On Gyropus parvus parvus (Ewing, 1924) and Phtheiropoios rionegrensis sp. n. (Phthiraptera, Amblycera, Gyropidae), parasitic on Ctenomys haigi Thomas, 1919 (Mammalia, Rodentia, Ctenomyidae). Iheringia Serie Zoologia, 77, 30 set 1994: 3-14. 4 [Zoological Record Volume 131]