Opisthobranch of the Week Data
Dermatobranchus caeruleomaculatus is considered to be very rare in okinawan waters as I'm not aware of any animals, either photographs or specimens, taken from the waters of Okinawa's main island. Also, Atsushi Ono reports (pers. comm.) seeing only the above featured animal in the Keramas* and Atsushi's photograph is used here with his kind permission.
The following description of external morphology is taken from the Gosliner and Fahey (2011) publication:
The body shape of the living animal is elongate, but broad, slightly flattened, and narrows at the posterior end. The foot does not project beyond the distinct mantle margin. The dorsum has approximately 24 well-elevated, longitudinal ridges on either side of the midline that may further divide posteriorly. The oral veil is large and expansive with slightly pointed corners. The well separated, bulbous rhinophores are situated behind the oral veil. They have a series of longitudinal lamellae on the rounded club, which has a small rounded apex. The stalk does not narrow noticeably. Marginal sacs are readily visible along the mantle edge.
There are no hyponotal or branchial lamellae under the mantle margin. The genital opening is situated in the anterior quarter of the body. The anus is situated approximately half of the way to the posterior end of the body.
The ground colour of the dorsum is white with a series of brown spots arranged in longitudinal lines along the margin of the ridges. The oral veil and the margin of the notum have a series of blue spots, each with a black centre. There are also fine brown spots on the posterior end of the oral veil. There is a marginal yellow-orange band on both the notum and the oral veil. The rhinophore stalk is white with brown spots and the club is dark brown to black with opaque white pigment on the lamellae. The tip of the rhinophores is white.
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 - The above featured animal D. cymatilis D. dendronephthyphagus D. diagonalis D. fasciatus D. fortunatus D. funiculus D. gonatophora D. oculus D. ornatus D. primus D. rodmani
* Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.