Plants of the genus Nothofagus (Fagales, Nothofagaceae) has ancient South American-Australasian disjunctive distribution and represent a perspective model for biogeographical studies in Eriophyoidea. Among six currently known eriophyoid genera reported from Nothofagus (Acalitus, Aceria, Austracus, Cymoptus, Rectalox, and Nothacus) only genus Cymoptus was registered in western and eastern distribution areas of Nothofagus. In this paper we describe a new vagrant species, Solenocristus nothofagalisn. sp. (Phytoptidae, Sierraphytoptinae) collected from lower leaf surface of Nothofagus pumilio in Los Glaciares National Park (Patagonia, Argentina). Because all mite specimens in the sample were dead, amplification of three marker genes (COI, 18S, 28S) performed ten days after collecting data was unsuccessful. Morphological identification of the host plant was confirmed using PCR method and resulted in new sequences of 18S (MT164471) and ITS1–5.8S–ITS2 region (MT164174) of N. pumilio, deposited in GenBank.