Two new species of Annulatascaceae (Annulatascales, Sordariomycetes) from Dongting Lake

Freshwater fungi in Annulatascaceae represent a morphologically diverse but taxonomically challenging group, with several genera remaining poorly defined due to morphological convergence and a lack of molecular data. In this study, two novel species, Annulatascus dongtingensis sp. nov. and Fusoidigranularius dongtingensis sp. nov., are introduced from Dongting Lake in the mid-lower Yangtze River basin, China. Among them, F. dongtingensis broadens the known morphological variation of the genus by exhibiting a vertically oriented ostiolar neck.

Maximum likelihood and Bayesian analyses of ITS, LSU, and SSU sequences showed that both species represent distinct lineages. Annulatascus dongtingensis formed a sister clade to A. hongkongensis and A. thailandensis, whereas Fusoidigranularius dongtingensis grouped with its type species, F. nilensis.