Johnsoniana, Poletaev, 2024

Poletaev, Vladyslav, 2024, New and revised taxa of Carboniferous spiriferides (Brachiopoda, Spiriferida) from the Donets Basin (Ukraine) and South Urals (Russia), European Journal of Taxonomy 968, pp. 132-155 : 146

Genus Johnsoniana nom. nov.

Type species

Spirifer oceani d’Orbigny, 1849 ; original designation (by monotypy).

Diagnosis

Shells small to medium-sized, pentagonal or trapezoidal outline with equibiconvex profiles; ventral interarea triangular, medium high, concave only under apex, apsacline to catacline with denticulate hinge line equal to the width of shell; cardinal extremities acute but not mucronate; delthyrium narrowly elongate, triangular, high, partly covered by pseudodeltidium; shallow ventral sulcus and median depression on fold clearly limited by coarse rounded opposite plica, divided each valve into three depressed areas; flank plications absent; anterior commissure subrectilinear. Surface smooth or with concentric wrinkles and obscure irregular radial striae (10–12 per mm). In ventral valve strong deltirial ridges, boarding delthyrium, septum and dental plates absent; in dorsal valve short base of crural plate and flat ctenophoridium. Shell substance impunctate.

Stratigraphic and geographic range

Western Europe ( Belgium), Russia, Urals (Bashkortostan); Mississippian, from the Late Tournaisian to Viséan (late Warnantian or late Asbian).

Included species

Type species only.