The fungi of the order Uredinales known as "rust", are classified in the class Urediniomycetes, of the phylum Basidiomycota. It is a group with more than 6,000 known species and are characterized by being pleomorphic, ecologically obligate parasites, with high specificity in relation to their hosts and great dispersive capacity. The objective of this work was to identify the specimens of Uredinales collected at the research site of the Biodiversity Program (PPBIO) of the Eastern Amazon, located in the Caxiuanã National Forest, in the State of Pará (1° 42'30" to 2°15' 00" 5 and 51 ° 15' 00" to 510 56'00" W). A 25 km grid (5x5 km) is implanted in this site, with 30 plots of 250 m and a whole system of trails that gives access to the plots. The specimens studied were collected during two excursions carried out by the fungi protocol team of the project, from December 5 to 17, 2006 and August 14 to 27, 2007. The collections were made in nine plots in a 250 x 4 m strip, and randomly on the grid trails. All the plants that presented symptoms such as leaf spots, pustules and galls were collected, pressed, dried in a gas oven and in the laboratory were screened for identification of the rusts. The species identification stage was performed based on the hosts, macroscopic observations of the symptoms in a stereoscopic magnifying glass and observation of microstructures in an optical microscope, complemented with specialized bibliography and comparative studies with specimens deposited in the MG herbarium. For microscopic analysis, semi-permanent spore slides were prepared, mounted in lactoglycerol solution and heated. Of the nine plots sampled, at least one specimen of Uredinales was found in seven, totaling 17 samples and 11 taxa. The specimens collected on the trails are still in the screening and identification phase, so far four taxa have been identified. As partial results of the studies carried out, 15 taxa of the order Uredinales were identified, classified into two anamorph genera (Aecidium and Uredo) and six teleomorph genera, representing the families Chaconiaceae (Chaconia), Phakopsoraceae (Batistopsora and Cerotelium), Pucciniaceae (Puccinia), Raveneliaceae (Apra) and Uropyxidaceae (Porotenus). The identified rusts specimens were parasitizing 10 host plant genera, classified in seven plant families (Annonaceae, Bignoniaceae, Clusiaceae, Fabaceae, Heliconiaceae, Marantaceae and Rubiaceae), The species Uredo psychotrichica P. Hennings represents the first record for Amazonia. The species Puccínía psychotríae P. Hennings is a new occurrence for the State of Pará, adding the species Cerotelíum rectangulata Buriticá & Hennen and Puccínía fallax Arthur as new occurrences for the Caxiuanã Flona. After the identifications are completed, the spatial distribution of the Uredinales in the PPBIO grid and the tested sampling design will be analyzed.
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