Picton & Brown, 1978
Previously known only from the British Isles, but see message below with records from Holland and Norway
Manse Reef, Loch Leven, west coast of Scotland. 15mm long. 9 June 2002. Photo: Jim Anderson.
Although only easy to see in adults, one of the most characteristic features of this species is that the bases of the cerata are suffused with red. Streaks of white cover the dorsal surface of the cerata and towards the tip the white becomes more concentrated. The upper half of the rhinophores are mostly white and there is a darke reddish band about midway. One other distinguishing feature is that the dorsal surface of the oral tentacles have a continuous band of white . Adults grow to about 18mm in length. It feeds on the common hydroid Halecium halecinum. A very similar looking species, Cuthona amoena, feeds on the same hydroid. It differs in having a brown band in the middle of the oral tentacles.
Rudman, W.B., 2002 (June 18) Cuthona rubescens Picton & Brown, 1978. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/cuthrube