Opisthobranch of the Week Data
Cerberilla asamusiensis is considered by Atsushi Ono to be rare in waters off the Keramas* as he reports having seen only the above featured animal in the waters of Zamami Island. The above animal was found on a sandy bottom (pers. comm.) and is used here with Atsushi's kind permission. As of the current date I've not personally seen specimens in the waters of Okinawa's main island.
Cerberilla asamusiensis is similar in color to C. annulata and Bill Rudman (2002) points out that ". . . in that species the yellow and black bands on the cerata are bands of regular width and outlined in white. In C. asamusiensis the yellow-orange region covers a broad section of the upper ceras and the black region is cap-shaped. It also differs in the blackish rhinophores and the black line that runs across the front of the head and along the front edge of the oral tentacles to join the black upper half of the oral tentacles."
Baba (1940) originally described Cerberilla asamusiensis from material collected from Mutsu Bay, Japan. In a more recent publication, Baba (1976) describes the species as follows (I've included only his description of external morphology):
The main features of the body colors in the type of Cerberilla asamusiensis were re-established by Mr. Akiba on his specimen collected from Sagami Bay. According to him, there occurs a black line running transversely along the anterior border of the head to the bases of the oral tentacles. An additional black line is present at each side of the rhinophores which are black to the tip when seen from the rear. Each branchial papilla has a black spot down the apex on the outer (= upper) surface. Often this spot is accompanied with a yellow marking situated below it. The head above, and the anterior margin of the foot are tinted yellow. The bare space of the back is slightly dark. The general integument of the rest of the body is colorless. The living animal measured about 22mm in length.
The branchial papillae are arranged in simple oblique rows on either side. They number up to 16 in the largest rows. The genital orifices lie immediately below the 3rd right row. The anus opens below the 6th right row, and thus it is seemingly pleuroproctic in position.
In addition to the above featured C. asamusiensis, the following Cerberilla species have been previously featured on these pages:
* Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.