Aldisa williamsi
Photo Curtesy of Angel Valdes

Aldisa williamsi Elwood, Valdes and Gosliner 2000

Blue is not a color I easily associate with opisthobranchs, but in the case of this recently described species, it surely is. This species has a bluish-grey body covered with white tipped tubercles. There is a distinct black band forming an oval on the dorsum and a black line between the rhinophores. Aldisa williamsi bears strong resemblance to the porostome dorid, Phyllidiella pustulosa (Cuvier, 1804), and as the authors point out, probably mimics it. The acid secreting P. pustulosa lacks a dorsally situated gill and has no radula, of course.

Aldisa williamsi is known from Papua New Guinea and photos from Doris #10 Sulawesi, Indonesia.

Batangas, Philippines 1997

Aldisa williamsi is named for Dr. Gary Williams , Associate Curator at the Dept. of Invertebrate Zoology and Geology at the California Academy of Sciences. Gary is also a coauthor of our book Coral Reef Animals of the Indo-Pacific.. Gary is picutred second to left prior to taking in a night dive at Batangas, Philippines with fellow branchers; Clay Carlson, Gary , Dave Behrens, Michael Miller and Terry Gosliner.

Another somewhat similar species is Discodoris liturata Bergh, 1905. Other look-a-likes include Bill Rudman s Doris sp. 2 , which as been recently described as Aldisa erwinkoehleri Perrone 2001, after friend and Brancher, Erwin Koehler . It is also similar to the Chromodoris sp., at the bottom of page 213 in Debelius .

The reader is invited you visit Erwin's Medslugs site to sample the many terrific species profiles he offers. Of even more value is Erwin's List of the Opisthobranchs of the World where you can go to find virtually every photograph of sea slugs on the internet today.

Dave Behrens
Danville, Calif
Feb. 2002


Elwood, Hillary R., Angel Valdes & Terrence M. Gosliner. 2000. Two new species of Aldisa Bergh, 1878 (Mollusca, Nudibranchia) from the tropical Indo-Pacific. Proc. Calif. Acad. Sci. 52(14): 171-181.

Perrone, A. 2001. A new species of Nudibranchia of the genus Aldisa Bergh (Gastropoda, Opisthobranchia) Basteria 65: 105-116

Taxonomic information courtesy of:

David W. Behrens

Author: Pacific Coast Nudibranchs
Co-Author Coral Reef Animals of the Indo Pacific
Propriator of Sea Challengers Natural History Books !

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