REVISION OF THE MILLIPEDE GENUS XYSTOCHEIR COOK (POLYDESMIDA, XYSTODESMIDAE)

The California milliped genus Xystocheir Cook, occurring along the Pac ific Coast and the western slope of the Sierra Nevada, comprises nine species, three being divided into a total of seven subspecies; the spe cies are combined into four species-groups named for the oldest compon ent. Xystocheir dissecta (Wood), abundant around San Francisco - San P ablo and Monterey bays, comprises intergrades, one true subspecies, an d two apparent semispecies that are treated as subspecies; additionall y, a local population in southern Mendocino County has achieved reprod uctive isolation and attained species status. Two new combinations, X. reducta (Causey) and X. modestior (Chamberlin), are proposed, along w ith 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 D elocheir conservata and D. dalea, both by Chamberlin, under X, dissect a taibona Chamberlin, new status. The following new species-group taxa are diagnosed: the subspecies Xystocheir dissecta microrama, Xystoche ir modestior haerens, and Xystocheir stolonifera uncinata, and the spe cies X. prolixorama, X. solenofurcata, X. brachymacris, X. stenomacris , X. bistipita, and X. stolonifera.