Nigrellomyces W. M. Zhang & Q. Y. Feng 2025, gen. nov.

Nigrellomyces W. M. Zhang & Q. Y. Feng gen. nov. Etymology. “ Nigrellomyces ” refers to the small, dark-colored conidia characteristic of this genus. Description. Saprobic on decaying wood submerged in a freshwater stream. Asexual morph: Colonies superficial, effuse, hairy, brown to black, scattered, with glistening conidial masses at apex. Mycelium partly superficial, partly immersed, consisting of branched, septate, smooth, smooth-walled, hyaline to pale brown hyphae. Conidiophores macronematous, mononematous, solitary, erect, unbranched, septate, straight or flexuous, cylindrical, slightly constricted at septa, dark brown, becoming pale brown to brown towards the apex. Conidiogenous cells polyblastic, integrated, terminal or intercalary sympodial proliferations, sometimes denticles, cylindrical, reniform, swollen at the top, pale brown to brown. Conidia acrogenous, subglobose to globose, ovoid to obovoid, or ellipsoidal, aseptate, occasionally forming chains in water, guttulate, subhyaline to brown or black, smooth-walled. Sexual morph: Undetermined. Type species. Nigrellomyces aquaticus W. M. Zhang & Q. Y. Feng Notes. Morphologically, Nigrellomyces can be readily distinguished from other genera in Pleurotheciaceae by its polyblastic, reniform conidiogenous cells with curved apices and subglobose to globose, ovoid to obovoid, or ellipsoidal, aseptate conidia that occasionally form chains in water. Phylogenetically, Nigrellomyces forms a distinct clade within Pleurotheciaceae, supporting its recognition as a new genus. Herein, we establish the genus Nigrellomyces to accommodate a new species, N. aquaticus, which is designated as the type species based on both molecular evidence and its distinctive conidial morphology.