New and interesting Eunotia (Bacillariophya) taxa from the Democratic Republic of the Congo, tropical central Africa

Abstract

Background and aims – Large-celled Eunotia species from tropical central Africa are documented in order to define morphological variation within species and to describe new or poorly documented taxa. Methods – Samples were collected from the Congo River between Kisangani and Bumba in the Democratic Republic of the Congo. These samples were prepared for diatom analysis and examined according to standard methods and documented using both light and scanning electron microscopy. Key results – A single population of Eunotia zygodon is used to demonstrate the high degree of change in gross cell morphology during its life cycle, changes previously observed in cultures of this genus. Cells of this taxon from each extremity of the reproductive cycle could be, and probably often were, placed in discrete taxa during sample analysis, especially as this taxon occurs rather infrequently. We also describe Eunotia leonardii as new to science. It has an undulate valve margin and is closely related to Eunotia serra and Eunotia georgii but differs in respect to overall cell size and the structure of the terminal raphe endings. The bi-undulate Eunotia papilio var. africana is raised to the rank of species and named Eunotia fuseyi as it is clearly a discrete taxon from E. papilio s. str.