Gaius villosus is a species of spider in the family Idiopidae (armored trapdoor spiders) found in Western Australia in a variety of different habitats.

[2] Originally described in 1914 as Gaius villosus by William Joseph Rainbow,[1][3] in 1957 it was transferred to Anidiops by Barbara Main[1][4] (a genus no longer recognized).

In 2017, it was returned to Gaius by Rix and others[1][5] – at the time it was the sole species in the genus,[5] although others have been added since.

[1] Number 16,[6] aged approximately 43 years at death and thought to be the longest-lived spider on record, was a female of this species.

This Idiopidae article is a stub.