Like Costasiella vegae, this unidentified species of Costasiella seems relatively common in the Marshalls, where it is found almost exclusively on clumps of what appears to be the algae Avrainvillea amadelpha. Both species of Costasiella may inhabit the same clump of algae. The algae grows in fairly large solitary clumps on the sandy lagoon slope at depths of 6 to 15m. The animals shown on this page appear to be the species called Costasiella sp. 1 on the Sea Slug Forum. It seems likely that these and what we have as Costasiella kuroshimae are just variants of one species.
This specimen was found on Avrainvillea on a Kwajalein Atoll lagoon reef at 8m on 26 July 2009.
The one below was on Avrainvillea on a Kwajalein Atoll lagoon sand flat at a depth of 8m on 1 June 2010.
The next specimen was from the same area on 3 October 2011.
Created 17 August 2008
Updated 5 March 2016
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