29, see text Idiosoma is a genus of Australian armoured trapdoor spiders that was first described by Anton Ausserer in 1871.

[3] The skin of their abdomen is hardened, with a flattened end and deep grooves running along the sides.

This phenomenon is called phragmosis and occurs in perfection in the spider genus Cyclocosmia (Ctenizidae).

[5] Females of the black rugose trapdoor spider (Idiosoma nigrum) can grow up to 30 millimetres (1.2 in) long.

The spiderlings hatch in mid-summer, and stay inside the burrow until early winter, when the weather becomes more humid.