Observations on Hippodonta (Bacillariophyceae) in selected ancient lakes

This study provides an evaluation of the diversity and distribution of taxa belonging to the genus Hippodonta (Bacillariophyceae) in selected ancient lakes from different geographical regions of the world. The lakes considered are: Lakes Ohrid, Prespa and Dojran from Macedonia, Lake Tanganyika, Tanzania, Lake Turkana, Kenya and Lake Baikal, Russia. In total, there are 34 Hippodonta taxa. Of these, 21 are described as new, 20 species and one variety. The primary morphological features of each taxon are provided and formal descriptions are given for all new taxa. The distinctive characters distinguishing similar taxa are noted. The genus is most diverse in Lake Baikal with 13 taxa, of which four are described as new species (Hippodonta acuta, H. certa, H. communis and H. pulchra). Lake Tanganyika has six taxa, all of which are described as new (H. angustata, H. avittatiformis, H. cocquytiae, H. conspicua, H. crassa and H. radiata). Lake Turkana has only one taxon, also described as new (H. minuta). In the Macedonian old tectonic lakes, seven taxa were found in Lake Ohrid, with five described as new (H. abunda, H. humboldtiana, H. latelanceolata, H. naviculiformis and H. subrostrata), five taxa were found in Lake Prespa, all of which are described as new (H. affinis, H. costulatiformis var. densistriata, H. exigua, H. media and H. rostratoides), and three known taxa were found in Lake Dojran.