Definition de Phityogamasus n. g. et redescription de son espece type, Parasitus primitivus oudemans (Gamasides, Parasitidae). - Owing to a better knowledge of its systematic structure, the composite genus Pergamastts (sensu BERLESE, 1906) can be divided into several natural genera. The eight genera, which are recognized at present, are listed. The 8th one, Phityogamasus n. g., the type species of which is Parasitus primitivus Oudemans, 1904, is defined and a redescription of Phityogamastts P1 i1nitivtts (OuDEMANs) n. comb. is provided. The collections of this species exhibit a gondwanian distribution and were mostly obtained from tropical or subtropical wet forest litter.