Lyrifissella new genus and Lyrifissellidae new family (Acari, Oribatei) are described. The type species, Pedrocortesella latoclava Hammer, 1966, from Milford, New Zealand, is fully redescribed from the holotype. The congeneric species, Pedrocortesella cryptonota Hammer, 1966, Lake Ratoitis, New Zealand, is compared with the type species and transferred to the new genus. Plateremaeus vestitus Tragardh, 1931, the species thought to be very close to Plateremaeus ornatissimus (Berlese), and which was erroneously used to characterize Plateremaeus and Plateremaeidae, causing them to be misunderstood for about five decades, is now placed in Lyrifissella.