The Hystricurid Trilobite Metabowmania in the Lower Ordovician (Ibexian; Stairsian) of the Great Basin, Utah and Idaho, USA

The Lower Ordovician (Stairsian; approximately lower-mid Tremadocian) trilobite genus Metabowmania Kobayashi, 1955, has previously been known with certainty only from the holotype cranidium of its type species. The discovery of four new species in upper Stairsian rocks of Utah and Idaho greatly increases knowledge of the taxon. Metabowmania is a highly distinctive and easily recognised clade, and is closely related to hystricurids such as Hillyardina Ross, 1951 and Hyperbolochilus Ross, 1951. These derived taxa and relatives are assigned to a new subfamily Hillyardininae. New species described are Metabowmania morgani and M. braggi. Two other species are apparently new, but material is inadequate for formal naming and they are reported under open nomenclature.