Fionidae

Fionidae
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Order:	Nudibranchia
Suborder:	Aeolidacea
Superfamily:	Fionoidea
Family:	Fionidae; Gray, 1857
Genera
	See text

Fionidae is a family of sea slugs, aeolid nudibranchs, marine gastropod molluscs in the superfamily Fionoidea.

General characteristics

The animal bears four simple tentacles and numerous papillose branchiae. The vent is situated latero-dorsally. The mouth is equipped with jaws, and the lingual membrane bears a single series of plates.

Taxonomic history

This family was expanded to include Tergipedidae, Eubranchidae and Calmidae as a result of a molecular phylogenetics study. This was reversed in 2017 with further DNA evidence and a re-interpretation of genus and family characteristics.

Genera

According to Korshunova et al. (2025), genera within the family Fionidae include:

Fiona Alder & Hancock [in Forbes & Hanley], 1853
Tergiposacca Cella, Carmona, Ekimova, Chichvarkhin, Schepetov & Gosliner, 2016

Other genera not mentioned in Korshunova et al. (2025) include:

Zatteria Eliot, 1902

References

1 2 MolluscaBase eds. (2026). MolluscaBase. Fionidae J. E. Gray, 1857. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=23039 on 2026-03-30
↑ Gray, J.E. (1857). Guide to the systematic distribution of Mollusca in the British Museum. Part I. [Gastropoda]. London: British Miseum. p. 227. Retrieved 8 August 2026. This article incorporates text from this source, which is in the public domain.
↑ Cella, K; Carmona Barnosi, L.; Ekimova, I; Chichvarkhin, A; Schepetov, D; Gosliner, T. M. (2016). A radical solution: The phylogeny of the nudibranch family Fionidae. PLoS ONE. 11(12): e0167800.
↑ Korshunova, T.; Martynov, A.; Picton, B. (2017). Ontogeny as an important part of integrative taxonomy in tergipedid aeolidaceans (Gastropoda: Nudibranchia) with a description of a new genus and species from the Barents Sea. Zootaxa. 4324(1): 1.
↑ Korshunova T.; Fletcher K.; Martynov A. (2025). The endless forms are the most differentiated—how taxonomic pseudo-optimization masked natural diversity and evolution: the nudibranch case Zoological Journal of the Linnean Society, Volume 204, Issue 4, August 2025, zlaf057,

External links

Media related to Fionidae at Wikimedia Commons

[WoRMS-1] 1 2 MolluscaBase eds. (2026). MolluscaBase. Fionidae J. E. Gray, 1857. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=23039 on 2026-03-30

[2] Gray, J.E. (1857). Guide to the systematic distribution of Mollusca in the British Museum. Part I. [Gastropoda]. London: British Miseum. p. 227. Retrieved 8 August 2026. This article incorporates text from this source, which is in the public domain.

[3] Cella, K; Carmona Barnosi, L.; Ekimova, I; Chichvarkhin, A; Schepetov, D; Gosliner, T. M. (2016). A radical solution: The phylogeny of the nudibranch family Fionidae. PLoS ONE. 11(12): e0167800.

[4] Korshunova, T.; Martynov, A.; Picton, B. (2017). Ontogeny as an important part of integrative taxonomy in tergipedid aeolidaceans (Gastropoda: Nudibranchia) with a description of a new genus and species from the Barents Sea. Zootaxa. 4324(1): 1.

[Korshunova-5] Korshunova T.; Fletcher K.; Martynov A. (2025). The endless forms are the most differentiated—how taxonomic pseudo-optimization masked natural diversity and evolution: the nudibranch case Zoological Journal of the Linnean Society, Volume 204, Issue 4, August 2025, zlaf057,