Borealea Korshunova et al. , 2017
publication ID |
https://doi.org/10.1093/zoolinnean/zlaf057 |
publication LSID |
lsid:zoobank.org:pub:D09886E-5D7C-40D1-B86A-118A3ADE5773 |
persistent identifier |
https://treatment.plazi.org/id/03EF87FE-FFF9-FF99-FF58-FC8EFB29F9C8 |
treatment provided by |
Plazi |
scientific name |
Borealea Korshunova et al. , 2017 |
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Genus Borealea Korshunova et al., 2017 View in CoL , reinstated
( Figs 1, 2, 13; Table 5)
Korshunova et al. 2017a: 27.
Korshunova et al. 2017b: 140.
Type species: Coryphella nobilis Verrill, 1880 .
Diagnosis: Body moderately wide. Notal edge present, continuous. Cerata in continuous rows. Rhinophores wrinkled. Anterior foot corners present. Central teeth with narrow cusp compressed in different degrees with distinct denticles. Lateral teeth denticulated with attenuated process basally. Distal and proximal receptaculum seminis. Moderately long vas deferens, distinct prostate in several loops expanding into narrow, long, penial sheath. Penis narrow, tubular.
Species included: Borealea nobilis (Verrill, 1880) comb. nov. and Borealea sanamyanae Korshunova et al., 2017 comb. nov..
Remarks: Eleven Borealea nobilis and six Borealea sanamyanae formed separate sister-clades (PP = 1, BS = 100), within the common genus Borealea clade ( Fig. 13). The Borealea clade had the sister-position to the clade Coryphella , but not with high support (PP = 0.98, BS = 71; Fig. 13). The genus Borealea immediately differs from the sister-genus Coryphella by its continuous notal edge, narrow cusp of the central teeth compressed (in various degrees), lateral teeth with attenuated basal process, and non-discoid penis ( Korshunova et al. 2017a, present study). All these differences were incorrectly dismissed in Ekimova et al. (2022), but two years later, in 2024, all three species of Borealea (so far known) formed a distinct clade in Ekimova et al. (2024). In other words, the trees’ topology returned the results published in Korshunova et al. (2017a).
The genus Borealea also forms a distinct clade according to the present molecular phylogenetic analysis ( Figs 1, 2, 13). Kuzirian (1977) exhaustively studied the morphological, ecological, and nomenclatural data on Borealea nobilis based on numerous specimens collected close to the type locality. Among other details, Kuzirian (1977: 233, fig. 6) unequivocally stated that the ‘penial sac contains a large expandable preputium and the long narrow tubular penis’. However, Ekimova et al. (2022) described a broad penial sheath and lobe-shaped penis. Taking into consideration the exhaustive details and high methodological approach in Kuzirian (1977), we conclude that the penis of ‘ Borealea nobilis ’ in Ekimova et al. (2022) was incorrectly described.
Moreover, an immediately recognizable morphological feature of the genus Borealea , the compressed cusp of the central teeth (the cusp of the central teeth of Borealea , even in various degrees of compression, are readily recognizable compared to the sister-genus of Coryphella proper with distinctly non-compressed cusps in all three species) were clearly and unambiguously depicted in Ekimova et al. (2024: fig 9) for all three species of the distinct Borealea clade. While the valid genus Borealea was incorrectly synonymized based on incorrectly assessed paraphyly (see details above in the Results) two years ago in Ekimova et al. (2022), the illustrations of radula patterns in Ekimova et al. (2024: fig. 4) clearly show morphological differences between the radulae of the group that includes nobilis , sp. 1, and sanamyanae and of all other ‘ Coryphella ’ with a non-compressed cusp yet there was no mention of ‘paraphyly’ in 2024 and no indication that a new genus was necessary for the group with a compressed central tooth, not to mention that a valid genus had previously been described in Korshunova et al. (2017a) for that group. Lumping genera based on incorrect analysis and then failing to acknowledge the error, even when providing illustrations showing morphological distinctness, shows a bias toward lumping rather than a desire to follow the mosaic patterns of evolution to their fine-scale taxonomic conclusions.
Remarkably, the incorrect synonymization of the genus Borealea with ‘ Coryphella ’ further concealed the existence of (and still not properly described) hidden diversity among the true Borealea , since an undescribed species, sister to B. nobilis , was mentioned in Ekimova et al. (2024). In the present study we, for the first time, report the discovery of B. sanamyanae (initially discovered in the north-west Pacific, Korshunova et al. 2017a: 27–8, fig. 17) from the north-east Pacific (collected in Rich Passage, WA, which also matches a GenBank sequence from British Columbia), which significantly expands the range of the species and genus ( Fig. 13), thus further documenting the fine-scale diversity within Borealea . Therefore, the genus Borealea encompasses a broad range of localities in boreal waters of the Northern Hemisphere, but does not penetrate considerably into true Arctic waters. Comparison of the genus Borealea with all valid, currently included Coryphellidae genera is presented in Table 5. See also Results and Discussion.
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