Costasiella sp. 1. from Guam

March 23, 1999
From: C Carlson & P.J. Hoff


We don't have a name on this one but thought we might show a slightly whiter color form. There are two animals in the scan so the length may be misleading. This is an interesting Costasiella since it seems to be found almost everywhere except on Avrainvilla -- the common host for most Costasiella. We quite often find it in areas where there are haminoeid egg masses though haven't observed them feeding. Aside from Guam, we have this species from Pagan & Saipan in the Northern Marianas as well as Yap and Palau

UPPER PHOTO: 2 animals, about 3.5mm; Guam, Cocos Lagoon, 1m, October 1971
LOWER PHOTO: ventral view showing foot; 3.0mm; Guam, Toguon Bay, 8m; 23 March 1989.

Clay Carlson & Patty Jo Hoff

Carlson, C. & Hoff, P.J., 1999 (Mar 23) Costasiella sp. 1. from Guam. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Clay & Patty Jo,
Thanks for the photos. I am curious about the dark green in the ventral photo. Is the white pigmentation a skin colour on the dorsal surface or does this species change from green to white depending on diet?
Bill Rudman.

Rudman, W.B., 1999 (Mar 23). Comment on Costasiella sp. 1. from Guam by C Carlson & P.J. Hoff. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Costasiella sp. 1.

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