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

It was described in 2018 by Australian arachnologists Michael Rix and Mark Harvey.

The specific epithet dandaragan refers to the type locality.

[1][2] The species occurs in south-west Western Australia, in the Avon Wheatbelt, Jarrah Forest and Swan Coastal Plain bioregions.

The type locality is 19.5 km south of Moora, on the Dandaragan Plateau north of Perth.