New Eunotia taxa in core samples from Lake Panch Pokhari in the Nepalese Himalaya

Abstract

During a survey of the diatom flora from a sediment core from Lake Panch Pokhari in the Nepalese Himalaya, four new Eunotia species were recorded and described: E. igorii Krstić, Levkov & Pavlov, E. zechii Krstić, Levkov & Pavlov, E. panchpokhariensis Krstić, Levkov & Pavlov and E. paramuscicola Krstić, Levkov & Pavlov. Detailed morphological descriptions of the taxa are given based on both light and scanning electron microscopy. The morphological features of each taxon were compared with similar taxa. Eunotia igorii is similar to South American, neotropical species which are larger in size and have more coarsely striated valves. Furthermore, an additional distinctive feature of E. igorii is the presence of prominent spines throughout the length of the valve margins. Eunotia zechii has three weak undulations on the dorsal valve margin, in contrast to the similar taxa E. fennica (Hustedt) Lange-Bertalot and E. neoborealis Lange-Bertalot. Eunotia panchpokhariensis has quite narrow and strongly curved valves with a large number of undulations (six or seven) on the dorsal margin. Taxa with similar morphological features are rarely found, and those with five or more dorsal undulations have larger valves. Eunotia paramuscicola also resembles E. panchpokhariensis in valve outline, but it has fever dorsal undulations and they are more uneven. The uneven expression and position of the dorsal undulations and the variable protraction of the valve ends, clearly set apart E. paramuscicola from its allied taxa. With the exception of E. paramuscicola, the three other new Eunotia species have so far not been found during extensive surveys in the Nepalese Himalaya.