THE CHONAPHINI, A BIOGEOGRAPHICALLY SIGNIFICANT MILLIPEDE TRIBE IN EASTERN AND WESTERN NORTH-AMERICA (POLYDESMIDA, XYSTODESMIDAE)

The Chonaphini, the only Nearctic xystodesmid tribe represented in bot h the eastern and western faunal regions, is the only tribe in the fam ily in which the prefemoral process is typically more complex and of g reater taxonomic utility than the acropodite. The latter structure var ies from narrowly blade-like to acicular, and excepting Montaphe parap hoena, n.sp., lacks secondary projections. The prefemoral process, how ever, is often elaborate with secondary structures arising from the st em. Six genera, three monotypic, and twelve species comprise the tribe , with Semionellus Chamberlin and S. placidus (Wood) inhabiting four a reas in the eastern United States from southeastern Minnesota to westc entral Virginia. The other taxa occur west of the Continental Divide f rom Montana to northcentral California and Vancouver Island, Canada. C honaphe Cook is represented by two new and two established species in the United States, C. evexa and schizoterminalis, and C. remissa Chamb erlin and armata (Harger). Chonaphe cygneia and patriotica, both autho red by Chamberlin, and C. serratus Loomis and Schmitt are placed in sy nonymy under C. armata. Montaphe elrodi (Chamberlin), the dominant xys todesmid from eastern Washington to western Montana, is projected to o ccur in the southern extremity of central British Columbia adjacent to Idaho and northeastern Washington. Metaxycheir Buckett and Gardner an d Tubaphe Causey are monotypic, M. prolata Buckett and Gardner occurri ng in eastern Washington and the adjoining part of northern Idaho, and the subcylindrical T. levii Causey occurring in wet rainforests of th e Olympic Mountains and the southwestern corner of Vancouver Island. S elenocheir n. gen., characterized by a short prefemoral process less t han half as long as the acropodite, consists of three new species rang ing from southwestern Oregon to the northern California coast and the northern Sierra Nevada Mountains. Modern descriptions and illustration s are presented for all tribal taxa along with keys to genera and to t he species of Chonaphe and Selenocheir.