Hypselodoris sp. 8
Intertidal Flats, Changi, Singapore. Photo: Ria Tan.
On first sight this looks like Hypselodoris kanga, but even allowing for the colour variation we find in that species, this is quite different. The most obvious difference is the shape and the colour of the gills. In H. kanga the gills are triangular in cross-section, and so there is an outer smooth side to them on which there are yellow spots. In this animal the gills are what we call 'simple', they are in one plane, so the outer side is just a thin edge. Another difference is that the gills have secondary branching which is quite unusual in the family.
There are a number of species with quite similar colour patterns, the most common being Hypselodoris infucata. When I revised that group some years ago (Rudman, 1977) I noted that an animal from Singapore which had been identified as Glossodoris semperi Bergh by Lim & Chou (1960) was almost certainly an unnamed species. It has never been reported since, but I am sure it is the same as the one in your photo.
• Lim, C. F., & L. M. Chou. (1970) The doridid Glossodoris semperi (Bergh) recorded from Singapore waters. Malayan Nature Journal, 23(2-3): 118-120.
• Rudman, W.B. (1977) Chromodorid opisthobranch Mollusca from East Africa and the tropical West Pacific. Zoological Journal of the Linnean Society, 61: 351-397.
Rudman, W.B., 2003 (January 29) Hypselodoris sp. 8 [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/hypssp8