Opisthobranch of the Week Data
Dermatobranchus funiculus is considered to be rare on Okinawa as I have seen and collected a total of six individuals (five simultaneously from the same date and location and another on 18 Oct '94) from beneath Tengan Pier. The above featured animal is one of five collected on the ninth of July, 1991 from 40 feet of water between the hours of 0915 ~ 1215. The five animals were found in fairly close proximity to each other crawling on the surface of silty-sand and strewn oyster shell rubble. The authors of a recent paper (Gosliner & Fahey, 2011) have now described the species and the above featured animal is one of several designated paratype* specimens. I've also added a second page w/ an image of the animal collected on the eighteenth of October, 1994 and a single image of the five animals collected on the ninth of July 1991.
Dermatobranchus funiculus is also depicted in Gosliner, Behrens & Valdés, 2008 (p. 311, as Dermatobranchus sp. 16, p.314, as Dermatobranchus sp. 18, and p. 315 as Dermatobranchus sp. 21). In addition there are two images of the species in Coleman (2008): p. 122, as purple spots Dermatobranchus and p. 123 as Milne Bay Dermatobranchus.
I've frequently seen 15 plus species of opisthobranchs in the general "under-pier" area of Tengan. Possibly the great numbers of opisthobranchs found at this locality are due to the dense colonies of bryozoans, cnidarians, poriferans, and others, covering the pier pilings and pier-related materials beneath the pier. It should also perhaps be pointed out that I've frequently exceeded 200 minutes of dive time, which may, at least in part, explain the high numbers of 'branchs frequently seen here.
The following information on external morphology is taken from Fahey & Gosliner (2011):
External morphology: The body shape of the living animal is elongate, flattened, and narrows at the posterior end. The dorsal ridges are nearly parallel along the midline, but angle towards the mantle margin along the sides of the notum. The foot does not project beyond the distinct mantle margin. There is a series of 12-23 longitudinal dorsal ridges. The oral veil extends forward and has blunt extensions at the corners. The wide-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. The genital opening is on the right side of the anterior quarter of the body. The anus is situated approximately one third of the way to the posterior end of the body. There are no branchial or hyponotal lamellae under the mantle margin. The ground colour of the dorsum and dorsal ridges is white to bluish or orange. The oral veil and the foot are opaque white with an orange frontal margin. The depressions between the dorsal ridges are light grey or orange with dark dots. There are dark bands of colour across the notum, beginning approximately halfway from the anterior end. Along the mantle edge are evenly spaced, dark spots of colour. The mantle has a pinkish-orange border. The rhinophore stalk is white and the club is dark brown with opaque white to cream lamellae and apex.
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:
D. albus D. caeruleomaculatus D. cymatilis D. dendronephthyphagus D. diagonalis D. fasciatus D. fortunatus D. funiculus - The featured animal above D. gonatophora D. oculus D. ornatus D. primus D. rodmani
* Paratype: See "Type" Dictionary for explanation.