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Facelinidae

Facelinidae Bergh, 1889

This is a family of aeolid nudibranchs belonging to the order Nudibranchia, suborder Cladobranchia, and superfamily Aeolidioidea. This cosmopolitan group is composed of marine species characterized by an elongated body shape, numerous cerata arranged in dorsal rows or clusters, and a diet predominantly focused on cnidarians, especially hydrozoans.

Facelina auriculata @ Costa Brava, Spain by Pontes, Miquel

Diagnostic characters

Members of the Facelinidae family share a series of morphological characteristics, including:

  • An elongated and slender body, foot with relatively well-developed propodial tentacles.
  • Long, tubular, pointed or curved cerata, arranged in two groups, one precardiac and another postcardiac, with multiple transverse rows or grouped laterally.
  • Lamellate or smooth rhinophores, usually erect, sometimes bearing ornamentation.
  • Cleioproct anus.
  • Robust jaws with denticulate chitinous plates.
  • Radula with a single central row of teeth (uniseriate), sometimes with lateral accessory teeth.
  • Digestive gland branching into the cerata.
  • Presence of functional cnidosacs at the tip of the cerata, allowing them to store cnidocysts from their prey for defensive purposes.
  • Most feed on hydroids.

Taxonomy

The classification of Facelinidae has undergone significant revisions in recent years, mainly as a result of molecular phylogenetic studies. Since the mid-2010s, phylogenetic analyses based on mitochondrial markers (COI, 16S) and nuclear markers (H3, 18S) have shown that the traditional concept of the Facelinidae family was paraphyletic, which has led to a major restructuring of the group.

Some genera, such as Facelina and Cratena, have been redefined to reflect monophyletic clades. Other genera previously included within Facelinidae have been reassigned to different families, such as Myrrhinidae and Aeolidiidae. New genera have been described, and others have been reinstated after having been considered synonyms in the past (Samla, for instance, separated from Flabellina). The former concept of the subfamily Facelininae has been abandoned in several cladistic proposals due to a lack of monophyletic support.

This reorganization aims to reflect a more natural classification aligned with the evolutionary relationships within the group, although some aspects remain under debate among specialists.

The following genera are currently recognized as valid members of this family (WoRMS, 2024; Korshunova et al., 2017; 2020):

Facelinidae Bergh, 1889

  • Adfacelina Millen & Hermosillo, 2012
  • Algarvia García-Gómez & Cervera, 1990
  • Amanda Macnae, 1954
  • Anetarca Gosliner, 1991
  • Antonietta Schmekel, 1966
  • Austraeolis Burn, 1962
  • Bajaeolis Gosliner & Behrens, 1986
  • Burnaia M. C. Miller, 2001
  • Caloria Trinchese, 1888
  • Cratena Bergh, 1864
  • Crateninae Bergh, 1889
  • Dicata Schmekel, 1967
  • Echinopsole Macnae, 1954
  • Emarcusia Roller, 1972
  • Facelina Alder & Hancock, 1855
  • Facelininae Bergh, 1889
  • Facelinopsis Pruvot-Fol, 1954
  • Favorininae Bergh, 1889
  • Favorinus J. E. Gray, 1850
  • Hermosita Gosliner & Behrens, 1986
  • Herviella Baba, 1949
  • Herviellinae Burn, 1967
  • Janssonius Ortea & Moro, 2022
  • Jason M. C. Miller, 1974
  • Learchis Bergh, 1896
  • Moridilla Bergh, 1888
  • Myja Bergh, 1896
  • Noumeaella Risbec, 1937
  • Palisa Edmunds, 1964
  • Pauleo Millen & Hamann, 1992
  • Phidiana Gray, 1850
  • Pruvotfolia J. Tardy, 1970
  • Pteraeolidiinae Risbec, 1953
    • Pteraeolidia Bergh, 1875
  • Sakuraeolis Baba, 1965
  • Setoeolis Baba, 1965

The species from the Mediterranean Sea and nearby Atlantic included in this family are:

References

Cite this article as:

Pontes, Miquel (2025) "Facelinidae" in OPK-Opistobranquis. Published: 12/06/2025. Accessed: 27/07/2026. Available at (https://opistobranquis.info/en/?p=46890)