A solution to the enigma of the type locality of Telmatobius halli Noble, 1938 (Anura, Telmatobiidae), a frog lost for 86 years Claudio Correa 1 1 Laboratorio de Sistemática y Conservación de Herpetozoos, Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográfcas, Universidad de Concepción, Barrio Universitario S/N, Concepción, Chile Corresponding author: Claudio Correa (ccorreaq@udec.cl) Academic editor: Angelica Crottini  |  Received 26 April 2021  |  Accepted 29 July 2021  |  Published 24 September 2021 http://zoobank.org/95CE80C0-C741-421E-B105-DE67A7D0CB43 Citation: Correa C (2021) A solution to the enigma of the type locality of Telmatobius halli Noble, 1938 (Anura, Telmatobiidae), a frog lost for 86 years. ZooKeys 1060: 183–192. https://doi.org/10.3897/zookeys.1060.67904 Abstract For 80 years, there were no sightings of the Andean frog, Telmatobius halli, due to the ambiguity with which its type locality was described (“warm spring near Ollagüe”, northern Chile). Te type specimens were collected during the International High Altitude Expedition to Chile (IHAEC) in 1935 and were subsequently described in 1938. In 2018 and 2020, two studies independently reported the rediscovery of the species, but they reached diferent conclusions about its identity and geographic distribution. In fact, the populations identifed as T. halli in those studies are more phylogenetically related to other spe- cies than to each other, so they clearly do not belong to the same taxon. Although the study of 2020 is more in line with the geographic information of the description, it does not consider some bibliographic details and the transport limitations of the IHAEC. Here, based on a detailed analysis of the chronicles of the IHAEC and other bibliographic sources, I frst refute the proposals of the 2018 and 2020 studies and then provide a possible solution. Te combined information from the chronicles indicates that the type locality of T. halli is found at the sources of the Loa River, a diferent place from those identifed in the two previous studies. By also incorporating geographic information of the time, I conclude that its true type locality is Miño, an abandoned mining camp located near the origin of the Loa River, where currently no populations of the genus have been described. Keywords Hall’s water frog, International High Altitude Expedition to Chile, Loa River, Miño, northern Chile, Ollagüe ZooKeys 1060: 183–192 (2021) doi: 10.3897/zookeys.1060.67904 https://zookeys.pensoft.net Copyright Claudio Correa. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. COMMENTARY Launched to accelerate biodiversity research A peer-reviewed open-access journal