Chromodoris geometrica from Marshall Ids

August 21, 1999
From: Scott Johnson

Hi Bill,

Attached are several photos of variation in Chromodoris geometrica in the Marshall Islands. The species is not uncommon at Kwajalein and Enewetak Atolls. Smaller specimens often, but not always, have yellow-orange rhinophores and gills, while in the larger adults (photo E053-6), the rhinophores and gills are nearly always green. Background dorsal color also varies from gray to black, and larger specimens often have scattered white spots in the black areas.

E053-1 shows a very small individual from Enewetak on the typical prey sponge, tentatively identified as Aplysilla violacea. Although a bit difficult to see in this picture, the specimen of C. geometrica in E053-1 is also interesting because its gills protrude from underneath the posterior mantle margin -- obviously a deformity.


Johnson, S., 1999 (Aug 21) Chromodoris geometrica from Marshall Ids. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Scott,
Thanks for the sponge photos and the colour variation. Chromodoris ambiguus, Chromodoris thompsoni and the spotted form of Chromodoris fidelis all feed on similar looking purple sponges.

The animal with the gills beneath the mantle is interesting. Charles Eliot described a specimen of Hypselodoris infucata as a new species and genus, Chromodoridella mirabilis Eliot 1905, because it had the gills attached below the mantle edge.

Best wishes,
Bill Rudman.

Reference: Eliot, C.N.E. (1905). On some nudibranchs from the Pacific, including a new genus, Chromodridella. Proceedings of the Malacological Society of London, 6: 229-238

Rudman, W.B., 1999 (Aug 21). Comment on Chromodoris geometrica from Marshall Ids by Scott Johnson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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