Two new species of the Heterobasidion insulare complex based on morphology and molecular data

•Two new species matching the concept of Heterobasidion were described.•Phylogenetic analysis was carried out based on RPB1 and RPB2 sequences.•Six species of the H. insulare complex were well supported as monophyletic group.

Two new species of Heterobasidion, H. amyloideum and H. tibeticum, are described and illustrated from eastern Himalayas. Both species are closely related to the Heterobasidion insulare complex in morphology, but they differ in presence of cystidia and amyloid skeletal hyphae in the context. Phylogenetically, the combined RPB1 and RPB2 sequence data supports H. amyloideum and H. tibeticum as two distinct species within the H. insulare complex.