Differential Parasitism by Sex on Plethodontid Salamanders and Histological Evidence for Structural Damage to the Nasolabial Groove

In the Ouachita Mountains of Oklahoma and Arkansas, the trombiculid mite, Hannemania dunni, infests five endemic salamander species (Plethodon ouachitae, P. caddoensis, P. fourchensis, P. kiamichi and Desmognathus brimleyorum). Plethodon albagula, which is widely distributed throughout much of Arkansas and southern Missouri, is rarely infested. In a field survey of 322 salamanders, 80.2% of P. ouachitae, 26.3% of P. caddoensis and 0% of P. albagula were infested with chiggers (larval mites). Males of P. ouachitae and P. caddoensis had significantly more chiggers than females, and site of infestation differed significantly between species. Histological examination of the nasolabial groove (a chemosensory structure) indicates that chigger attachment in the snout area can occlude the groove. Loss of chemosensory function in plethodontids has been shown to impair foraging ability and may adversely affect a salamander's ability to find mates and/or defend a territory. Host tissue response and positioning of the chigger in the dermis was similar to that reported in other amphibian hosts.