Trinchesia ilonae

Trinchesia ilonae Schmekel, 1968

Trinchesia ilonae by Schmekel & Portmann (1982)










































Trinchesia ilonae  Schmekel, 1968

 Classification according to Bouchet et al. (2017)
Taxonomic source: World Register of Marine Species (AphiaID: 750610).

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.


  • Cuthona ilonae (Schmekel, 1968)

Elongated and thin body, translucent white, with a maximum length of 4 mm. The rhinophores, the dorsal part of the oral tentacles, the head and the back of the body are covered with irregularly shaped white spots, which also appear, but with a more uniform distribution, forming bands on the cerata. The rhinophores are digitiform, smooth and relatively long, up to one third of the total body length, and are joined at the base. A characteristic dark pink or violet ring, bordered by transparent areas, separates the distal third of the rhinophores. Bright spots of the same color are present at the inner base of all cerata and form a few spots on the dorsal part of the body. The oral tentacles are half the length of the rhinophores. Up to 6 rows of cerata are arranged on the sides of the body, with up to 3 cerata in each row, on each side. The tail and middle part of the body do not have cerata. Each cera is shaped like a spindle, with a tappering distal end, where the white cnidosacs are found. The digestive gland is visible through the skin of the cerata, it is basally dark brown, but it becomes of a lighter color towards the distal end. The anus and nephroproct are located between the third and fourth rows of cerata on the right side of the body, near the inner cerata of the fourth row. The gonopore is located under the first row of cerata on the right side. The propodial tentacles are rounded.

The egg spawn is a spiral arranged cord forming a single whorl with white eggs with a diameter of 0.12mm. The veliger larvae hatch after 11 days and become part of the plankton. It is believed to feed on the hydrozoan Campanularia johnstoni (Urgorri & Besteiro, 1984; 1986).


  • 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.
  • Ilonae. In honor of Ilona Richter. Scientific illustrator originally from Szeged, Hungary, since 1952 she worked for the Hungarian Museum of Natural Sciences, the National Museum of Hungary, the Zoological Station of Naples, the Laboratoire Arago of Banyuls-sur-Mer and the Hungarian Academy of Sciences, where she retired in 1990. She worked for Dr. Adolf Portman of the Zoological Institute of the University of Basel and for Dr. Luise Schmekel of the Zoological Institute of the University of Münster/Westphalia, illustrating their well-known monograph “Opisthobranchia des Mittelmeeres”.

Schmekel (1968) describes the species based on specimens found in the Gulf of Naples (Italy), on the nearby islands of Ischia and Capri (Italy), as well as in Banyuls-sur-Mer (France), always among the leaves of Posidonia oceanica, between 10 and 35 meters deep. Templado (1982) captures this species at a depth of about 4 meters in Cabo de Palos (Murcia, Spain) on Posidonia  oceanica rhizomes. Urgorri & Besteiro (1986) found it in the Ría de Ferrol (Galicia, Spain) with specimens captured between 2 and 5 meters deep on red algae, Codium and Cystoseira, also between the leaves of Zostera marina. García Gómez, et al (1991) cite specimens of this species at Sagres (Portugal) at about 20 meters depth.

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


    Western Mediterranean: ★☆☆☆☆
    Eastern Mediterranean: ☆☆☆☆☆
    Atlantic Ocean: ★☆☆☆☆

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

More pictures


Further reading

Cite this article as:

Pontes, Miquel (2023) "Trinchesia ilonae" in OPK-Opistobranquis. Published: 07/12/2023. Accessed: 02/03/2024. Available at (

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