Known only from Denmark?
Original figures from Lemche (1935). Fig. 6.: Eastern part of Nyborg fjord, Funen, Denmark. Very shallow water (0,2-0,3 m. depth), in Cladophoraceae. Oct. 19, 1929.
Total length of the living animal 7-8 mm. The colour of these animals is greenish-black, head and foot lighter greyish. The rhinophores, the tail, and the elevated part of the back are whitish, the back, however, showing a number of pigmented spots. The lightest parts are sprinkled with small opaque white dots, and some white dots are also scattered over the back. The cerata are of a greenish-black, although not quite so dark as the body and interspersed with lighter spots. Through the skin two liver-branches are faintly seen running backward under the narrow space between the light field on the back and the innermost cerata. The branches give off smaller branches to the cerata.
The radula consists of a single row of spoon-shaped teeth of which four are situated in the ascending and five in the descending part of the row.
See message below for full original description. See also Kathe Jensen's message comparing this species with Ercolania funerea. Originally named Stiliger niger, the species name changes to nigra because of grammatical rules, Ercolania being feminine and Stiliger masculine.
Lemche, H. M. (1935). On some nudibranchiate gastropods from the northern Atlantic. Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening, 99: 131-148. [Note: although whole volume was not published until 1936 - reprints were distributed in 1935].
Rudman, W.B., 2002 (November 7) Ercolania nigra (Lemche, 1935). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/erconigr
Re: Calliopaea bellula - Ercolania cf. viridis & eggs
From: Kathe R. Jensen, April 1, 2009
Information on Ercolania nigra
From: Bill Rudman, November 9, 2002