Date of Graduation


Document Type


Degree Name

Doctor of Philosophy in Biology (PhD)

Degree Level



Biological Sciences


Steven L. Stephenson

Committee Member

Frederick W. Spiegel

Second Committee Member

Mary C. Savin

Third Committee Member

Allen L. Szalanski


Amazon, Atlantic Rainforest, Dictyostelids, Microbial Diversity, Myxobacteria, Myxomycetes, Protosteloid Amoebae


Tropical rain forests cover less than two percent of Earth's surface, yet they sustain the greatest diversity of living organisms on the planet. Tropical rain forests cover nearly 73% of the Brazilian territory and besides harboring some of the most biodiverse ecosystems on the planet, this vast area also houses about 83% of the Brazilian population. Approximately 175 million people live in urban and rural areas with fragments of coverage of these biomes which contributes to the loss of biodiversity that rapidly increases over the years. Furthermore, the majority of the taxonomic and ecological efforts to describe and protect the Brazilian tropical biodiversity are usually focused on macroorganisms while the knowledge regarding the heterogeneity of microorganism species that compose the Brazilian microbiota increases slowly. Therefore, urgent efforts should be directed to the carrying out of inventories and studies on the species that make up the Brazilian microbiota, their biogeographical patterns, and their interactions with the environment in which they occupy. Aiming to contribute to the knowledge of the distribution and diversity of microorganism in the Neotropics, this dissertation includes (1) an overview of the biogeographical patterns of microorganisms; (2) a bibliographic revision of the myxomycetes species found in Brazil distributed among the different vegetation physiognomies throughout the country; (3) species listing and molecular identification of myxobacteria species; (4) the taxonomic and ecological studies of species of ceratiomyxomycetes and myxomycetes; (5) the taxonomic composition of dictyostelid cellular slime molds; and (6) species of protosteloid amoebae and related organisms present in tropical and subtropical moist broadleaf forests of Brazil.