Calmella gaditana

Calmella gaditana (Cervera, García-Gómez, & García, 1987)

Calmella gaditana by José Carlos García Gómez










































Calmella gaditana  (Cervera, García-Gómez & F. J. García, 1987)

 Classification according to Bouchet et al. (2017)
Taxonomic source: World Register of Marine Species (AphiaID: 1048800).

Taxonomic note: The classification of the Flabellinidae had remained fairly stable until in 2017 a series of works appeared (Furfaro et al., 2017; Korshunova et al., 2017) that intended to clarify the status of the Flabellinidae family. The main objective of the paper by Furfaro et al. was to molecularly characterize the Mediterranean species while the paper by Korshunova et al. wanted to delve into the phylogenetic relationships between various members of the Flabellinidae family and the other families of aeolidaceans.
Both works were based on the combination of molecular and morphological techniques and, in fact, do not offer very different results, but differ on the size and origin of the studied samples and, mainly, on the interpretation of the results. After the appearance of the paper by Furfaro et al., many Mediterranean species of the genera Calmella, Flabellina and Piseinotecus were grouped under the common genusFlabellina, but had certain problems with some species that did not fit well with the proposed classification (e.g,Flabellina babai) , discovered that the Mediterranean and Atlantic populations ofFlabellina ischitana correspond to two different cryptic species, and noted the problems of the cryptic group formed by Calmella cavolini / Flabellina confusa / Piseinotecus gaditanus, indicating the need for further studies to clarify their status.
Curiously, these studies were being carried out practically in parallel by the group of Korshunova et al. but on a much wider sample of species that included specimens from the Arctic, North Atlantic, Pacific and Indian Oceans. This second paper confirms the polyphily of the family Flabellinidae, but the interpretation of these results becomes a real revolution for the taxonomy of the aeolidaceans, especially for the family Flabellinidae.
Both papers show that there are two well differentiated clades (groups) in the Flabellinidae: species like Coryphella pedata and similars, with cerata that come directly from the back, and species like Flabellina affinis and similars, with cerata of each group coming from a stalk or pod. Although Furfaro et al. consider the species of both clades belonging to the genusFlabellina within the family Flabellinidae, Korshunova et al. distinguishes two families: Coryphellidae and Flabellinidae sensu stricto, also creating many different genera in these families to include the species they study. Its taxonomic proposal, curiously, solves the problems found by Furfaro et al.
In a way, both papers complement to each other, although in the paper by Korshunova et al. it is evident the lack of studies on tropical flabellinid species and those from southern America and Africa, so the subject has not been settled. The proposal to create new genera to collect small groups of species, instead of multispecific genera, seems to be the trend in some of the phylogenetic works of recent years. A detailed discussion of this exciting controversy can be found at (

Calmella gaditana was originally described in the Cadiz coast (SW Spain) as Piseinotecus gaditanus (Cervera et al., 1987) mainly because its uniseriate radula, although the authors of the description already remarked its great morphological similarity with Calmella cavolini, of triseriate radula. Subsequently, a new species was described, Flabellina confusa González-Duarte, Cervera & Poddubetskaia, 2008 thanks to specimens collected in the Bay of Arcachon, on the French Atlantic coast. Morphologically F. confusa was almost identical to P. gaditanus but had a triseriate radula, so the authors considered it a cryptic species with P. gaditanus. Furfaro et al (2018, online September 2017), while studying the species of the Flabellinidae family of the Mediterranean and nearby areas, by using optical and electronic microscopy, verified that Piseinotecus gaditanus actually had a triseriate radula, with minute lateral teeth that the authors who originally described the species were not able to observe; In addition, they also verified by molecular analysis that P. gaditanus and F. confusa have a genetic distance of only 0.82%, which falls within what is considered intraspecific variability and therefore synonymize confusa with gaditanus and placed the latter species within of the genus Flabellina as F. gaditana (Cervera, García-Gómez & García, 1987). The taxonomic history of this species takes a new twist with the paper by Korshunova et al. (2017) who, by analyzing morphologically and molecularly numerous species attributed to the Flabellinidae family, move gaditana species to the Calmella genus as C. gaditana (Cervera, García-Gómez & García, 1987). Furfaro et al. (2021) review once again the ascription of the species belonging to the genus Calmella and conclude that they belong to the genus Flabellina, showing that the chromatic pattern between Flabellina cavolini and Flabellina gaditana is not a valid diagnostic character and that they can only be distinguished molecularly. Karmeinski et al (2021) return this species to the genus Calmella.


  • Flabellina confusa Gonzalez-Duarte, Cervera & Poddubetskaia, 2008
  • Flabellina gaditana (Cervera, García-Gómez & García, 1987)
  • Piseinotecus gaditanus Cervera, García-Gómez & García, 1987 (original)

The maximum reported length of this species is 11 mm, although in general the specimens measure between 5 and 8 mm in length. The body is elongated and narrow, coloured hyaline white with two reddish areas very apparent on the head that correspond to the jaws seen by transparency. Oral tentacles and rhinophores are also hyaline white but may have some opaque white spots near their end. The rhinophores are smooth. There are 5 to 7 groups of cerata on each side of the body, which contain up to 17 cerata in the oldest group of the largest specimens, in the other groups the number of cerata decreases towards the tail. The cerata of each group come out of a common basal peduncle and are relatively short and somewhat fusiform, the reddish or dark brown digestive gland is visible inside; in the cerata there are numerous opaque and irregular white spots forming a light embossing on the surface of the cerata. The apex of the cerata is hyaline white. The propodial tentacles are short and hooked.

The specimens from Cádiz (Spain) live under stones in the intertidal zone while those from Arcachon were collected in the infralittoral, up to 14 m deep. In Catalonia (Spain), they are found in shaded rocky walls with abundance of algae and hydrozoans. The spawn is a corrugated cord about 5 mm long and 0.15 mm wide with white eggs inside oval capsules (Cervera et al., 1986), which is generally laid on hydrarian colonies such as Eudendrium (González-Duarte et al. 2008).


  • Calmella small Calma.
  • Gaditana. From Latin “Gades”, Roman colony that became the actual city of Cádiz (Spain). The first specimen of the species was described on the coast of Cádiz.

This species is known from the coasts of Cádiz (SW Spain), Portugal, Canarias (Cervera et al., 2004), the Balearic Islands, the Bay of Arcachon (González-Duarte et al., 2008) and in the Cape Verde Archipelago (Ortea et al., 1993). The only reports for the Mediterranean Sea correspond to the observations made in different locations of the catalan Costa Brava (NE Spain), where it is relatively abundant (Ballesteros et al., 2016), the Balearic islands, in Sardinia and in the Adriatic sea. Due to similarity with C.cavolini existing references should be revised.

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

Similar species
Calmella cavolini, very similar. They can only be separated by a molecular analysis.


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

This chart displays the monthly observation probability for Calmella gaditana based on our own records.



More pictures


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Further reading

Cite this article as:

Ballesteros, M., Madrenas, E. & Pontes, M. (2023) "Calmella gaditana" in OPK-Opistobranquis. Published: 17/05/2012. Accessed: 14/04/2024. Available at (

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