Kornia Ebbighausen & Bockwinkel 2007

Genus Kornia Ebbighausen & Bockwinkel, 2007 Type species Kornia citrus Ebbighausen & Bockwinkel, 2007: 143; original designation. Diagnosis Genus of the subfamily Prionoceratinae with a spindle-shaped conch in the juvenile stage and globular conch in the adult stage. Umbilicus almost closed in stages larger than 7 mm diameter, in the juvenile stage with raised umbilical edge. Growth lines strongly curved back from the umbilical margin, forming broad and deep ventral sinus. Genus composition Central Europe (Vöhringer 1960): Imitoceras sphaeroidale Vöhringer, 1960; Kornia fibula sp. nov.; Kornia acia sp. nov. North Africa (Ebbighausen & Bockwinkel 2007): Kornia citrus Ebbighausen & Bockwinkel, 2007. Remarks The genus Kornia was introduced by Ebbighausen & Bockwinkel (2007) for very small specimens which are characterised by their spindle-shaped conch and conspicuous umbilical shape, thus differing strongly from all other known early Tournaisian ammonoids. Juvenile ammonoids with such a shape, however, occur repeatedly in the fossil record, as shown for the Late Viséan genera Goniatites de Haan, 1825 (Klug et al. 2016; Korn 2017) and Hibernicoceras Moore & Hodson, 1958 (Schmidt 1925; Korn 1988a). Kornia differs from Globimitoceras, apart from the juvenile conch morphology, in the course of the growth lines, which are almost straight in Globimitoceras are, but in Kornia they have a very broad and deep ventral sinus.Published as part of Korn, Dieter & Weyer, Dieter, 2023, The ammonoids from the Gattendorfia Limestone of Oberrödinghausen (Early Carboniferous; Rhenish Mountains, Germany), pp. 1-230 in European Journal of Taxonomy 882 on pages 37-38, DOI: 10.5852/ejt.2023.882.2177, http://zenodo.org/record/817758