A revised checklist of Pottiaceae (Bryophyta) in Mongolia

This updated checklist of Mongolian Pottiaceae is based on a thorough review of over 2,000 specimens from HIMC, UBA, and MO, along with published records. A total of 1,030 occurrence records were verified at the sum level, where "sum" refers to an administrative unit, identifying 99 taxa, including 93 species and six varieties in 26 genera. Didymodon is the most species-rich genus, with 27 species and two varieties. The update adds one genus and 20 taxa (16 species and four varieties) to the Mongolian flora, while excluding nine previously reported taxa. Three names remain doubtful pending voucher confirmation. For each accepted taxon, evidence and distribution details are provided at the province/city and sum levels, together with an identification key to the genera of Mongolian Pottiaceae. The geographic summaries also reveal strong documentation unevenness among provinces, with observed richness closely tracking collecting intensity. The checklist is therefore intended as a voucher-based national baseline and a guide for future gap-filling surveys.