Family Xanthonychidae Strebel and Pfeffer 1880 (slug)
Gastropoda - Stylommatophora - Xanthonychidae
Parent taxon: Helicoidea according to B. Marshall et al. 2025
Sister taxa: Anguispira, Camaenidae, Elonidae, Euconulus, Geomitridae, Helicidae, Helicodontidae, Hygromiidae, Neohelix, Pleurodontidae, Polygyridae, Sphincterochilidae, Stenotrema, Triodopsis, Trissexodontidae
Subtaxa: Helminthoglyptinae
Ecology: epifaunal
Distribution:
• Hemphillian of United States (1: California collection)
• Eocene of United States (1: California)
Total: 2 collections each including a single occurrence