Gracilidris is a genus of dolichoderine ants known from a single extant South American species, G. pombero, and a single extinct species from the Dominican Amber, G. humilioides. The recent discovery of living populations spurred the description of Gracilidris as a new genus (Wild & Cuezzo 2006), and has led to the observation that Gracilidris is a "Lazarus taxon", a group of organisms previously thought extinct that has appeared again after many millions of years. This is a bit of an exageration, however. The perceived rarity of living Gracilidris more likely stems from its nocturnal habits and its association with habitats that are not frequently visited by entomologists.
These slender ants can be distinguished from other dolichoderine ants by the large eyes that touch the lateral margins of the head in full-face view, the long antennal scapes, the lack of erect setae on the dorsum of the mesosoma, and (in G. pombero) the shape of the petiolar scale, which curves backward at the apex.
- Wild, A. L., and F. Cuezzo. 2006. Rediscovery of a fossil dolichoderine ant lineage (Hymenoptera: Formicidae: Dolichoderinae) and a description of a new genus from South America. Zootaxa 1142: 57-68.