Hammeriella gen. n. and, Hammeriellidae fam. n. (Acari, Oribatei) from South America are described. Hammeriella is also recorded from "Tierra del Fuego" (Chile) and from Argentina. The type species of Hammeriella, Pedrocortesia grandis Hammer, is fully redescribed and the cogeneric species, Pedrocortesia australis Hammer, is diagnosed in comparison with the type species, both being transferred to Hammeriella. The redescriptions were made from syntypes deposited in the Zoologisk Museum of Copenhagen, sent on loan for this study.