Information on Halgerda maricola

October 16, 2001
From: Shireen Fahey

Dear Bill,
Here is some information on, Halgerda maricola, one of the new species of Halgerda that Terry Gosliner and I have just published.

PHOTO: (WAMS 12318). Specimen, 17 mm, from Rottnest Island, Western Australia. 23 m depth, December, 1998. Photo by G. Gunness. (Fahey & Gosliner, 2001: Fig. 3C).

Halgerda species aren't the most common nudibranch genus on the reefs, but Halgerda maricola is even harder to find. It's a very small species and it likes to hide among the rich substrate off Rottnest Island in Western Australia. This species was named for a very avid diver and photographer, Mary Gudgeon, the namesake of Mary's Reef on the northeast side of Rottnest. Halgerda maricola has a white background color with low ridges that have thin orange crests. There are small black dots in the concavities of the ridges and the mantle margin and foot are both lined in yellow. The rhinophores and gill are both white, with small dark splotches of color at the tips. This species is most similar to Halgerda formosa. The differences between these two species include the following: H. maricola has dark pigmentation on the rhinophore tips but H. formosa has dark coloration on the stalks too. H. maricola has dark spots on the dorsum that are confined to the ridge depressions, but H. formosa has randomly scattered dark spots. The tips of the gills of H. maricola are dark, but H. formosa has white gill tips. The reproductive differences also separate these two species.

Reference:
• Fahey, S.J. & Gosliner, T.M. (2001) On the genus Halgerda (Nudibranchia: Halgerdidae) from Western Australia with descriptions of four new species. Bollettino Malacologico, 37(5-8): 55-76.

Best wishes,
Shireen

sfahey@mailbox.uq.edu.au

Fahey, S., 2001 (Oct 16) Information on Halgerda maricola. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5476

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