An updated checklist of freshwater rotifers in Thailand: Taxonomy, diversity and distribution.

Background: The Rotifera is the most diverse group of freshwater zooplankton. In Thailand, the research on rotifers began in 1907. Following extensive studies on rotifers in Thai water bodies, the first checklist was published in 2013, with approximately 398 species. However, the taxonomy and diversity of bdelloid rotifers, a major group of freshwater rotifers, have only been intensively studied since 2016. Therefore, we provide an updated and comprehensive checklist of freshwater rotifers in Thailand, including nomenclatural updates, species diversity, and geographical distribution. New information: An updated checklist of rotifer fauna from inland aquatic habitats in Thailand-a high-diversity hotspot in Southeast Asia-is presented based on published records. This checklist includes revised nomenclature and updated species distributions. A total of 409 valid recorded species reflects relatively high diversity. However, estimators suggest that more species are likely to be discovered with further research. Planktonic monogononts are relatively well studied, whereas sessile monogononts and bdelloids require more attention. Additionally, large research gaps remain in the western and eastern regions. Each habitat type appears to support a distinct rotifer community, as indicated by generally low similarity values (Jaccard index < 0.53). Thus, habitats with unique characteristics, such as cave pools and limno-terrestrial habitats, warrant further investigation. Since the taxonomic status and species diversity have been consolidated, the geographical distribution is discussed.