Aliatypus

Aliatypus is a genus of North American folding trapdoor spiders first described by C. P. Smith in 1908.[2] They resemble members of Ctenizidae in morphology and behavior, but this is due to convergent evolution rather than direct relation.[3] They are most closely related to members of Antrodiaetus, which build collar doors. It is likely that the shift from using collar doors to using trapdoors is what allowed them to survive in hot, dry conditions where their closest relatives could not.[4]

Aliatypus
Female A. torridus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Class:	Arachnida
Order:	Araneae
Infraorder:	Mygalomorphae
Family:	Antrodiaetidae
Genus:	Aliatypus Smith, 1908[1]
Type species
A. californicus (Banks, 1896)
Species
14, see text

Often found in roadside banks or ravines, they build a burrow perpendicular to the surface with a wafer-like trapdoor entrance to catch prey. Burrows are often clustered together, sometimes quite densely in more favorable positions.[4]

They are native to the western United States,[3] where the complex landscape creates pockets of isolated species limited to small regions. As one of the most abundant genera of trapdoor spiders in California, it is argued that their sedentary lifestyle and limited dispersal could benefit studies in the biogeography of California and the surrounding regions.[5]