Fjordia, Korshunova, Tatiana, Martynov, Alexander, Bakken, Torkild, Evertsen, Jussi, Fletcher, Karin, Mudianta, I Wayan, Saito, Hiroshi, Lundin, Kennet, Michael Schroedl, & Picton, Bernard, 2017

Korshunova, Tatiana, Martynov, Alexander, Bakken, Torkild, Evertsen, Jussi, Fletcher, Karin, Mudianta, I Wayan, Saito, Hiroshi, Lundin, Kennet, Michael Schroedl, & Picton, Bernard, 2017, Polyphyly of the traditional family Flabellinidae affects a major group of Nudibranchia: aeolidacean taxonomic reassessment with descriptions of several new families, genera, and species (Mollusca, Gastropoda), ZooKeys 717, pp. 1-139 : 25

Fjordia gen. n. Figs 21, 22, 23, 24

Type species.

Aeolis lineata Lovén, 1846.

Etymology.

After the Norwegian word “fjord” because of the type locality of the Oslofjord and also this is a very common species at Gulen at the mouth of the Sognefjord, where many of the studied materials come from.

Diagnosis.

Body narrow. Notal edge present, moderately reduced, discontinuous. Cerata in several groups. Rhinophores smooth, similar in length or shorter than oral tentacles. Anterior foot corners present. Rachidian teeth with non-compressed cusp and distinct denticles. Lateral teeth denticulated with attenuated process basally. Separated distal and proximal receptaculum seminis. Vas deferens very short, expanding to a broad penial sheath. Penis broad, lobe-shaped.

Species included.

Fjordia browni (Picton, 1980), comb. n. (original description in Picton 1980) (Fig. 22), Fjordia (?) capensis (Thiele, 1925), comb. n. (original description in Thiele 1925), Fjordia lineata ( Lovén, 1846), comb. n. (original description in Lovén 1846), Fjordia chriskaugei sp. n., Fjordia (?) insolita (Garcia-Gomez & Cervera, 1989), comb. n. (original description in Garcia-Gomez and Cervera 1989).

Remarks.

According to combined morphological and molecular evidence, the traditional species Coryphella lineata was found to be a very heterogeneous species complex. This complex includes at least five species, which are clearly separated into two major clades according to molecular analysis (Figs 1, 2) and by the morphological data (presence or absence of continuous notal edge). According to these data two new genera are proposed for the former C. lineata complex. First is the group of narrow-bodied coryphellids with discontinuous notal edge which included the proper C. lineata , C. browni , and a new species (see below); it is named as the new genus Fjordia gen. n. The second group with a continuous notal edge includes two new species and the previously enigmatic species Coryphella borealis Odhner, 1922 (not to be confused with Chlamylla borealis Bergh, 1886, see above), which represents specimens wrongly identified as Coryphella gracilis in a barcoding project by Barco et al. (2016) and which have been fully investigated for the first time in the present studies (Fig. 25) including both morphological and molecular study (Figs 1, 2). Our sequences of real C. borealis are identical to the above-mentioned wrongly identified C. gracilis from GenBank. Real C. gracilis has very different morphological features and this species is recovered in a completely different clade in our molecular tree (Figs 1, 2). These two clades, clearly delineated by morphology and molecular analysis are therefore named Fjordia gen. n. (with discontinuous notal edge) and Gulenia gen. n. (with continuous notal edge).

In this study it is also confirmed for the first time that the enigmatic C. borealis Odhner, 1922 belongs to the genus Gulenia according to integrative morphological and molecular studies (Figs 1, 2, 25). Both new genera share a similar reproductive system with a very short vas deferens and wide penis (Fig. 21), that imply a common ancestry, confirmed by molecular data (Figs 1, 2). Fjordia browni (Fig. 22) unlike other species of the genus Fjordia does not possess both dorsal and lateral white lines, but the presence of rudimentary notal edges, shape of the radular teeth, short vas deferens, and broad penial lobe are consistent with F. lineata . Molecular results place this species as sister to Fjordia chriskaugei sp. n. and in a clade where other members have dorsal and lateral white lines. All studied specimens from the Gulen region demonstrate a high degree of uniformity both in body shape and colour. Originally described from the UK where specimens were significantly smaller than exemplars from Gulen, nevertheless it keeps all essential diagnostic characters; discontinuous notal ridge, complete absence of the white lines, and radular pattern. The specimens from Gulen measured up to 100 mm in length. According to the morphological data, we included two more species (the South African Coryphella capensis and western Mediterranean Flabellina insolita ) in the genus Fjordia , but further molecular data are necessary to confirm this.