摘要：Little information can be found on the geographical distribution of the genus Pythiogeton in the world, particularly in South America. In research studies, the technique of multiple baiting has been used for the isolation of these organisms in order to identify the geographical distribution of the genus. One species, Pythiogeton utriforme Minden, has been reported for Argentina, occurring in Buenos Aires (Chascomús), and four for Brazil: P. dichotomum Tokunaga, in Piauí (Parque Nacional de Sete Cidades); P. ramosum Minden, in Rio de Janeiro (Parque Nacional de Itatiaia), Pernambuco (Reserva Florestal Dois Irmãos), São Paulo (Represa de Guarapiranga), Amazonas (Manaus) and Piauí (Parque Nacional de Sete Cidades); P. uniforme Lund, in Piauí (Parque Nacional de Sete Cidades); and P. utriforme Minden, in Piauí (Parque Nacional de Sete Cidades). Herein, thirteen new occurrences of these species are reported for six new localities (five in the state of Piauí and one in Maranhão), increasing the knowledge of the geographical distribution of Pythiogeton in the country. The occurrence of P. utriforme with a clearly aplerotic oospore as well as a plerotic oospore, a feature exclusive to Pythiogetonaceae M.W. Dick, is discussed. Internal proliferation of the oogonium, with the formation of a new oogonium with antheridia and oospore was also observed. Descriptions, with special emphasis on morphology, and a brief discussion on the taxonomy and distribution, including drawings and photographs, are presented
