Species diversity of bdelloid rotifer (Rotifera, Bdelloidea) in different areas in China, with a description of two new species.

China is one of the most biodiverse countries worldwide, with a variety of landforms and climatic conditions. However, the diversity and biogeographic distribution of bdelloid rotifers, one of the most widespread microscopic organisms worldwide, have received little attention in China. In order to understand the species diversity of bdelloid rotifers in China, a large-scale survey of different areas (such as karst areas, islands, and plateaus) and microhabitats (such as moss, leaf litter, and soil) was conducted using 299 samples from seven provinces from 2018 to 2022. A total of 109 bdelloid rotifer species were identified, including three newly recorded genera, 26 newly recorded species, and two new species (Adinetajinan Wang & Yang, sp. nov. and Philodinachinensis Wang & Örstan, sp. nov.), increasing the species richness of bdelloid rotifers in China to 141. Morphological variations among P.chinensis populations from three different regions were identified. This study indicated that the species diversity of bdelloid rotifers in China is high, especially in the Oriental region, and both endemic and rare species exist in different regions and habitats. Further, the challenges are highlighted with corresponding suggestions for research on the diversity and biogeographic distribution of bdelloid rotifers in China. Notably, our findings indicated that a survey of bdelloid rotifers in China is indispensable for a comprehensive understanding of their global biodiversity and biogeography.