Discovery of a novel endophytic species of Nigrograna (Nigrogranaceae) associated with Azadirachta indica (Neem) from the Deccan Plateau

Endophytic fungi inhabit internal plant tissues without causing disease, often forming complex and beneficial associations with their hosts. As part of a study on the endophytic fungal diversity of Azadirachta indica (neem) from the Deccan Plateau, India, two greyish white fungal isolates with moderate growth rate were obtained from the petiole and lamina of healthy neem leaves. Morphological traits and culture characteristics of both isolates suggested their affiliation with the genus Nigrograna (Pleosporales, Ascomycota). To resolve their taxonomic position, comprehensive morphological examinations were coupled with multilocus phylogenetic analyses using ITS, LSU, SSU, rpb2, and tef-1α gene regions. Both isolates clustered together in a distinct, well-supported clade, clearly separated from known Nigrograna taxa. Based on consistent morphological, cultural features and robust molecular evidence, we propose these isolates as representing a novel species, Nigrograna sunildeshmukhii sp. nov. This study constitutes the first report of a Nigrograna species associated with A. indica and contributes to the expanding diversity of endophytic fungi from the ecologically significant Deccan Plateau. The isolation of the same species from both petiole and lamina regions also suggests tissue versatility and ecological adaptation within the host.