Description: The body is translucent white with a pinkish hue over the head and tentacles. The red oesophagus is visible through the epidermis. Often there is a small patch of white pigment between the rhinophores. White speckling is present on the head, tentacles and cerata. The tips of the cerata are covered with yellow/white pigment. The oral tentacles are very long and mobile and the rhinophores are smooth. Adult specimens usually range in length between 17-38mm.

Habitat: Thought to feed on Tubularia larynx and possibly other hydroids.

Distribution: The only British records are from Lough Hyne, SW Ireland, elsewhere it has been reported from Arcachon in the Bay of Biscay and the Mediterranean Sea. A record of this southern species from Denmark must be considered doubtful.

Similar Species: Facelina bostoniensis is similar, but the annulate rhinophores of F. bostoniensis distinguish it from F. dubia.

Key Identification Features:

• Propodial tentacles, long oral tentacles and smooth rhinophores present.
• Cerata with patches of dark surface pigment.

Distribution Map from NBN: Facelina dubia at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Facelina dubia at iNaturalist World Species Observations database.

WoRMS: Facelina dubia at World Register of Marine Species. Accepted name: Facelina dubia Pruvot-Fol, 1948. AphiaID: 139910.

Classification: Biota; Animalia; Mollusca; Gastropoda; Heterobranchia; Euthyneura; Ringipleura; Nudipleura; Nudibranchia; Cladobranchia; Aeolidioidea; Facelinidae; Facelina