Two cases of renal klossiellosis were diagnosed by histopathology in pet sugar gliders (Petaurus breviceps). In both cases, parasites were associated with tubular dilation and mild interstitial nephritis. Rare schizonts were seen in the proximal convoluted renal tubular epithelium, whereas all other life cycle stages were found within distal convoluted tubule cells or the urinary space of the structures distal to the loop of Henle. Conventional optical and transmission electron microscopies were used to assess the life stages of the parasite. The morphologic characteristics and measurements observed differ from those of previously described species of Klossiella infecting marsupial hosts, and the name Klossiella dulcis n. sp. is hereby proposed. This is the first report of a Klossiella sp. infection in Petaurus breviceps.