Gastropoda - Prosobranchia - Orthonematidae
Synonym: Geolcomia Licharev 1975
Full reference: F. B. Meek and A. H. Worthen. 1862. Description of new Paleozoic fossils from Illinois and Iowa. Proceedings of the Academy of Natural Sciences, Philadelphia 13:128-148
Parent taxon: Orthonematinae according to P. Bouchet et al. 2005
Sister taxa: Spirocyclus, Yochelsonistylus
Subtaxa: Orthonema amissidecoris, Orthonema ascensus, Orthonema borovskensis, Orthonema carbonaria, Orthonema cochleoides, Orthonema frequens, Orthonema hulusitaiensis, Orthonema illineatus, Orthonema inornatum, Orthonema knighti, Orthonema liratum, Orthonema marvinwelleri, Orthonema nakazawai, Orthonema nebrascense, Orthonema paedice, Orthonema panxianensis, Orthonema paulum, Orthonema paxillus, Orthonema pygmaeum, Orthonema rectimurum, Orthonema salteri, Orthonema sayrei, Orthonema semiornatum, Orthonema silinae, Orthonema simplex, Orthonema socorroense, Orthonema striatonodosum, Orthonema strigatum, Orthonema subtaeniatum, Orthonema telescopiforme, Orthonema tirusum, Orthonema tricingulatum, Orthonema youngianum
Ecology: epifaunal