Apotritia walkeri, a new genus and species of oribatid mite in the family Synichotritiidae, is based on adult specimens from leaf litter in California. The family Synichotritiidae is redefined, with emphasis on the unique structure of the sagittally attached genital plates, the anteriorly directed ovipositor, and associated modifications. Two subfamilies are recognized: Synichotritiinae, including Sabahtritia and Synichotritia; and Temburongiinae, including Temburongia and Apotritia. A relictual distribution is suggested by the representation of each subfamily in North America and Borneo, and Synichotritia is first reported from the eastern United States (Florida).