A GUIDELINE FOR THE IDENTIFICATION OF SUBFOSSIL TANYTARSINI (DIPTERA: CHIRONOMIDAE: CHIRONOMINAE) FROM PATAGONIA. This paper presents a key for the identification of nine subfossil morphotypes of the Tribe Tanytarsini (Subfamily Chironominae), described for Argentinean and Chilean Patagonia, from 39° to 54°S. The key is structured based on the head capsules, which is the only material preserved in the sedimentary record. Tribe Tanytarsini is of particular importance as it includes species with high environmental importance, especially climatic. The material collected in Argentinean and Chilean Patagonia allowed the classification of nine morphotypes, distinguished mainly by four easily observables characteristics; (1) the spur shape of the antennal pedestal, (2) presence and shape of post-occipital plate, (3) number of premandible teeth, and (4) mentum and ventromental plates. The main goal of this contribution is to bring together the very sparse and limited knowledge on Tanytarsini from southern South America, in a simple and practical key helping the identification and separation of morphotypes, especially useful for scientists working with fossil chironomids from the Quaternary of Patagonia and other regions of the Southern Hemisphere.