East Pacific - Monterey Bay, California to Ensenada, Baja California, Mexico (Behrens & Hermosillo, 2005).
Locality: Buchanan's Reef, Palos Verdes, 20 metres, California, USA, Pacific Ocean, 22 July 2007, Rocky reef. Length: 20 mm. Photographer: Jim Lyle.
Body and mantle is a translucent brownish with scattered brown blotches. It has a broad mantle skirt and a high median ridge with a higher central tubercle which is whiter than the rest of the mantle. The gills are protected by three upright lobes along the naterior edge of the gill pocket. It grows to about 60 mm in length.
Behrens, D. W. and Hermosillo, A. (2005) Eastern Pacific Nudibranchs. A Guide to the Opisthobranchs from Alaska to Central America. Monterey, California, Sea Challengers. 1-137.
Bertsch, H. and Gosliner, T. M. (1986) Anatomy, distribution, synonymy, and systematic relationships of Atagema alba (O'Donoghue, 1927) (Nudibranchia: Doridacea). The Veliger, 29: 123-128.
Rudman, W.B., 2007 (July 26) Atagema alba (O'Donoghue, 1927). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/atagalba