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.