Fjordia lineata

Fjordia lineata (Lovén, 1846)

Fjordia lineata by Enric Madrenas

Taxonomy
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: Coryphellidae Bergh, 1889
Genus: Fjordia Korshunova, Martynov, Bakken, Evertsen, Fletcher, Mudianta, Saito, Lundin, Schrödl & Picton, 2017
Species: Fjordia lineata (Lovén, 1846)

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/).

Synonyms

  • Aeolis argenteolineata Costa A., 1866
  • Aeolis lineata Lovén, 1846
  • Coryphella lineata (Lovén, 1846)
  • Flabellina lineata (Lovén, 1846)

Description
Mediterranean specimens of this species usually measure between 15 and 30 mm in length, although in northern Europe it has been cited that they could reach 50 mm in total length. The body is whitish and semi-transparent, it is possible to see the cream coloured viscera through the integument. The specific name refers to the thin opaque white lines on the back and sides of the body; the dorsal line runs through the middle of the back, from the last cerata up to the head, passing between the bases of the rhinophores and then forking forward to the back of the oral tentacles. The lateral lines run below the insertion of the groups of cerata and meet in the tail. Oral palps and rhinophores are roughly the same length, and they are also whitish and semitransparent; along the dorsal side of the rhinophores a thin opaque white line is observed. The tip of the rhinophores is opaque white. The eyes are very visible and are located in the back of the base of the rhinophores. The cerata are gathered in 5-8 groups, depending on the size of the specimens. The first two groups have two rows of cerata and the remaining groups only one. The cerata are long, thin, semitransparent and tappered. The anterior and posterior areas of the cerata have an opaque white line, sometimes discontinuous; the digestive gland within the cerata can be orange, red or brown. The cnidosacs are whitish and located in the tip of the cerata, in this species it has an opaque white line or spots. The foot is wide and semitransparent and in its anterior zone has two well-developed triangular propodial palps.

Biology
F.lineata is a very active species that usually lives in dimly lit rocky walls with an abundance of food, hydroids as Tubularia indivisa, Sarsia eximia, Hydallmania falcata and Sertularia argentea in European Atlantic waters, while in the Mediterranean seems to be feed on polyps of the genus Eudrendrium, like other members of the family. The spawn is laid on top of the same colonies of hydrozoans it feeds on, and it composed of a flat spiral wound cord filled with whitish or slightly pink eggs of about 75 microns in diameter (Schmekel & Portmann, 1982).

Etymology

  • 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.
  • Lineata. Refers to the fine white opaque lines running along the dorsum and sides of the animal’s body.

Distribution
This species is distributed from northern Europe (Norway, within the Arctic Circle), North Sea, French Atlantic coasts and the Iberian Peninsula to the Mediterranean Sea. In the Iberian Peninsula it has been cited in the Portuguese coast, the area the Strait of Gibraltar, the Levantine coast, Catalonia and the Balearic Islands. In the Catalan coast it has been observed, among other locations, in Illa Plana (Llançà) L’Escala, Illes Medes, Begur and Tossa de Mar.

Known georeferenced records of the species: Fjordia lineata
Sources:
: OBIS
: GROC 2010-2011
: Enric Madrenas
: João Pedro Silva
: Bernard Picton
: GBIF.ORG
: OPK
: VIMAR
: Manuel Ballesteros.
: M@re Nostrum
: Altres fonts
: Marine Regions

References for the species: Fjordia lineata

    Portugal: Calado and Urgorri (1999), Calado et al. (1999). Gibraltar: García-Gómez (1982, 2002), García-Gómez et al. (1989), Wirtz and Debelius (2003). Levante: Fez (1974), Marín and Ros (1987), Templado, Luque and Moreno (1988). Catalunya: Ros (1975), Ballesteros (1980, 1985). Todas las citas como Coryphella. Baleares: Ballesteros (1981a).

    General: Brown & Hunnam, 1976:45; Brown & Picton, 1979:19; Cattaneo-Vietti, Chemello, & Giannuzzi-Savelli, 1990:167[P]; Farran, 1909:7; Hoffmann, 1926:20; Krause, 1897:99; Loyning, 1922:32, 91; 1927:260; Nordsieck, 1972:72; Odhner, 1939:59; Perrone, 1986a:34; Picton & Morrow, 1994:94[P]; Pruvot-Fol, 1954b:421; Riedl, 1970:432; 1983:325; Roginskaya, 1962:95; Schmekel, 1970:141; Schmekel & Portmann, 1982:185[P]; Swennen, 1987:40; Thompson, 1976a:[P]; 1988:252[P]; Thompson & Brown, 1976:146[P]; 1984:111[P]; Tiberi, 1880:234; Trinchese, 1881:99; 1881a:99; Vayssiere, 1888d:73; 1913a:290; Vicente, 1963a:178; 1967:161; Walton, 1908:233 as Coryphella lineata

    Sources: Cervera et al., 2004, Ballesteros, 2007 & 2016, McDonald, 2006 and other sources.

Abundance

    Western Mediterranean:
    Eastern Mediterranean:
    Atlantic Ocean:
This chart displays the observation probability for Fjordia lineata based on our own records.

More pictures

Bibliography

Further reading

Cite this article as:

Ballesteros, Manuel, Enric Madrenas, Miquel Pontes (2012-2018) "Fjordia lineata" in OPK-Opistobranquis, Published: 17/05/2012, Accessed: 18/01/2018 at (https://opistobranquis.info/en/Por6g)

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