worldwide, >10,000 described spp.(1)
and many more undescribed (estimated 80,000 spp., based on known degrees of endemism), arranged in 2 subclasses, 16 orders, and 145 families; ca. 914 described spp. in 217 genera of 52 families (of which 17 are endemic to NA, and 7 are non-native) inhabit the US and Canada, but hundreds more await description particularly in the families Glomeridae, Parajulidae, Atopetholidae, Cleidogonidae, Trichopetalidae, Striariidae, Polydesmidae, and Nearctodesmidae(2)(3)
Classification adapted from(2)
. Taxa not yet in the guide are marked (*), non-native taxa are in brackets.