Genetic structure in populations and species of Steganacarus soil mites (Acarida, Oribatida, Phthiracaroidea)

Populations of five species of the genus Steganacarus (Acarida, Oribatida, Phthiracaroidea) from Italy were surveyed for genetic variation. Morphologically, the samples included two populations of Steganacarus (Tropacarus) carinatus, two of S. (Tropacarus) brevipilus, one of S. (Rhacaplacarus) ortizi, one of S. (Steganacarus) hirsutus and eight of S. (Steganacarus) magnus all electrophoretically analyzed in previous studies. All populations were compared using Wright's Fst and Nm indices, and Nei's genetic distances. Systematic relationships were studied by UPGMA clustering of genetic distances and principal component analysis of allele frequencies. Results from this comparison confirm the clear genetic and systematic affinity of S. (T.) brevipilus with S. (T.) carinatus. The low level of heterozygosity in the species studied is discussed.