New data on morphology, distribution, and relationship of two Asian endemics Netzelia tuberspinifera and Netzelia mulanensis (Amoebozoa: Arcellinida) co-existing in the largest natural freshwater lake of Vietnam

摘要

Data on the distribution and species-environment relationships of rare and endemic species of protists in Asian tropical waterbodies could provide valuable information for better understanding of auto- and synecology of microbes in tropical ecosystems. We studied the morphology, abundance and distribution of two rare endemic species of testate amoebae Netzelia tuberspinifera and Netzelia mulanensis co-existing in Ba Be Lake (Bac Kan province), the largest natural lake of Vietnam. The results of NMDS and ANOSIM analyses showed insignificant difference by measured physicochemical parameters of water between nearshore and open water areas of the lake. Difference of abundances of each studied species between nearshore and open water areas of Ba Be Lake was not statistically significant. Additionally, abundances of N. tuberspinifera and N. mulanensis were weakly and insignificantly correlated at the time of investigation. The relation between environmental parameters and species distribution was investigated using a redundancy analysis (RDA) following forward selection procedure. The first and second RDA axes explained together 67% of the total variance in the data. Forward selection identified that water temperature and turbidity should be retained for the parsimonious RDA model. It is suggested that water turbidity should be considered in the next studies of relation between environmental variables and testate amoeba data. There were statistically significant differences in morphology between Vietnamese and Chinese populations of both investigated species.