Integrated Bayesian species delimitation and morphological diagnostics of chorioptic mange mites (Acariformes: Psoroptidae: Chorioptes)

The external morphology of adult and immature stages of mange mites of the genus Chorioptes was investigated with the aid of light and scanning electron microscopy. A molecular phylogeny of this genus was inferred based on six genes (18S, 28S rDNA, EF1-α, SRP54, HSP70, and CO1). The validity of four species (Ch. bovis, Ch. panda, Ch. texanus, and Ch. sweatmani sp. nov. described from the moose from Sweden, Finland, and Russia) was confirmed based on morphology and a Bayesian species delimitation analysis incorporating both gene tree uncertainties and incomplete lineage sorting via the coalescent process model in BPP. Sequence data for Ch. crewei and Ch. mydaus was not available but their morphology strongly suggests their validity. The six valid Chorioptes species are diagnosed using type and non-type specimens, and a key to species is provided. Ch. sweatmani differs from closely related Ch. texanus by the following features: in males, the body length, including the gnathosoma, is 380–405 μm (vs. 220–295 in Ch. texanus), the idiosoma is 3–4 times longer than setae cp (vs. 1.3-1.6 times longer), legs III are approximately three times longer than setae sRIII (vs. 1.8–2 times longer), the apical spur of tarsus III is curved (vs. straight), a spur near seta fIII base is not developed (vs. small but distinct); in females, setae h2 are 1.4–1.5 times shorter than legs IV (vs. about two times longer). Hosts and distribution records of Chorioptes species are summarized.