Gymnodoris sp. e139

This unidentified Gymnodoris is known from several specimens from Enewetak and Kwajalein Atolls. The Enewetak specimen shown in the first three photos below was crawling on rubbly sand at night at a depth of 12 meters on a lagoon pinnacle reef. This species resembles Gymnodoris sp. e005 in the presence of a dorsal keel near the posterior end, and they could just be larger specimens of that species. All specimens of G. sp. 005 were on fine sand in deeper water. The radular teeth of the two species are similar, but the proportions differ: the innermost lateral of G. sp. e139 was nearly twice as large as the largest of the other teeth in mid-halfrow, while in G. sp. e005, the same tooth was only about one and a half times as large. The radular formulae differed as well: for G. sp. e139, the formula was 21x21.0.21 and three radulae examined for G. sp. e005 were 21x36.0.36, 22x40.0.40, and 20x30.0.30.

The next few shots show the second specimen, found crawling on sand on 20 October 2008 on a Kwajalein Atoll lagoon reef at a depth of about 7m. This one measured 17mm in length. It resembles the species called Gymnodoris sp. 11 in Gosliner et al (2008).

When crawling, the animal would stop every few seconds and stick its head under the top layer of sand, but it would not try to bury itself. We suspect it was hunting for food, possibly some kind of opisthobranch mollusk that lives among the sand grains.

Another 7mm specimen was sighted at Kwajalein on 9March 2013 at night on a lagoon sandy reef.

Created 1 January 2007
Updated 27 May 2013

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