Chorioptes mites: re‐evaluation of species integrity

Chorioptes mites (Acari: Psoroptidae) are non‐burrowing agents of mange which parasitize a wide range of domesticated and wild ungulates. Considerable historical confusion has surrounded the description and naming of the various species of Chorioptes . Here, the opisthosomal setae of male adult Chorioptes mites from a range of host species and geographic locations were subjected to detailed analysis. Discriminant analysis suggests the existence of three clear morphotypes. The first, Chorioptes bovis , is characterized by a very long seta 1 (ae) and short spatulate setae 2 (l4 and d5), whereas, in the second, Chorioptes texanus , setae 2 (l4 and d5) are longer and narrower than in C. bovis , but most of the other setae are shorter; this is particularly true for seta 1 (ae). A third morphotype is characterized by a seta 1 (ae) that is shorter than in C. bovis but longer than in C. texanus , long setae 2 (l4 and d5) and a long seta 6 (l5). The data are compared with previously published measurements. Although this analysis supports the validity of C. bovis and C. texanus as morphologically distinct, it also supports the existence of a proposed third species of Chorioptes , as described by Hestvik et al. in 2007, and suggests that the mites described by Sweatman in his classic 1958 description of C. texanus , which were obtained from the ears of semi‐domesticated reindeer, are likely to have been specimens of this as yet unnamed species. The results show that there is a high degree of phenotypic plasticity in setal lengths. It is concluded that a statistical difference in the absolute measurement of any one seta is not a reliable species indicator; the relative sizes of groups of setae would appear to be more taxonomically informative and should be used when identifying Chorioptes morphologically.