Key to Flabellina in the North Atlantic

by Bernard Picton & Jussi Evertsen

This is an amalgamation of keys prepared by Bernard Picton and Jussi Evertsen. It does not include Flabellina parva and Flabellina islandica. See Flabellina - Nth Atlantic page for background information.

1. Cerata clustered, with clear gaps between first three clusters 2
Cerata unclustered, arising all along the notal rim 7
2. Anus located in the interhepatic space (between first and second anterior group); cerata on a common expansion of the notum (peduncle) 3
Anus located posterior to the interhepatic space (below the second anterior group); cerata arising from a notal ridge 4
3. Body colour purple, cerata with white rings, rhinophores equally as long as the oral tentacles pedata
Body white, cerata capped with white, rhinophores twice as long as the oral tentacles pellucida
4. White lines on head tentacles, centre of back and sides of body lineata
Tentacles and tail with white splashes but no continuous lines 5
5. Rhinophores smooth; mature individuals at 15 mm; narrow white rings on cerata; anus located below first row of cerata in the second groupgracilis
Rhinophores wrinkled; mature individuals greater than 15 mm;
anus located posterior to the first row of cerata in the second group
6. Rhinophores with a pink hue; broken white line along midline of back which extends as a thin white line on median ridge, interspersed with warts, on elongate tail; thin lines on dorsal surface of rhinophores and fine or broken lines around tips of cerata; anus located below the third row in the second group verrucosa
Rhinophores translucent white; white splashes at tip of tail and head tentacles; anus located below the second row of cerata in the second group browni
7. Body and head expanded to the sides; anus located in the posterior 2/3 of the body salmonacea
Body slender, and head not expanded to the sides; anus is located in
the anterior half of the body
8. Rhinophores rough and wrinkled but without miniscule papillae; cerata very numerous and crowded and extending on to tailborealis
Rhinophores wrinkled and densely set with miniscule papillae; cerata evenly distributed and spaced apart, not extending onto tail nobilis

Authorship details
Picton, B.E. & Evertsen, J., 2001 (July 27) Key to Flabellina in the North Atlantic. [In] Sea Slug Forum. Australian Museum, Sydney. Available from