BackgroundThe Lowland tapir (Tapirus terrestris) is the largest Brazilian mammal and despite being distributed in various Brazilian biomes, it is seriously endangered in the Atlantic Rainforest. These hosts were never evaluated for the presence of Trypanosoma parasites.MethodsThe Lowland tapirs were captured in the Brazilian southeastern Atlantic Rainforest, Espírito Santo state. Trypanosomes were isolated by hemoculture, and the molecular phylogeny based on small subunit rDNA (SSU rDNA) and glycosomal-3-phosphate dehydrogenase (gGAPDH) gene sequences and the ultrastructural features seen via light microscopy and scanning and transmission electron microscopy are described.ResultsPhylogenetic trees using combined SSU rDNA and gGAPDH data sets clustered the trypanosomes of Lowland tapirs, which were highly divergent from other trypanosome species. The phylogenetic position and morphological discontinuities, mainly in epimastigote culture forms, made it possible to classify the trypanosomes from Lowland tapirs as a separate species.ConclusionsThe isolated trypanosomes from Tapirus terrestris are a new species, Trypanosoma terrestris sp. n., and were positioned in a new Trypanosoma clade, named T. terrestris clade.Electronic supplementary materialThe online version of this article (doi:10.1186/1756-3305-6-349) contains supplementary material, which is available to authorized users.