Dendronotus frondosus (Ascanius, 1774)

18 October, 2015.
SS Tabarka, Scapa Flow in the Orkney Islands.
30 mm animal at 14 metres. Water temperature 11°C.
Sony α6000  in Nauticam housing, Zeiss 50 mm macro lens and 2 x Inon D-2000 flashes.

for more information about this species go to one of the links below
OPK - Opistobranquis nudibranchs of the british isles sea slug forum