Idiosoma subtriste is a species of mygalomorph spider in the Idiopidae family. It is endemic to Australia. It was described in 1877 by British arachnologist Octavius Pickard-Cambridge.[1]
The species occurs in South Australia, in the Mount Lofty and Flinders Ranges, in open scrub and woodland habitats. The type locality is Adelaide.[1]
The spiders are fossorial, terrestrial predators.[1]