Southwestern Western Australia, east coast South Africa. (See message below).
Transits Reef, Rottnest Is, Western Australia, March 1982, approx 40mm long alive. PHOTO: G. Saueracker.
The mantle is translucent white with many large opaque blotches all over, except around the edge which has a broad band of opaque white with a thin yellow band right at the edge. The rhinophore stalk is transparent and the club is opaque white with a yellow dash along the upper part of the anterior and posterior midline of the club. The simple gills are translucent white with red lining the inner and outer edge of each gill. The underside of the animal is white, somewhat more opaque around the edge of the foot which is bordered with a yellow line.
The animal is relatively high, the mantle clongately oval with the broad overlap thrown into a series of folds down each side, with a particularly prominent fold on each side halfway down the body. The gills are simple, and arranged in an arc open posteriorly, each end spiralling up into an internal secondary arc on each side. No information is available on whether the gills are waved rhythmically.
Glossodoris undaurum is one of a group of chromodorids which are white with a yellow border which I have previously grouped together for identification purposes as the Chromodoris aureomarginata colour-group. Only a few of those species belong to the genus Glossodoris. Glossodoris pallida has distinctive white markings on the mantle and the mantle border of Glossodoris electra is a wide golden yellow band and the gills and rhinophore clubs are a brownish colour. Glossodoris undaurum is distinguished by the red-lined gills, yellow tipped rhinophores, and the opaque white patches which are usually visible all over the mantle.
•Rudman, W.B. (1985) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Chromodoris aureomarginata, C. verrieri and C. fidelis colour groups. Zoological Journal of the Linnean Society 83: 241-299.
•Rudman, W.B. (1986a) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: The genus Glossodoris Ehrenberg (= Casella, H. & A. Adams). Zoological Journal of the Linnean Society 86(2): 101-184.
•Rudman, W.B. (1990b) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: further species of Glossodoris, Thorunna and the Chromodoris aureomarginata colour group. Zoological Journal of the Linnean Society, 100(3): 263-326.
Rudman, W.B., 1999 (November 8) Glossodoris undaurum Rudman, 1985. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/glosunda