Idiosoma sigillatum is a species of mygalomorph spider in the Idiopidae family.

[1][2] The species occurs in south-west Western Australia, in the Swan Coastal Plain and Jarrah Forest bioregions, including the Darling Scarp and Rottnest Island, in open forest habitats.

The type locality is Swan River (Perth).

[1][2] The spiders are fossorial, terrestrial predators.

They construct burrows with trapdoors in plant litter on sandy-gravel soils, with a fan of twig-lines around the entrance.