This survey raises the number of registers referred to the State of Roraima to 28 species of Myxomycetes. Of these, 24 were collected in the Maracá Ecological Reserve (Lat.3°l 5' - 3°35'N, Long. 61°22' - 61°58'WG). The following families and genera are registered: Ceratiomyxaceae (Ceratiomyxa, 4 sp); Cribrariaceae (Cribraría, lsp, Dictydium, lsp); Didymiaceae (Didymium, 2 sp); Enteridiaceae (Lycogala, 1 sp, Tubifera, 2 sp); Physaraceae (Craterium, 2 sp, Fuligo, 1 sp, Physarum, 2 sp); Stemonitaceae (Comatricha, 1 sp, Stemonitis, 4 sp); Trichiaceae (Arcyria, 3 sp, Hemitrichia, 2 sp, Perichaena, 1 sp, Trichia, Isp). One family, seven genera and eleven species are new records for the State; one of them, Ceratiomyxa sphaerosperma Boedj., is new for Roraima State and Northern Brazil. Comments and geographical distribution of these species are presented.
Myxomycetes; floristics; ecological reserves; chorology; Ceratiomyxa