Deep-soil arthropods remain one of the least studied components of terrestrial biodiversity, and we present, as an exciting discovery, a new endogean beetle collected by floating deep soil samples in Chile. We analysed a 4203-ortholog dataset using both maximum likelihood (ML) and coalescent methods to infer its relationships. Regardless of the analytical setup, this lineage was recovered as sister to the clade consisting of Lycidae, Cantharidae, Elateridae and the lampyroids. The distant position of this new taxon relative to previously described elateroid families is confirmed by additional analyses of differently sampled, although less phylogenetically informative, 66-gene and mitogenome datasets. As a result, we describe Badmaater chilensis sp. and gen. nov. in Badmaateridae fam. nov. (Coleoptera: Elateroidea). Badmaater resembles other clicking elateroids but has a three-segmented antennal club, slender palpi and globular metacoxae that are situated close to each other. It is blind, wingless and extremely small-bodied. We date the origin of Badmaateridae to the Triassic. The ancient origin of Badmaateridae suggests that this lineage has probably survived all disturbances shaping modern life, from the Triassic/Jurassic volcanic activity to the end-Cretaceous asteroid impact and subsequent Cenozoic and Quaternary climatic fluctuations. However, Badmaateridae is now one of the few beetle families with only a single species restricted to a narrow range. Deep-soil dwelling Badmaater survived in a relatively high-latitude area periodically affected by close glaciers and separated from the tropics by an arid zone. Badmaater, as a wingless deep-soil beetle occurring in a restricted area, has a limited dispersal propensity and consequently faces an inherent risk during turbulent environmental changes.