Geographic distribution of, and genetic variation in, the wood roach Cryptocercus (Dictyoptera : Cryptocercidae) in the United States

Members of the genus Cryptocercus are subsocial, xylophagous cockroaches th at inhabit temperate forests of the Nearctic and Palaearctic. Seven species are recognized worldwide: five in the United States, and one each in Russi a and China. Four (Cryptocercus darwini Burnside, Smith and Kambhampati. Cr yptocercus garciai Burnside, Smith and Kambhampati, Cryptocercus punctulatu s Scudder. Cryptocercus wrighti Burnside, Smith and Kambhampati) of the fiv e species in the United States occur in the Appalachian Mountains and one ( Cryptocercus clevelandi Byers) occurs in the Pacific Northwest. Previous St udies have indicated that the distribution of the Appalachian species is al lopatric however, three of the four species occurred within a few kilometer s of one another. Therefore, an intensive survey was undertaken in southwes tern North Carolina and northern Georgia to determine if the species distri butions are indeed allopatric or if there are zones of sympathy. With regar d to C. clevelandi. previous studies have included samples from only a hand ful of locations in the western United States. Therefore, an extensive surv ey was undertaken in Oregon and California to map the geographic distributi on of C. clevelandi and estimate genetic variation within and among populat ions. Our surveys indicated that three (C. darwini, C. garciai, C wrighti) of the four Appalachian species have overlapping distributions in southwest ern North Carolina and Northern Georgia. a finding that raises the possibil ity of the existence of hybrid zones. Genetic variation among samples colle cted in Oregon and California indicated that, unlike the eastern United Sta tes. there is only one species of Cryptocercus in the western United States . In addition, we found that the distribution of C. clevelandi is considera bly more patchy than that of the Appalachian species.