Novel Species of Centrohelid Heliozoans (Centroplasthelida) for Freshwaters of Central and Southern Vietnam

The species diversity, distribution, and morphological features of centrohelid heliozoans (Centroplasthelida) (Haptista: Centroplasthelida Febvre-Chevalier et Febvre, 1984) from freshwaters of Central and Southern Vietnam have been studied using scanning electron microscopy (SEM). Twelve species, belonging to Acanthocystidae, Choanocystidae, Pterocystidae, Raphidiophryidae, and Raphidocystidae families, have been found. Eleven species are new for Vietnam. Illustrated descriptions of species found are provided. The morphology of investigated centrohelids mainly corresponds to published data; however, some differences have been shown. The diversity of heliozoans in Vietnam and other regions has been discussed.