Specimen from 3 m depth in Etang de Thau, Mediterranean France. © J.L. Peralta.
Features below are based on / calculated from Bergh (1882) of a single 40 mm, live specimen of F. vicina (lost holotype).
Cerata up to 22.5 % of body length. [ Etang de Thau specimen to c. 40%, Croatia to 50%.]
Proximal half of oral tentacles and anterior face of cerata have bluish-silver iridescence. [Strongly developed iridescence on Etang de Thau specimen.]
Cerata have a chalky-white tip. [Like Croatian finds, the Etang de Thau specimen also has an opaque white line running down from the white tip.]
Long oral tentacles nearly twice as long as rhinophores, 25% of body length. [Etang de Thau specimen over twice as long as rhinophores, c. 47% of body length, Croatia to 51%]
There are several other images of F. vicina from Etang de Thau and NW Mediterranean on Flickr and iNaturalist www.inaturalist.org/observations?place_id=any&taxon_i…