Revision of the milliped genus Xystocheir Cook (Polydesmida: Xystodesmidae)

The California milliped genus Xystocheir Cook, occurring along the Pacific Coast and the western slope of the Sierra Nevada, comprises nine species, three being divided into a total of seven subspecies; the species are combined into four species-groups named for the oldest component. Xystocheir dissecta (Wood), abundant around San Francisco – San Pablo and Monterey bays, comprises intergrades, one true subspecies, and two apparent semispecies that are treated as subspecies; additionally, a local population in southern Mendocino County has achieved reproductive isolation and attained species status. Two new combinations, X. reducta (Causey) and X. modestior (Chamberlin), are proposed, along with the following new synonymies: Paimokia Chamberlin under Xystocheir, X. acuta Cook, X. francisca and X. milpitas, both by Chamberlin, and Cheirauxus sapiens Chamberlin under X. d. dissecta, new status; and Delocheir conservata and D. dalea, both by Chamberlin, under X. dissecta taibona Chamberlin, new status. The following new species-group taxa are diagnosed: the subspecies Xystocheir dissecta microrama, Xystocheir modestior haerens, and Xystocheir stolonifera uncinata, and the species X. prolixorama, X. solenofurcata, X. brachymacris, X. stenomacris, X. bistipita, and X. stolonifera.