Opisthobranch of the Week Data
Dermatobranchus oculus is considered to be very rare in the waters of Okinawa's main island as I have seen and collected a total of only four individuals; the animals have been seen neither previously nor since by myself. All four were simultaneously collected on the same date and from the same locale, from beneath Tengan Pier, from an area of mixed silty-sand and oyster shell rubble during a relatively long SCUBA excursion (a 228 minute dive using twin 120cuft steel cylinders). This particular dive produced eleven lots of opisthobranchs made up of 22 individuals. This collection site is one which has been highly productive in terms of finding opisthobranchs not found elsewhere in local Okinawan waters.
Dermatobranchus oculus was previously described on these pages as Dermatobranchus sp. 4. The authors of a recent paper (Gosliner & Fahey, 2011) have now described the animal and the featured animal is the holotype*.
The following information on external morphology is taken from Fahey & Gosliner (2011):
The body shape of the living animal is elongate and narrows at the posterior end. The foot does not project beyond the distinct mantle margin. There is a series of longitudinal dorsal ridges. The oral veil extends forward and has blunt extensions at the corners. The widely spaced rhinophores are behind the oral veil. They have a series of longitudinal lamellae on the rounded club. The stalk does not narrow noticeably. There are visible marginal sacs along the mantle edge. There are no branchial or hyponotal lamellae. The genital opening is situated at the anterior quarter of the body side and the anus is situated in the anterior half. The ground colour of the dorsum and foot is opaque white. The depressions between the dorsal ridges are light grey. There are dark centered ocellated spots on the dorsum surrounded by pink pigment. The rhinophore stalk is white and the club is black. The oral veil is opaque white with a light grey border.
As of the current date (Early-April, 2014) thirteen described species of Dermatobranchus from Okinawa's main island and the Keramas are featured on these pages. These thirteen species are:
*Holotype: See "Type" Dictionary for explanation.
D. albus D. caeruleomaculatus D. cymatilis D. dendronephthyphagus D. diagonalis D. fasciatus D. fortunatus D. funiculus D. gonatophora D. oculus - The featured animal above (Holotype*) D. ornatus D. primus D. rodmani