Paraflabellina ischitana (Hirano & Thompson, 1990)
Class: Gastropoda Cuvier, 1797
Subclass: Heterobranchia J.E. Gray, 1840
Clade: Euthyneura Spengel, 1881
Clade: Nudipleura Wägele & Willan, 2000
Order: Nudibranchia Cuvier, 1817
Suborder: Dexiarchia Schrödl, Wägele & Willan, 2001
Infraorder: Cladobranchia Willan & Morton, 1984
Parvorder: Aeolidida Odhner, 1934
Superfamily: Flabellinoidea Bergh, 1889
Family: Flabellinidae Bergh, 1889
Genus: Paraflabellina Korshunova, Martynov, Bakken, Evertsen, Fletcher, Mudianta, Saito, Lundin,
Schrödl & Picton, 2017
Species: Paraflabellina ischitana Hirano & Thompson, 1990
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. We hope to see new papers expanding the knowledge on the aeolidaceans soon. A detailed discussion of this exciting controversy can be found at (https://opistobranquis.info/en/flabellinidae/).
- Flabellina ischitana Hirano & Thompson, 1990
This species of aeolidacean can reach a size of up to 25 mm long. The body color is homogeneous pink or purple-violet except on the tips of rhinophores and oral tentacles, which are white, and the cerata, semitransparent and inside which it can be seen the red, orange or brown digestive gland, depending on the specimens. The rhinophores have from 12 to 19 thin circular lamellae. In larger specimens there can be up to 9 groups cerata on each side of the back, generally well separated from each other. The cerata of each group come from a common stalk of the same color of the body, which can be further divided in 2 to 3 secondary stalks in the groups cerata located to the front of the animal. The cerata are thin and have a whitish sharp tip, where the cnidosac can be seen. The genital and anal orifices are located on the right side of the body, the genital pore located slightly before the first ceratal stalk and the anal pore somewhat ahead of the second group of cerata. The foot is narrow, of the same color of the body and, with two small triangular propodials tentacles in the front side. The tail is short and narrow.
This is an active aeolidacean often found in shallow water, where its food, the athecate hydrozooan Eudendrium (E. racemosum, E. glomeratum) lives, but it has also been observed down to a depth of 35 m (Hirano & Thompson, 1990). It can share food and substrate with Flabellina affinis, a somewhat larger species with which it can easily be confused. Cervera et al. (1998) indicate the main differences between these two species. The spawn of P. ischitana is shaped like a thick cord arranged in irregular loops containing pink eggs about 70 microns in diameter.
- Paraflabellina, from Greek παρα (=contiguous) and Flabellina, in reference to its external similitude to the species of the genus Flabellina, despite molecular disparate results.
- Flabellina. Diminutive of Latin “flabellum”, fan.
- Ischitana. From the island of Ischia, in the Tirrenian Sea, in the gulf of Naples; where this nudibranch was first cited.
P. ischitana is a southern European species living both in the Eastern and Western Mediterranean basins. In the Iberian Peninsula it has been found in Portugal, the Strait of Gibraltar and all along the Mediterranean coast. In Catalonia it is a relatively common species which is recorded in different localities of the Costa Brava such as Cadaques, Cala Aiguablava (Begur), L’Escala and Tossa de Mar.
| : OBIS|
: GROC 2010-2011
: Enric Madrenas
: João Pedro Silva
: Bernard Picton
| : OPK|
: Manuel Ballesteros.
: M@re Nostrum
: Altres fonts
: Marine Regions
References for the species: Paraflabellina ischitana
- Portugal: Ortea and Espinosa (1998), Calado et al. (1999, 2005), Wirtz and Debelius (2003).
Andalucía (Atl.): Cervera, López-González and García-Gómez (1998).
Gibraltar: Cervera, López-González and García-Gómez (1998).
Andalucía (Med.): Sánchez Tocino, Ocaña and García (2000a), Ocaña et al. (2000).
Catalunya: Ballesteros (datos no publicados) [Cap Falcó, Punta del Gat, Punta del Bisbe de Roses, Tossa de Mar], M@re Nostrum [Cala Rovellada (Colera) 5/2006, Cap Ras (Llançà) 11/1998, Bau de S’Arnella (El Port de la Selva) 6/2000].
General: Cattaneo-Vietti, Chemello, & Giannuzzi-Savelli, 1990:161[P]; Parent, 1994:211[P]
Sources: Cervera et al., 2004, Ballesteros, 2007 & 2016, McDonald, 2006 and other sources.
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