The systematic position of endemic Early Miocene pectinid taxa of Patagonia contained in the uppermost horizons of the San Julián and Monte León formations and in the basal and middle beds of the Chenque Formation is revised. Two new genera are proposed: Reticulochlamys new genus with R. proximus (Ihering) as its type species and Jorgechlamys new genus with J. juliana (Ihering) as its type species. Two new species are described: Reticulochlamys zinsmeisteri new species from the Monte León Formation and Reticulochlamys borjasensis new species from the Chenque Formation.