Opisthobranch of the Week Data
The above featured animal is one which was photographed in the waters of Amuro Island, one of a series of islands in the Kerama Islands Group, which are located 30 ~ 40 kilometers west of the Okinawa capitol, Naha. The animal was photographed by Atsushi Ono during July of 1998, as it was rapidly crawling on the surface of sand. Atsushi's photograph is used here with his kind permission and he considers the species to be rare; Atsushi reports (pers. comm.) seeing only three uncollected individuals in the Keramas. I've been looking for this beautifully patterned animal here for quite a few years without success. The only specimen I know of from Okinawa's main island, was collected and turned in as a preserved 31mm specimen by an undergraduate student as part of a required marine invertebrate biology collection.
The following description of P. pilsbryi is taken from Marshall & Willan (1999):
This is a large cephalaspidean which has a broad body. The head shield is approximately equal to the posterior shield in length and its posterior margin is not raised. There is a distinct lump on top of the head between the eyes. The left caudal lobe is slightly longer than the right lobe. The parapodia only cover the sides of the body.
The body is creamish white with contrasting, strong black markings that are arranged in circles. Though distinctive, the colour patterns are variable. The extent of the black markings on the body vary between individuals - these can either be thin as to appear reticulated (most often), or very thick as to give the appearance of an all black animal. Specimens of the black colour form of Philinopsis pilsbryi have a superficial resemblance to P. gardineri, but that always has blue markings on the parapodial margins.
The diet is presumed to be polychaete worms. The spawn is unknown.
There are to date (mid-September, 2011) five species of Philinopsis reported from Okinawan waters. The five are:
Philinopsis falciphallus P. gardineri P. pilsbryi The above featured animal P. reticulata P. speciosa