What is "ibexaspis"

Ibexaspis is a trilobite in the order Phacopida (family Pliomeridae), that existed during the lower Ordovician in what is now the United States. It was described by Pribyl and Vanek in 1985, and the type species is Ibexaspis quattuor, which was originally described under the genus Protopliomerops as the subspecies P. quattuor brevis by Young in 1973. The type locality was the Fillmore Formation in Utah.