Kawina Barton, 1915

Adrain, Jonathan M. & Pérez-Peris, Francesc, 2021, Middle Ordovician (Darriwilian) cheirurid trilobites from the Table Cove Formation, western Newfoundland, Canada, Zootaxa 5041 (1), pp. 1-73 : 25-26

Kawina Barton, 1915

= Kolymella Čugaeva, 1973

Type species. By original designation; Cheirurus vulcanus Billings, 1865a , from the Shallow Bay Formation ( lower Darriwilian ) of western Newfoundland, Canada (Laurentia) .

Other species. Kawina arnoldi Whittington, 1963 , Shallow Bay Formation (lower Darriwilian), Newfoundland, Canada (Laurentia); K. limbata Whittington, 1963 , Shallow Bay Formation (lower Darriwilian), Newfoundland, Canada (Laurentia); K. plana Čugaeva in Čugaeva et al., 1964, Elgenchak Formation (Darriwilian), Magadan Oblast, far eastern Russia (Kolyma-Omolon Terrane); K. spinigena Ancygin, 1977 , Karakol-Mikhailovsk Horizon (Darriwilian), Urals, Russia (Baltica); K. stougei n. sp., Table Cove Formation (Darriwilian), Newfoundland, Canada (Laurentia); K. wilsoni Ross, 1972 , Antelope Valley Formation (Dapingian), Nevada, USA (Laurentia).

Diagnosis. Glabella widest posteriorly, across middle or anterior portion of L1; librigenal lateral border strongly inflated; librigenal lateral border furrow narrow and field broad; hypostome with long anterior lobe of middle body, middle furrows weakly expressed and set far posteriorly; pygidium with three well expressed axial rings, axial furrows meeting posteriorly to fully circumscribe axis, and broad, dorsoventrally flattened, pleural spines with blunt ends; pleural spines attached to adjacent spines for much of their length.

Discussion. Restriction of Kawina to a core Middle Ordovician group sharing all of the prominent diagnostic features and transfer of some previously assigned species with question to Cydonocephalus were discussed above. Most of the species are Laurentian, but the Darriwilian K. spinigena Ancygin, 1977 , is from Baltica and shares all of the cranidial and pygidial synapomorphies of the genus.

Kawina plana Čugaeva in Čugaeva et al., 1964, type species of the monotypic Kolymella Čugaeva, 1973 , also shares the cranidial and pygidial characters of Kawina . This species is from the Elgenchak Formation (Darriwilian), Elgenchak Mountains, Magadan Oblast, far eastern Russia. The faunas of the Kolyma-Omolon Terrane contain a mix of endemics, taxa with Siberian affinity, and taxa with Laurentian affinity (see discussion of Parasphaerexochus above). Kolymella is one of the latter, as the only feature that seems to differentiate it from species of Kawina is the apparent lack of inflation of the glabella ( Fortey, 1980, p. 86). Exactly how much the glabella is dorsally inflated however, is difficult to judge, as Čugaeva ( Čugaeva et al.,1964; Čugaeva, 1973) did not illustrate any lateral or anterior views. Nevertheless, one slightly oblique photograph ( Čugaeva, 1973, pl. 10, fig. 2b) does suggest fairly low dorsal convexity. Given that this is the only point of differentiation, in the current state of knowledge we regard it as a specific autapomorphy of K. plana and consider Kolymella a junior subjective synonym of Kawina .