A new species of Limaytilla from Argentina is described and illustrated based on males, L. diaguita Torréns Fidalgo sp. nov.. Diagnoses for both sexes of the genus and an illustrated key for the Argentinian species are provided as well as new record data for L. pampa Casal and L. pehuenche Casal. Habitus photographs of all Argentinian species and L. orlandoi Cambra, Quintero Pagliano from Chile, are also provided.
Keywords: Hymenoptera, Sphaeropthalminae, Sphaeropthalmini, nocturnal wasps.