Gulenia Korshunova

Gulenia Korshunova View in CoL et al, 2017, reinstated

( Figs 1, 2, 13; Table 5)

Korshunova et al. 2017a: 34.

Type species: Gulenia orjani Korshunova et al., 2017 .

Diagnosis: Body moderately wide. Notal edge present, continuous. Cerata in continuous rows. Rhinophores smooth to wrinkled. Anterior foot corners present. Central teeth with non-compressed wide cusp and distinct denticles. Lateral teeth denticulated with attenuated process basally. Distal and proximal receptaculum seminis. Vas deferens very short, expands into a broad penial sheath, prostate indistinct. Penis broad, lobe-shaped.

Species included: Gulenia borealis ( Odhner, 1922) comb. nov., Gulenia monicae Korshunova et al., 2017 comb. nov., and Gulenia orjani Korshunova et al., 2017 comb. nov. Detailed morphological data in Korshunova et al. (2017a).

Remarks: Gulenia borealis , G. monicae , and G. orjani cluster with the highly-supported Gulenia clade and form a sister-group to the Fjordia clade ( Figs 1, 13). The genus Gulenia differs from the phylogenetically sister-genus Fjordia by a continuous notal edge, a notable ancestral feature especially pronounced in the species Gulenia borealis (original description in: Odhner 1922). For the discussion and justification of the ancestral status of this character see Korshunova et al. (2017a), and Martynov et al. (2020). Gulenia , along with a few other coryphellid genera, is partly similar to members of the family Paracoryphellidae , which is otherwise very different and invariably forms a distinct, compact molecular phylogenetic group (see Synopsis above; Figs 1, 13). During our extensive field work in the course of more than seven years in Gulen, Norway (the type locality of two of the Gulenia species), we observed hundreds of Gulenia specimens, but never saw any specimen with a discontinuous notal edge. It is potentially possible that a discontinuous notal edge is present in juvenile specimens, or in specimens living in some special environmental conditions (e.g. in Denmark and Sweden), but otherwise the presence of a continuous notal edge represents a stable and well-diagnosable feature in subadult and adult Gulenia . Furthermore, the central teeth of the genus Gulenia have a stronger cusp than in Fjordia . There are no other coryphellid genera that present the set of characters as found in the genus Gulenia . According to all molecular phylogenetic data, the sister-genera Gulenia and Fjordia invariably form distinct, stable, separate clades. The crucial importance of fine-scale taxonomic differentiation at the generic level is especially well illustrated by the genus Gulenia , since it includes some of the most morphologically difficult to distinguish, hidden diversity within the family Coryphellidae , represented by the species Gulenia monicae and Gulenia orjani ( Korshunova et al. 2017a) . Without fine-scale taxonomic differentiation, all these differences would be obscured under the pan-lumping concepts of ‘ Flabellina ’ or ‘ Coryphella ’. Comparison of the genus Gulenia with all valid, currently included Coryphellidae genera is presented in Table 5.