Sclerodoris cf tuberculata Eliot, 1904

We recorded eight specimens of this species, which was originally recorded from Hawaii as Halgerda rubra by Kay & Young (1969). Although our specimens are externally identical to those of Sclerodoris tuberculata that we have seen in the Marshalls, Kay & Young noted that the ejaculatory duct possesses cirral hooks that have not been reported in S. tuberculata. There are a couple of possibilities here. Maybe our Marshall Islands specimens are the same as the Hawaiian ones; we have not dissected out the reproductive system to check for hooks. It is also possible that the hooks vanish in preservative. We found that a number of species of Chromodoris possess penial armature that can be seen in fresh but not in preserved specimens. Since I dislike breathing formalin, the specimens we collected at Enewetak for dissection were kept frozen in seawater until dissected. Many Chromodoris species dissected this way revealed spines in the ejaculatory duct. If they had been preserved for a few days in formalin or alcohol prior to dissection, the spines were missing. Possibly something like a defensive chemical is leeching from the nudibranch's body in preservative and dissolving the spines. Anyway, it is possible that something similar is happening here. Maybe dissections of frozen but unpreserved specimens of S. tuberculata will reveal the hooks seen by Kay & Young. In the meantime, we will keep the identification as questionable. We recorded eight specimens: six of them from night dives at Pupukea and Makua, Oahu; one exposed on the wall in the Magic Island channel; and one under a rock at a depth of about three quarters of a meter on the reef off Hauula, Oahu. The Hauula specimen was by far the largest, measuring more than 100mm in length.

The specimen immediately below is the large one found at Hauula.

Links:
Sea Slugs of Hawaii
Sea Slug Forum (Sclerodoris tuberculata)
Marshall Islands Sea Slugs

Created 20 April 2009

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