Combination of carapace length/cheliceral fixed digit length ratio 7.0-9.0; basitarsus II with mrs seta .
(Key) Cheliceral fixed digit inferior carina extends proximally at least to level of bicusp; carapace length/cheliceral fixed digit length ratio 4 .2 or more; Pectinal teeth 24/24 or more in males and 17/18 or more in females and 37 or more primary denticles (less proximal row) on pedipalp movable fingers, or if fewer pectinal teeth then either (1) dorsal metasomal setae I-IV 0,0,0,1, or (2) no mrs seta on basitarsus II boreus infragroup; Basitarsus II with mrs seta; Carapace length/cheliceral fixed digit length ratio 7 .0 or more boreus microgroup
Distribution: Rocky Mountains region westward to Pacific coastal mountains (excluding northwest coast), southern Canada southward to northern Arizona and northern Baja California Norte (excluding Mojave and Sonoran Deserts). (Haradon 1985) .
Included taxa: Paruroctonus boreus (Girard, 1854); Paruroctonus silvestrii (Borelli, 1909); Paruroctonus bantai bantai (Gertsch and Soleglad, 1966); P. bantai saratoga Haradon 1985; Paruroctonus arnaudi Williams, 1972.