The First Data on Testate Amoebae in the Coco River in Quang Nam and Da Nang Provinces, Vietnam

The first data on the species diversity of testate amoebae of the Coco River in the provinces of Quang Nam and Da Nang (Vietnam) are presented. A total of 55 species and subspecies of testate amoebae belonging to nine genera and six families have been identified in 28 samples. Species diversity of testate amoebae in plankton is higher than in benthic samples. Centropyxis aculeata (64.3%), Netzelia wailesi (39.3%), Difflugia acuminata (32.1%), Arcella discoides scutelliformis (28.6%), and Lesquereusia modesta (28.6%) are characterized by the highest frequency of occurrence. Difflugia (25), Arcella (12), Centropyxis (5), and Netzelia (4) are the most species-rich genera. The species accumulation curve based on the entire dataset is unsaturated and is described by the equation y = 12.56N0.46. The average species richness of testate amoebae per sample in plankton (13.0 ± 3.1) is statistically higher than in benthic samples (1.8 ± 1.5) (p < 0.001). The result of the redundancy analysis shows that the studied hydrochemical water parameters (temperature, pH, dissolved oxygen, electrical conductivity, and salinity) explain only 31.6% of the variation of testate amoeba diversity; the first and second axes explain 11 and 10.2% of this variation, respectively.