Roboastra gracilis is rare in the Marshalls, known from several specimens at Enewetak and Kwajalein Atolls and three more from Rongelap reported by John and Lynette Flynn. All were found under lagoon reefs and pinnacles under dead coral or crawling on sand at depths of 1 to 15 meters. A 17mm specimen at Enewetak deposited an egg mass containing yellow ova, 75µm in diameter within capsules of about 95µm. Specimens we have seen in the Solomons, if they are really the same, seem to have much taller gills.
This brightly colored specimen was found on a Kwajalein lagoon reef at a depth of about 8m on 9 August 2009.
We also have an animal from Hawaii we are calling R. gracilis, but it lacks most of the dark pigment of the Marshall Islands specimens.
Created 3 January 2007
Updated 3 May 2021