Fjordia chriskaugei Korshunova, Martynov, Bakken, Evertsen, Fletcher, Mudianta, Saito, Lundin, Schrödl & Picton, 2017
Class: Gastropoda Cuvier, 1797
Subclass: Heterobranchia J.E. Gray, 1840
Clade: Euthyneura Spengel, 1881
Superorder: 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: Coryphellidae Bergh, 1889
Genus: Fjordia Korshunova, Martynov, Bakken, Evertsen, Fletcher, Mudianta, Saito, Lundin,
Schrödl & Picton, 2017
Species: Fjordia chriskaugei Korshunova, Martynov, Bakken, Evertsen, Fletcher, Mudianta, Saito, Lundin,
Schrödl & Picton, 2017
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/).
The largest specimens of this species can reach 45 mm in length. The color of the body is translucent white, with the pink or cream main viscera seen by transparency. There is a fine white line along the middle area of the back and something in a zig-zag, and also a white line on both sides of the body below the insertion of the ceratas. The dorsal midline and the lateral lines join in the tail. Oral tentacles and rhinophores are of the same color as the body, both having an opaque white line that runs through the dorsal area, joining the lines of both palps on the head and merging with the dorsal line at the base of the rhinophores, which are smooth. There are 8-10 ceratal groups in the larger specimens, only the first group is clearly differentiated from the others. Each group of ceratas originates from a somewhat expanded area of the body (notal margin). The first group having more than 20 ceratas whose size increases from the most anterior and lateral to the more posterior and dorsal. The second group (postcardiac) also has numerous ceratas, clearly decreasing the number in the other groups. The more developed ceratas are long, thin and semitransparent, showing inside the red-orange digestive gland, highlighting also the white lines or continuous along the surface of the cerata. The apex of the ceratas is semitransparent and has an apparent cnidosac. The foot is relatively narrow and semi-transparent and has a pair of well-developed triangular propodial palps that have a white opaque line along their upper face.
It is a species that lives between 20-40 m depth, where its food, the athecate hydrozoan Tubularia indivisa, is found, although juveniles may possibly feed on Eudendrium or other athecate hydrozoans (Korshunova et al., 2017). The egg mass is a narrow cord arranged irregularly with white or slightly pink eggs.
- Fjordia, derived from Norwegian “fjord” because the type locality of Fjordia lineata is Oslofjord, and it is also very common at Gulen, in the Sognefjord, from where many samples studied by Korshunova et al. (2017) come from.
- Chriskaugei. In honour of Christian Skauge (Gulen Dive Resort and Scubapixel), who first noticed the
heterogeneity of the traditional F. lineata in the field in Norway.
Given the confusion that may have existed in the past between this species and F. lineata, until now the distribution data with precision are limited to the coasts of northern Europe (Norway, Ireland and Great Britain). There are some observations in the area of the Strait of Gibraltar (M. Chacón, com, pers.) attributed to F. chriskaugei that it would be necessary to confirm, as it would be verified that its distribution area is much larger than previously thought.
| : 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: Fjordia chriskaugei
- We have not yet published references for Iberian coasts of: Fjordia chriskaugei.
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