Clonostachysallendensis sp. nov.: A New Species Isolated from Bean Straw in Durango, Mexico

The genus Clonostachys comprises morphologically similar species whose delimitation often requires integrative taxonomic approaches. In this study, three fungal strains (RC2, RC5, and RC7) isolated from pinto bean (Phaseolus vulgaris L.) straw collected in the Los Llanos region of Durango, Mexico, were examined using morphological and multilocus phylogenetic analyses. Phylogenetic reconstruction based on five loci (ITS, LSU, TEF1, TUB2, and RPB2) consistently resolved the isolates as a single, strongly supported monophyletic lineage distinct from closely related species, including Clonostachys rhizophaga, C. chloroleuca, and C. kunmingensis. Morphologically, Clonostachys allendensis is distinguished from its closest phylogenetic relatives by a combination of yellowish perithecia, cylindrical to slightly ampulliform phialides, predominantly unicellular ellipsoidal conidia, and pale pink to salmon colony pigmentation. In addition, multilocus phylogenetic analyses consistently recovered C. allendensis as a distinct and well-supported lineage within Clonostachys. Among the isolates examined, strain RC7 (CM-CNRGᵀ) was designated as the type strain. Based on the combined molecular and morphological evidence, this lineage is herein described as Clonostachys allendensis sp. nov. This study expands current knowledge of Clonostachys diversity in Mexico and contributes to the understanding of fungal diversity associated with agricultural residues.