Family Xanthonychidae Strebel & Pfeffer, 1879

There is a single species occurring in Canada, Monadenia fidelis, which is the largest terrestrial snail in the country and a quite remarkably coloured and distinctive species. The genus Monadenia has also been placed in Helminthoglyptidae, Bradybaenidae, and its own family, Monadeniidae.

Subfamily Monadeniinae H. Nordsieck, 1987

Genus Monadenia Pilsbry, 1895

  • Monadenia Pilsbry 1895 in 1893–1895: 198; type species by original designation: Helix fidelis Gray, 1834.

Etymology. Greek: monos, one + aden,gland, a reference to the single mucus gland (Pilsbry 1939).

Subgenus Monadenia Pilsbry, 1895

Monadenia (Monadenia) fidelis (Gray, 1834)