Identification of astigmatid mites using the second internal transcribed spacer (ITS2) region and its application for phylogenetic study.

The second internal transcribed spacer (ITS2) of nuclear ribosomal DNA from 73 specimens of Astigmata was analyzed by PCR amplification and DNA sequencing. The length of the ITS2 region varied from 282 to 592 bp. The interspecific variation based on consensus sequences was more than 4.1%, while the intraspecific or intra-individual variation was from 0 to 5.7%. The variation between geographically separated populations (0-3.2%) was almost the same as the variation within strains. The sequences of the ITS2 region of Astigmata were concluded to be species-specific. The phylogenetic tree inferred from the ITS2 region supported Zachvatkin's morphological classification in the subfamily Rhizoglyphinae. The species-specific ITS2 sequence is useful for the species identification of astigmatid mites and for studying low-level phylogenetic relationships.