Recent California collection records for three adventive species of soil-dwelling darkling beetles (Coleoptera: Tenebrionidae) are provided, with observational notes on habitats and spread. Gonocephalum sericeum (Baudi), a widespread, synanthropic species in northern Africa and Middle East, is reported from the Western Hemisphere for the first time. The species is illustrated and diagnosed, and the genus is incorporated into a key to North American Opatrini. Gondwanocrypticus platensis (Fairmaire), a South American species of Crypticini often associated with nest debris of imported fire ants, has spread widely in southern California. Opatroides punctulatus Brullé, first discovered in the Sacramento area in 2003–2008, has recently been found in abundance in and around Reno, Nevada and is spreading to new California counties. All three species are thought to be facultative opportunistic ant associates in disturbed habitats.