Taxonomic remarks on five centric-diatom species (Bacillariophyta) occurring rarely in Korean inland waters

Abstract

In searching for freshwater diatoms, five poorly known centric diatom species in South Korea were discovered. They were collected from different sources in the type and size of water bodies. Aulacoseira scalaris was collected from a small reservoir with few pollutants, Aulacoseira subborealis and Cyclostephanos delicatus from highly eutrophic streams, and Spicaticribra kingstonii from both a small reservoir and a large lake. Edtheriotia shanxiensis has been found in a river system that flows through limestone areas and has relatively low pollution. They are nanoplanktons with a diameter of less than 20 µm, and because there are many neighboring taxa with similar valve morphology, they were closely examined and compared with previously reported specimens under light and electron microscopy. In particular, C. delicatus showed a wide range of morphological variations because the interstrial ribs are largely bifurcated on the mid-valve. In addition, morphological comparisons between S. kingstonii and its related three species are intensively reviewed.