Trinchesia genovae

Trinchesia genovae (O’Donoghue, 1929)

Trinchesia genovae by Enric Madrenas










































Trinchesia genovae  (O'Donoghue, 1926)

 Classification according to Bouchet et al. (2017)
Taxonomic source: World Register of Marine Species (AphiaID: 1037407).

Taxonomic note: The phylogenetic analyses performed by Cella et al. (2016) revealed that the traditional Tergipedidae family is polyphyletic and belongs to a larger monophyletic clade including members of the traditional families Eubranchidae, Fionidae and Calmidae; this was an unexpected result, since the validity of these taxa and their distinctness from the Tergipedidae was never questioned before. They proposed to join the families Tergipedidae, Eubranchidae, Calmidae and Fionidae under the name of Fionidae. Within Fionidae, obtained results demonstrated the need of developing a new classification as previous classifications (for instance, separating Catriona, Cuthona and Trinchesia as distinct taxa) were inconsistent with the resulting phylogeny. Analyses also recover a clade (Tenellia) that includes all members of the genera Tenellia, Trinchesia, Phestilla, Catriona and the majority of described and undescribed Cuthona species. New genera Rubramoena, Abronica and Tergiposacca are proposed to group other species. This molecular study also suggests that Fionidae is rich in cryptic species complexes, difficult to separate by traditional taxonomic characters, and a great previously undetected species diversity.
A few months later Korshunova et al. (2017) take up the study of the phylogeny of the Tergipedidae and using not only molecular data but also morphological and ontogenetic data they severely criticise the work by Cella et al. (2016), proposing to reinstate the families Calmidae, Eubranchidae, Fionidae, Tergipedidae, Cuthonidae, Cuthonellidae and Trinchesiidae, the latter being the most abundant in specific taxa. They also reinstate the genera Catriona, Diaphoreolis, Phestilla and Trinchesia that in the paper by Cella et al. (2016) had been included in the genus Tenellia. Korshunova et al. also describe a new genus, Zelentia that includes Z. pustulata (type species Eolis pustulataAlder & Hancock, 1854), Z. fulgens (MacFarland, 1966) and a new species from the Barents Sea, Z. ninel, indicating important p-distances among the three species (between 10.49% and 13.83%). All previous genera, Korshunova et al. (2017) consider them within the family Trinchesiidae. They also question the validity of the Rubramoena genus of Cella et al.
The position of WoRMS is conservative, maintaining the families Cuthonidae, Calmidae, Cuthonellidae, Eubranchidae, Fionidae, Pseudovermidae, Tergipedidae and Trinchesiidae within the superfamily Fionoidea. The European species that, until recently, were considered as Cuthona, WoRMS considers them within the genus Trinchesia, as T.albopunctata, T.caerulea, T.foliata, T.genovae, T.granosa, T.ilonae, T.miniostriata and T.ocellata. Rubramoena is also considered a valid genus in WoRMS. These opinions are those that we accept in OPK while no other more conclusive data are available.


  • Cratena genovae O’Donoghue, 1929
  • Cuthona genovae (O’Donoghue, 1929)
  • Tenellia genovae (O’Donoghue, 1929)

It is a small species that can reach 9-10 mm in length. The background color of the body is yellowish in many areas but this color is masked by an opaque white iridiscent pigment, especially in the dorsum, the sides of the body and the back of the head. In some specimens there may also be a diffuse bluish pigment. A very apparent yellow stripe runs through the middle back of the body, almost from head to tail. There are orange bands on the sides of the head. The oral tentacles are semi-transparent and short and their tips are orange. The rhinophores are also semitransparent but its surface is iridescent white and usually there is an orange subapical band; in the lower third of the rhinophores, the absence of white or orange pigment forms a narrow band that is darker than the rest of rhinophore. The eyes are at the base and slightly behind the rhinophores. There are 4-5 groups of cerata on each side of the body, the first one consisting of three rows of cerata, the other groups have a single row. The cerata are slightly fusiform, quite narrow at the base and have a pointed tip. The color of the digestive gland in the cerata is dark brown and it looks granular although this colour is masked by the rather dark iridescent blue pigment of the anterior face surface. The apex of the cerata is semitransparent and has 1 or 2 circular bands coloured cream. The foot is transparent and is slightly broadened on the anterior zone, but without forming propodial palps.

Because of its small size, this species tends to be unnoticed among the algae and hydrarians where it is commonly found, on little illuminated rocky walls. It feeds on hydrarians of the genus Obelia, Dynamena, Halecium and Sertularella. The spawn is a cord coiled in a single turn containing white eggs about 100 microns in diameter.


  • Trinchesia. In honor of Professor Salvatore Trinchese (1836-1897), Italian opisthobranchiologist, Professor of Zoology at Bologna University and successor of Paolo Panceri as Professor of Comparative Anatomy at the University of Napoli.
  • Genovae refers to the city of Genoa (Italy)

It is a species reported in all European Atlantic and Mediterranean coasts. American reports of this species should be confirmed. In the Iberian Peninsula it has been found in all coastal areas of Spain and Portugal, also in the Balearic and Canary islands. In Catalonia it has been reported in various localities of the Costa Brava: Cadaques, Begur, L’Escala, Llafranc, Tossa de Mar, Lloret, Blanes, Mataro and L’Ametlla de Mar.

Known georeferenced records of the species: Trinchesia genovae
: GROC 2010-2011
: Enric Madrenas
: João Pedro Silva
: Bernard Picton
: Manuel Ballesteros.
: M@re Nostrum
: Altres fonts
: Marine Regions

References for the species: Trinchesia genovae

Similar species
Trinchesia foliata, similar in size and with similar orange dorsal lines, but without the mid-dorsal yellow line or the yellow bands of the cerata.


    Western Mediterranean:2 out of 5 stars
    Eastern Mediterranean:1 out of 5 stars
    Atlantic Ocean:1 out of 5 stars

This chart displays the monthly observation probability for Trinchesia genovae based on our own records.



More pictures


Further reading

Cite this article as:

Ballesteros, M., Madrenas, E. & Pontes, M. (2021) "Trinchesia genovae" in OPK-Opistobranquis. Published: 17/05/2012. Accessed: 27/10/2021. Available at (

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