The open-holed trapdoor spiders of the Teyl damsonoides-group (formerly included in the now synonymized genus Merredinia Main, 1983) are revised, and 20 new species are described from the biodiversity hotspot of south-western Western Australia. The only previously described species, T. damsonoides (Main, 1983), is further re-described and re-illustrated, and molecular data from seven genes for a subset of nine species are analyzed using Bayesian methods. The damsonoides-group of Teyl are unusual for their stunning bi-colored appearance and the bowed morphology of the male metatarsus I, and we here document the known diversity and biology of these little-known spiders.