205. B. Ping Chau (S), Mirs Bay, 4-10 m. 20 April 1983, AM C139187. C. showing prominent median ridge on posterior foot. Hong Kong, April 1983, AM C139205. D. 5 specimens, Round Is. (W), Mirs Bay, 3-6 m. 14 April 1983, AM C139186. PHOTOS: B.E. Picton.

The mantle is ovate with the posterior end of the foot extending behind the end of the mantle. A distinctive feature is the distinct middorsal ridge on the posterior end of the foot. The mantle has small tubercles and the five or six gills are attached in a common pocket. Diaphorodoris mitsuii was originally recorded from southern Japan but the few specimens reported from there have been bright yellow with a submarginal orange-red band on the mantle and the foot. The gills and rhinophores are yellow. A few specimens with this yellow colour form have been found in Hong Kong but the most common form has a white body with the submarginal orange-red band and a bright yellow band at the edge of both the mantle and the foot. The gills and rhinophores are white.

One white specimen also has a yellow line, bordered with red, on the median ridge of the foot and the rhinophore lamellae are red. These all appear to be colour varieties of the one species. This species grows to about 8 mm long and most probably feeds on encrusting colonial bryozoans.

• Rudman, W.B. & Darvell, B.W. (1990) Opisthobranch molluscs of Hong Kong. Part 1. Goniodorididae, Onchidorididae, Triophidae, Gymnodorididae, Chromodorididae, (Nudibranchia). Asian Marine Biology, 7: 31-79

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