Trilobita - Agnostida - Agnostidae
Alternative spelling: Acmarhacis
Synonym: Cyclagnostus Lermontova 1940
Parent taxon: Agnostidae according to H. B. Whittington et al. 1997
Sister taxa: Acutatagnostus, Agnostardis, Agnostus, Ammagnostus, Biciragnostus, Connagnostus, Eurudagnostus, Formosagnostus, Glyptagnostus, Gymnagnostus, Hadragnostus, Homagnostus, Idolagnostus, Innitagnostus, Ivshinagnostus, Kormagnostella, Kormagnostus, Leiagnostus, Lotagnostus, Micragnostus, Neoagnostus, Oncagnostus, Oxyagnostus, Phalagnostus, Proagnostus, Quadrahomagnostus, Strictagnostus, Trilobagnostus
Subtaxa: Acmarhachis acuta, Acmarhachis apicula, Acmarhachis karatauensis, Acmarhachis kindlei, Acmarhachis longispinus, Acmarhachis punctatus, Acmarhachis typicalis, Acmarhachis whittingtoni
Ecology: slow-moving nektonic suspension feeder