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Background China is an important biogeographical zone in which the genetic legacies of the Tertiary and Quaternary periods are abundant, and the contemporary geography environment plays an important role in species distribution. Therefore, many biogeographical studies have focused on the organisms of the region, especially zooplankton, which is essential in the formation of biogeographical principles. Moreover, the generality of endemism also reinforces the need for detailed regional studies of zooplankton. Bosmina , a group of cosmopolitan zooplankton, is difficult to identify by morphology, and no genetic data are available to date to assess this species complex in China. In this study, 48 waterbodies were sampled covering a large geographical and ecological range in China, the goal of this research is to explore the species distribution of Bosmina across China and to reveal the genetic information of this species complex, based on two genetic markers (a mtDNA 16S and a nuclear ITS). The diversity of taxa in the Bosmina across China was investigated using molecular tools for the first time. Results Two main species were detected in 35 waterbodies: an endemic east Asia B. fatalis , and the B. longirostris that has a Holarctic distribution. B. fatalis had lower genetic polymorphism and population differentiation than B. longirostris. B. fatalis was preponderant in central and eastern China, whereas B. longirostris was dominated in western China. The third lineage ( B. hagmanni ) was only detected in a reservoir (CJR) of eastern China (Guangdong province). Bosmina had limited distribution on the Tibetan plateau. Conclusions This study revealed that the biogeography of Bosmina appear to be affected by historical events (Pleistocene glaciations) and contemporary environment (such as altitude, eutrophication and isolated habitat). Electronic supplementary material The online version of this article (10.1186/s12862-019-1474-4) contains supplementary material, which is available to authorized users.

The relationship between crustacean zooplankton community and environmental factors remains a hot topic in eutrophication bio-monitoring subject. Most water bodies in the Yangtze River delta are mesotrophic/eutrophic, which has attracted much attention from ecologists. Nevertheless, previous studies on crustacean zooplankton community in this region only focused on their relation to physicochemical factors excluding phytoplankton. In this study, the crustacean zooplankton abundance and environmental factors (physicochemical factors and phytoplankton abundance) were investigated in Spring, Summer, Autumn and Winter in 13 waterbodies (8 lakes and 5 reservoirs) located in the Yangtze River delta. Results showed that NO2−–N and TN in Spring, SD and TP in Summer had significant difference (P < 0.05) between 8 lakes and 5 reservoirs. That may be related to microbial communities and macrophytes. All 13 studied water bodies were dominated by cyanophyta, whose Microcystis may determine the dominance of Bosmina fatalis. Moreover, eutrophic level should be in relation to the significant difference of plankton between 8 lakes and 5 reservoirs. Finally, five factors (cyanophyta, SD, WT, pH and DO) were significantly correlated with crustacean zooplankton abundance. That indicated the metabolism, reproduction, development and competitors of crustacean zooplankton were affected by these five factors. This research provided basic data of the 13 water bodies and studied the relationship between zooplankton and physicochemical factors as well as phytoplankton, providing scientific basis for the monitoring of eutrophic waterbodies located in the Yangtze river delta.