关键词: 蛭态轮虫, 物种多样性, 分类学, 生物地理分布, 物种名录

Abstract

Aims: Bdelloid rotifers are characterized by obligate parthenogenesis, cryptobiosis, and horizontal gene transfer, making them an important group for investigating microscopic animal diversity and adaptive evolution. However, their species composition and geographical distribution in China remain insufficiently understood. Difficulties in identifying living specimens, substantial cryptic diversity, and limited research attention have constrained the accumulation of taxonomic and distributional knowledge. This study aimed to synthesize historical records and recent field survey data to characterize the species diversity and geographical distribution of Chinese bdelloid rotifers, summarize their occurrence across habitats, and assess how differences in survey coverage influence the interpretation of recorded diversity. 

Method: We integrated 52 valid literature records published since 1893 with survey data collected from 1,306 sampling sites across 25 provincial-level administrative regions in China between 2017 and 2026. These sources were used to summarize recorded species, including subspecies, and examine their distribution among provinces and habitats. Particular attention was given to records from leaf litter, moss, and soil, allowing recent terrestrial surveys to be considered alongside earlier investigations that focused primarily on aquatic habitats. We also described the morphology, ecology, and geographical distribution of eight species newly recorded in China and reported two putative new species. Chinese records were considered together with global information to place the observed distribution patterns in a broader geographical context. 

Results: A total of 257 bdelloid rotifer species, including subspecies, were recorded in China. Guangdong had the highest recorded richness, with 165 species, followed by Hunan with 85, Xizang with 72, and Guangxi with 71. Differences in recorded richness among provinces were influenced by survey intensity, indicating that the available records reflect variation in both species occurrence and research coverage. Leaf litter, moss, and soil supported records of 152, 135, and 86 species, respectively, demonstrating the substantial diversity documented in terrestrial habitats. Compared with previous surveys centered on aquatic environments, recent terrestrial investigations considerably expanded the known habitat occurrences and geographical distributions of Chinese bdelloid rotifers. The two suspected new species and eight new Chinese records further highlighted the contribution of these investigations to taxonomic knowledge. Chinese and global information revealed a general pattern of widespread distribution, localized concentrations of recorded richness, and uneven documentation, which was strongly influenced by sampling intensity. The rapid increase in the number of species recorded in China since 2017 primarily reflected broader survey coverage and the accumulation of taxonomic research, rather than providing evidence of a short-term change in species diversity. 

Conclusion: The integration of historical literature and recent surveys provides a more comprehensive account of bdelloid rotifer diversity and distribution in China and highlights the importance of terrestrial habitats in documenting this fauna. Nevertheless, geographical differences in recorded richness should be interpreted in relation to survey intensity, and increases in the cumulative species inventory should not be equated with temporal increases in biological diversity. Uneven documentation remains a major constraint on understanding distribution patterns across provinces and habitats. Standardized sampling in poorly surveyed regions and specialized habitats is therefore essential for improving the comparability and completeness of distribution records. Integrative taxonomy combining morphological observations with molecular evidence is also needed to resolve cryptic diversity and evaluate suspected new species. Overall, these approaches will provide a firmer foundation for clarifying the species composition and geographical distribution of Chinese bdelloid rotifers and for interpreting the biological patterns underlying the current record-based picture of their diversity.

Key words: Bdelloidea, species diversity, taxonomy, biogeographic distribution, species checklist