Hypselodoris cf. bertschi from Kerama Is

December 17, 1999
From: Atsushi Ono

Dear Bill,
I found this small Hypselodoris species in Kerama Is. [near Okinawa].
This is very similar to H. carnea, but I have never seen one over 10mm long in my area.

I have seen over 10 individuals at a shallow coral reef and biggest was about 8mm. This is considered to be common species at Kerama Is. in autumn season.

In my pictures the upper is 7.5mm long, and the lower is 5.5mm long.

At first I thought this is a H. maculosa variation or juvenile. But I do not think so now. Could you help me to identify it?

Atsushi Ono


Ono, A., 1999 (Dec 17) Hypselodoris cf. bertschi from Kerama Is. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1686

Dear Atsushi,
I think this is a particularly interesting find. I may be wrong but I think this is a species which Terry Gosliner & Rebecca Johnson have recently described as Hypselodoris bertschi, a species only known from the Hawaiian Islands.

The only colour differences I can find in their description is that they say there is an orange band around the mantle margin and the white gills have an orange rachis. However Kay & Young's description (1967) of the Hawaiian species [as Hypselodoris lineata (Pease)] states that the 'margin is sometimes edged with white, sometimes with a narrow band of blue, and at other times margined with orange-yellow' and that the gills are 'transparent white with splashes of orange at the tips.'

A photo in Bertsch & Johnson's Hawaiian Nudibranchs (1981; p.65) is almost identical to your animals. If they are the same this is the first record outside of Hawaii. Hawaiian animals grow to about 35mm long. Mike Miller has recently posted a picture from Hawaii on his Slug Site Nudi of the week 171.

Have you seen any colour variation in Kerama Island animals? It would be interesting to know if they ever have an orange margin to the mantle.

Best wishes,
Bill Rudman.

Gosliner, T.M. & Johnson, R.F. (1999) Phylogeny of Hypselodoris (Nudibranchia: Chromodorididae) with a review of the monophyletic clade of Indo-Pacific species, including descriptions of twelve new species. Zoological Journal of the Linnean Society, 125: 1-114.

Kay, E.A. & Young, D.K. (1969) The Doridacea (Opisthobranchia: Mollusca) of the Hawaiian Islands. Pacific Science, 23(2): 172-231.

Rudman, W.B., 1999 (Dec 17). Comment on Hypselodoris cf. bertschi from Kerama Is by Atsushi Ono. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1686

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