In sampling fungi from the built environment, two isolates that could not confidently be placed in described species were encountered. Phenotypic analysis suggested that they belonged in Aspergillus sect. Usti. In order to verify the sectional placement and to assure that they were undescribed rather than phenotypically aberrant isolates, DNA was isolated and sequenced at the beta-tubulin, calmodulin, internal transcribed spacer, and RNA polymerase II loci and compared to those sequences from other species in Aspergillus. At each locus each new isolate was distant from existing species. Phylogenetic trees calculated from these data and GenBank data for section Usti species excluded the placement of these isolates in existing species, with statistical support. Because they were excluded from existing taxa Aspergillus asper (type strain NRRL 35910T=CBS140842T) and Aspergillus collinsii (type strain NRRL 66196T=CBS140843T) they were described as distinct species in sect. Usti.