Phylogeny of Cryptocercus species (Blattodea : Cryptocercidae) inferred from nuclear ribosomal DNA

The wood-feeding cockroaches of the genus Cryptocercus occur in temperate f orests. Of the seven known species, five occur in the United States and two in Eurasia. Until 1997, all populations in the United States were consider ed a single species. Populations in the western United States were elevated to a species status based on variation in DNA sequence and morphology. In 1999, three new species were described from the eastern United States based on variation in chromosome number and mitochondrial DNA, bringing the numb er of species in the United States to five. The objective of this study was to determine if the DNA sequence of nuclear rRNA also signals the existenc e of four species in the eastern United States and to compare the inferred relationships with those proposed based on mitochondrial sequences. We obta ined the DNA sequence from a portion of the 5.8S and 28S rRNA genes and the entire ITS2 region from 38 individuals and 30 additional clones to assess intraindividual, intraspecific, and interspecific variation. We found exten sive sequence variation among the various species and little or no intraind ividual and intraspecific variation. Phylogenetic analysis indicated the ex istence of monophyletic lineages among the eastern United States samples, w hich largely corresponded to the four species previously described. The inf erred relationships were well-supported by bootstrap analysis and decay ind ices. Although the nuclear rRNA sequences resulted in a coherent phylogenet ic tree, the ITS2 region contained many insertions and deletions, which may introduce homoplasy and ambiguity in alignment as more taxa are added to t he data set. (C) 2001 Academic Press.