Application of ITS-2 sequences as markers for identification and phylogenetic inference within the genus Geomylichus (Acari: Listrophoridae).

Phylogenetic relationships among 18 samples from nine nominal species of Geomylichus (Acari: Listrophoridae), were analyzed based on internal transcribed spacer 2 (ITS 2) sequences, Prolistrophorus sp. was used as an outgroup. Maximum likelihood and neighbor-joining analyses indicated that Geomylichus is formed by at least three internal clades. Genetic distance among Prolistrophorus and Geomylichus was 27.8-35.5%, and among species, populations, and infrapopulations of Geomylichus it was 0.4-21.8%, 0.8-2.4%, and 0.8-1.2%, respectively. Differences between the results of this analysis with conventional taxonomy of the group, as well as the overlapping of genetic distances among species, populations, and infrapopulations, suggest that the definition of species within Geomylichus deserves reconsideration. For example, the recognition of inconsistencies among G. texanus populations associated to different host species, resulting from the molecular analysis, led us to collect new morphological evidence now suggesting that this taxon represents more than one species.