Skin folds in the gekkonid lizard genus Rhacodactylus: a natural test of the damage limitation hypothesis of mite pocket function

Abstract

The hypothesis that lizard mite pockets have evolved as a host response to limit damage by ectoparasites is tested. Evidence from the New Caledonian geckos of the genus Rhacodactylus does not support the hypothesis. Putative pockets in popliteal position are present in all taxa examined, but are infested by trombiculid chiggers only in Rhacodactylus auriculatus, a partially terrestrial species. Tissue damage results from the formation of a stylostome within the host pocket. No mechanisms for host amelioration of parasite effect are evident. At least in Rhacodactylus, chiggers appear to facultatively exploit skin folds or pockets, which may have evolved and been maintained as a result of selective forces unrelated to ectoparasite damage limitation.