Sagaminopteron nigropunctatum

Sagaminopteron nigropunctatum Carlson & Hoff, 1973

Sagaminopteron nigropunctatum was originally described from Guam, Mariana Islands. The species has since been found in many other areas of the Western Pacific as well as the Indian Ocean. Adult animals average about 9mm in length though specimens up to 16mm have been found. S. nigropunctatum is commonly associated with a gray sponge,Dysidea granulosa and on occasion can be found on Dysidea herbacea. The animals are difficult to see on their sponge host since their color and texture match that of the sponge.

The above photo is a 8mm Sagaminopteron nigropunctatum with egg masses from Palau. It was collected 24 Sept '96 at a depth of 13m; 'Wonder Channel', Palau. The host sponge in this case is Dysidea herbacea.

Sagaminopteron is a genus in the family Gastropteridae in the Opisthobranch subclass Cephalaspidea. Further information on the Gastropteridae can be found in a paper by Dr. Terry Gosliner (1989) in The "Veliger. "

Clay Carlson,
Merizo, Guam

The Gastropteridae consists of four genera, Gastropteron, Enotepteron, Siphopteron and Sagaminopteron. The vast majority of the almost thirty species in the family are found in the Indo-Pacific tropics. Most species are small, less than an inch in length. They are unusual for cephalaspideans in that the shell is reduced to a flat, internal plate, found under the skin in the hind end of the animal, or is entirely absent in adults. Most species are able to swim by flapping their parapodia and "flying" through the water.

Species of Sagaminopteron (The genus is named for Sagami Bay, Japan, where Emperor Hirohito collected so many opisthobranchs that have been studied by Kikutaro Baba) are all found on sponges, upon which they feed. The feeding biology of other members of the family is virtually unknown.

Dr. Terry Gosliner
San Francisco, CA

Photos courtesy of Clay Carlson

Clay Carlson/Terry Gosliner
Makeshift Laboratory
Batangas, Philippines
April, 1997

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