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 group | gracilis | |
| Rhinophores wrinkled; mature individuals greater than 15 mm; anus located posterior to the first row of cerata in the second group | 6 | |
| 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 | |
| 8. Rhinophores rough and wrinkled but without miniscule papillae; cerata very numerous and crowded and extending on to tail | borealis | |
| Rhinophores wrinkled and densely set with miniscule papillae; cerata evenly distributed and spaced apart, not extending onto tail | nobilis | |
Picton, B.E. & Evertsen, J., 2001 (July 27) Key to Flabellina in the North Atlantic. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/flabkey1
