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This looks to be in the family Tengellidae, possibly in the genus Titiotus. I have heard of occurrences of this genus in Marin, Sonoma, and Contra Costa Counties. Wait for someone to confirm.
It definitely appears to be in the family Tengellidae, see http://tinyurl.com/cjcxds and scroll down to near the bottom. I'm not certain as to the genus; four genera have been reported from California - see http://tinyurl.com/m236mv