Three new fungal species, Septobasidium macrobasidium, S. puerense and S. wuliangshanense, are proposed based on a combination of the morphological features and molecular evidence. The taxon S. macrobasidium is characterized by the coriaceous basidiomata with a cream surface, cylindrical basidia, straight, 4-celled, subglobose or ovoid probasidia and thin-walled, narrowly cylindrical basidiospores with septa, measuring as 7–9 × 3.5–4.5 µm, the haustoria consisting of irregularly coiled hyphae; in addition, this fungus was found associated with the insect of Diaspididae. The species S. puerense is characterised by resupinate coriaceous basidiomata with a cinnamon brown to chestnut brown surface, cylindrical or slightly irregular basidia, 2-3-celled, slightly curved, subglobose to pyriform probasidia, probasidia cell persistent after the formation of the basidia and the haustoria with two types consisting of irregularly coiled hyphae and spindle-shape. The fungus was found associated with the insect species Pseudaulacaspis pentagona. The species S. wuliangshanense is characterised by the coriaceous basidiomata with a slightly brown surface, cylindrical or slightly irregular basidia, 2-3-celled, straight or slightly curved, pyriform, subglobose or ovoid and probasidia, haustoria consisting of irregularly coiled hyphae, associated with the insect genus Aulacaspis. Sequences of internal transcribed spacer region (ITS) were analysed maximum likelihood, maximum parsimony and Bayesian inference methods. The new species S. macrobasidium was clustered with S. maesae. Furthermore, S. puerense was retrieved as a sister to S. carestianum. The phylogenetic tree, inferred from the ITS sequences, highlighted that S. wuliangshanense was the sister to S. aquilariae with strong supports. Application of PHI test to the ITS tree-locus sequences revealed no recombination level within phylogenetically related species.
