This species of mite, according to several online sources, is pretty much restricted to various slug species. Where it is often seen scuttling around the mucus covered body and as can be seen from the video below, paying a special interest in the lung cavity.
We have witnessed on one occasion, but unfortunately were not recording video at the time, one slug with such an extreme infestation that at one stage it exuded a frothy excretion from its lung hole which seemed to send the mites running. Some even temporarily left the slugs body. Unfortunately for the slug, they all quickly returned.
A close relative, Riccardoella limacum, is very similar but feeds upon Snail species instead.