California turret spiders (Antrodiaetus riversi; superfamily Atypoidea, family Antrodiaetidae) are medium-sized mygalomorph spiders native to Northern California that construct burrows with a cork-like trapdoor made of soil, vegetation and silk. This spider's length is 13 to 18 millimetres (0.51 to 0.71 in) long, though females are larger than males.