Morpho-phylogenetic evidence reveals a new species and two known taxa of Neomyrmecridium from freshwater habitats in the Nujiang River, Yunnan, China

The Nujiang River, an important international river and one of the six major water systems in Yunnan Province, China, is characterized by numerous tributaries, complex topography, and abundant natural resources. During an investigation of lignicolous freshwater fungi in this river, three Neomyrmecridium taxa were isolated from submerged wood samples. Based on morphological characteristics and phylogenetic analyses of combined ITS and LSU sequence data, we introduce a novel species, Neomyrmecridium nujiangense. Additionally, two known species were identified as N. aquaticum and N. fusiforme. This study provides detailed morphological illustrations and phylogenetic trees of both the new and known taxa. Our findings enhance the understanding of freshwater fungal diversity in the Nujiang River and highlight the essential role of integrating morphological and molecular data in fungal taxonomy, particularly for groups exhibiting high phenotypic plasticity.