Tardigrades of North America: Western Montana

Abstract

Tardigrades are an under-studied phylum of microscopic aquatic animals that inhabit the interstitial moisture in mosses and lichens. This little-known group may at times be common and abundant, but because of the unique habitat, it is often overlooked in the biodiversity of an area. This is only the second report of tardigrades in Montana. The nine genera and 20 species are all new records for west of the Continental Divide in Montana. Each species collected represents a significant range extension, expands the known biodiversity of the state, and infers the diversity of the region is far greater than yet revealed. Five pairs of species were associated with each other statistically more frequently than expected. Four of the species were also statistically associated with the lichen habitat and three with the moss. Likewise, several species of tardigrade were found in habitats on soil and rock substrates more often than expected. These glimpses into habitat selection of tardigrades offer clues to the limits of tardigrade life.