Differences between species of Ancula

March 26, 2000
From: Sylvain LE BRIS


I would like to know if Ancula pacifica from Alaska to California and Ancula gibbosa from the British Isles are the same species ?

Sylvain LE BRIS


LE BRIS, S., 2000 (Mar 26) Differences between species of Ancula. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1958

Dear Sylvain,
I am not sure if they are or not. Thompson thought they were but I can't find any other authors who say the same. The European animal has both white and an orange lined colour forms and the orange one seems identical in colour to the A. pacifica. Perhaps someone from the American west coast can give us their opinion.

Ancula pacifica, Macfarland, 1905 from the west coast of North America is white with three yellow lines running along the body and the rhinophores, gills and extra appendages have an apical yellow band. I think there are records from Japan as well.

A. gibbosa (Risso, 1818) is reported from the western Mediterranean around the northern Atlantic coast to the White Sea, Greenland & Iceland and across the New England coast of N. America. Thompson (1976) describes it as white with yellow capped rhinophores, gills and extra appendages, but does not mention yellow/ornage longitudinal lines. He synonymises Ancula pacifica with this species.

Photos of both species are available on websites. See Erwin Koehler's list at : http://www.medslugs.de/Opi/Opisthobranchia.htm

Best wishes,
Bill Rudman.

Rudman, W.B., 2000 (Mar 26). Comment on Differences between species of Ancula by Sylvain LE BRIS . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1958


Ancula gibbosa

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