Body (excluding appendages)
Up to 11mm long. Translucent white, with freckles of white surface pigment scattered over entire dorsal surface and concentrating into patches anteriorally [1]. Red, orange or brown pigment forms a streak from rhinophore to oral tentacle in front of it, a curved streak behind each rhinophore and a medial patch between anterior cerata; total of 5 marks [7].
Cerata
Conceal sides and most of dorsum of body behind the pericardium. Arranged in rows on each side of the body. Translucent white revealing olive-green [5], dark brown [7] or brown [1] internal digestive gland which stops short of the apex. Freckles of reflective yellow-white or golden pigment are scattered over most of the surface, but stop with the digestive gland short of the apical cnidosac area which is translucent white with a thin band of freckles just below the apex [6].
Rhinophores
Smooth. Translucent white, densely covered in freckles of white pigment except for an encircling band of dull translucent orange-brown about a third of the way up [2].
Head
Translucent white oral tentacles with freckles of white pigment mainly in distal half [7] and, sometimes, a very faint band of translucent orange about a third of the way along.
Foot
Slight rounded swelling at anterior, no propodial tentacles [3]. Translucent white sole, white blobs of ovotestis may be visible.
- In addition to five red, orange, or brown marks on C. foliata, a sixth transverse one at front of head connecting oral tentacles.
- Much yellow on rhinophores and oral tentacles, and a yellow longitudinal streak on body between rhinophores.
Low water spring tides on rocky shores, and shallow sublittoral. On or near its hydroid prey, including Abietinaria abietina (EML), Sertularella polyzonias (EML), S. gayi (EML), Tubularia spp. (EML), Obelia geniculata (EML), Halecium spp. (EML) and Dynamena pumila (EML). Simultaneous hermaphrodite. Broad ‘C’ shape spawn masses [4] May to August.
Norway and Faeroes to Brittany. Records from the Mediterranean may refer to Cuthona genovae (GBIF map). Scattered records round Britain and Ireland. (UK interactive distribution map.NBN.)
Alder, J. & Hancock, A. 1845-1855. A monograph of the British nudibranchiate mollusca. London, Ray Society.
Thompson, T.E. & Brown, G.H. 1984. Biology of opisthobranch molluscs 2. London, Ray Society.
Current taxonomy: World Register of Marine Species (WoRMS).
Irish distribution and prey organisms:
Picton, B.E. & Morrow, C.C., 2010. Encyclopedia of Marine Life of Britain and Ireland (EML).