Argentinatachoides balli, new genus, new species, in the tribe Bembidiini is described and illustrated, and its microhabitat noted. Adults of this new species were found in Argentina, east of the Andean Cordillera, in Mendoza and La Rioja Provinces. The subulate apical palpomeres and other characters place this new genus in Bembidiini and the sub-oblique notched anterior tibiae assign it to the subtribe Tachyina. Structural attributes, for example the elytral recurrent groove appearing double and the symmetrical basal lobes of the aedeagal median lobe, indicate that this species is related to the Australian-Tasmanian genus, Tasmanitachoides Erwin, 1972. This discovery amplifies the known range of a particular fauna of Carabidae that was once widely distributed in the western part of Gondwana. Some aspects of the biogeography of the group are discussed.