The adult female and the first-instar nymph of Acanthococcus piptadeniae (Hempel), from Brazil, are redescribed and illustrated, and two new species from Argentina are described and illustrated based on the adult female. A key to Acanthococcus species with six setae on the protibiae and five on meso- and metatibiae, including Acanthococcus dubius (Cockerell), cited in the Neotropical Region, is presented.
Argentina; Brazil; Eriococcus; taxonomic key
