Halgerda sp from Zanzibar
November 11, 2005
From: Wilhelm van Zyl
Dear Bill,
I recently returned from a diving trip to Zanzibar. Zanzibar and especially Pemba island is a Nudibranch enthusiast's dream. On one particular dive I photographed 9 different species.
I am sending you 2 pictures of what I believe is Halgerda formosa. The first specimen block spots only on the mantle's edge. The second one has spots in almost every segment formed by the ridges.
Locality: Pemba Island, Zanzibar, Tanzania. Indian Ocean. Depth: 14 m. Length: 2 cm. 14 October 2005. patchy coral and sandy reef. Photographer: Wilhelm van Zyl
Regards
Wilhelm van Zyl
diving@cyberdale.co.za
Van Zyl, F.W., 2005 (Nov 11) Halgerda sp from Zanzibar. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15243Dear Wilhelm,
I am jealous of you being to Zanzibar. I lived there for some months in 1971 and returned a few times while living later in Dar es Salaam. I will always remember its beauty, the abundant nudibranchs, and the friendliness of the people.
Your animals are very similar to one I had from Zanzibar (Rudman, 1978) and misidentified as Halgerda punctata. I have discussed its identity, and the identity of H. formosa in an earlier message [#11828]. Basically I think your animals are a pale colour form of Halgerda wasinensis. See message #11477 for some photos of intermediate colour forms.
Your photos are very useful as they help us to build up a picture of its distinctive colour characters. Three things which seem to be consistently present are that only the upper two-thirds of the rhinophore clubs are black, the tips of the rhinophores are white, and the gills are essentially white with black pigmentation restricted to the upper half of each gill.
Best wishes,
Bill Rudman
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