This spider is a species within the genus Titiotus, which is native to California. The genus is covered in “A Revision of the Endemic Californian Spider Genus Titiotus Simon (Araneae, Tengellidae), by Norman I. Platnick and Darrell Ubick. Based on their distribution map, our local species are Titiotus californicus and Titiotus gertschi.
Titiotus superfically looks like a brown recluse spider, or desert recluse spider, but isn’t. Titiotus has eight eyes, whereas brown recluse-type spiders have only six. Due to its prominent violin marking and large size, Titiotus is one of the most commonly reported species. Do not worry, as the venom of these spiders is not toxic to people. Rick Vetter told me, via a personal communication, of a medical student who was bitten, and the bite had “almost no effect.”
A quote from the Platnick and Ubick paper: “At lower elevations, including the Coast Ranges, Titiotus species occur mostly in forests, especially oak and mixed evergreen, but also in rocky grasslands. These spiders are also strongly cavernicolous; almost half of the known species are recorded from caves, where they may be quite abundant. For example, in Speleogen Cave (Calaveras County, Aug. 8, 1986, D. Ubick) several subadult and earlier instar Titiotus, presumably T. gertschi, new species, the only species known from that cave, were observed in a small room (.5 m diameter).”
This suggests a reason Titiotus is so common in homes, especially in cooler and darker areas, like basements… they love caves!
Acknowledgements: I would like to thank Rick Vetter for his review and comments about this page.
Click on an image to enlarge it. See also this page for more pictures.
male of the species: