Phaeolus flavobrunneus sp. nov., a new brown-rot fungus associated with declining Himalayan conifers

To assess the health status of deteriorated Himalayan coniferous trees, identification, and characterization of the associated pathogenic Phaeolus species using morphological, anatomical, and molecular characteristics. A series of subsequent terrain observations were carried out in both protected areas mainly in dead or in poor health status stands. The observations of Pinus wallichiana A.B. Jackson, P. excelsa Wall. ex D. Don, and P. longifolia Roxb. ex Lamb. stands revealed the occurrence of Phaeolus species, particularly on dead and declining trees. A new species, Phaeolus flavobrunneus sp. nov., was identified for the first time from Khanspur Helipad, Pakistan. The species was characterized by stipitate, non-laccate, very soft basidiomata with a dark chocolate-brown pileal surface and a broad mustard-yellow crust extending toward the margins. Basidiospores were light brown, guttulate, and ellipsoid to oblong-oval, measuring 5.4–7.8 × 3.6–4.3 μm. Morphological and anatomical characteristics, together with ITS-based phylogenetic analysis, supported its distinction from related taxa. The phylogenetic analysis placed P. flavobrunneus as a distinct lineage closely related to P. schweinitzii (Fr.) Pat., with 100% bootstrap support.