Tetralichine trilobites from the Upper Ordovician of Oklahoma and Virginia and phylogenetic systematics of the Tetralichini

New material, including a complete exoskeleton, from the Bromide Formation of Oklahoma, allows a complete evaluation of Probolichas Phleger, 1936 and necessitates a quantitative revision of the lichid tribe Tetralichini Phleger, 1936. A strict consensus tree of nine equally parsimonious trees generated from a branch and bound analysis indicates that the genus Probolichas is monophyletic, and should no longer be restricted as synonymous with, or as a sub-clade of Amphilichas Raymond, 1905. The genus ApatolichasWhittington, 1963 is revised as a synonym of Amphilichas, and the Tetralichini is defined as clade with three genera: Amphilichas, Probolichas, and Lyralichas Weber, 1948. Probolichas kristiae from the Bromide Formation and Amphilichas effnensis from the Effna Formation of Virginia are new species.