C Nova Hedwigia, Beiheft 143, p. 141–158 Stuttgart, July 2014 © 2014 J. Cramer in der Gebr. Borntraeger Verlagsbuchhandlung, Stuttgart, Germany www.borntraeger-cramer.de DOI 10.1127/1438-9134/2014/008 1438-9134/2014/008 $ 4.50 Observations on Caloneis Cleve (Bacillariophyceae) species from the ancient lakes Ohrid and Prespa Zlatko Levkov 1 * and David M. Williams 2 1 Institute of Biology, Faculty of Natural Sciences, Gazi Baba bb, Skopje, R. Macedonia 2 Department of Life Sciences, Natural History Museum, Cromwell Road, London, United Kingdom * Corresponding author: zlevkov@iunona.pmf.ukim.edu.mk With 110 figures Abstract: The genus Caloneis Cleve is widely spread in freshwater and brackish water habitats. The recent observations of oligotrophic lakes show great diversity of the genus with the presence of many unidentified taxa. Among the lakes, the ancient lakes have a specific place because of their high level of diversity and endemism. Lakes Ohrid and Prespa, as one of the oldest lakes, has proven to be one of the hotspots for diatom diversity with more than 900 recognized taxa and more than 150 potentially endemic species. This study presents a detailed account of Caloneis in Lakes Ohrid and Prespa, providing additional information on some of the previously described putative endemic taxa from both lakes. Eight of observed species have unique morphological features and are described as new: Caloneis distinguenda sp. nov., Caloneis gibba sp. nov., Caloneis affinis sp. nov., Caloneis amoena sp. nov., Caloneis strelnikovae sp. nov., Caloneis claviculiformis sp. nov., Caloneis minuta sp. nov. and Caloneis angustata sp. nov. Key words: Diatoms, Caloneis, Lakes Ohrid, Prespa, taxonomy, new species Introduction Caloneis Cleve was introduced by Cleve as a subgroup of Navicula (in Cleve & Grove 1891, p. 66). Among the new species described by Cleve, two were assigned to Caloneis, Navicula (Caloneis) biclavata Cleve and Navicula (Caloneis) oemula var. ? major Cleve, with eight additional names to be included. However, a valid description was not provided until a few years later, appearing in Cleve’s Synopsis of the Naviculoid Diatoms (Cleve 1894, p. 46), where he included some 74 species with more than 60 infraspecific taxa (varieties and forms), from marine, brackish and freshwater environments. Prior to the publication of this valid generic description, Caloneis kinkeriana Truan (in Cleve 1892, p. 76, fig. 12: 5) was described and “Caloneis wardii” noted, but not described, by Terry (1892. p. 231); both names were included in Cleve’s Synopsis (Cleve 1894, p. 65 and p. 57, respectively). Cleve (1894) did not identify a generitype nor was any reference made to the subgenus outlined in Cleve & Grove (1891, p. 66). Boyer was the first to designate a generitype, choosing Navicula amphisbaena Bory (Boyer 1927, p. 306). A search of the CAS Catalogue of Diatom Names (Fourtanier & Kociolek 2013) yielded some 880 names in Caloneis introduced from 1894 (the date of Cleve’s detailed account) to 2007 (Levkov et al. 2007, Metzeltin & Lange-Bertalot 2007, Novelo et al. 2007, Guiry & Guiry 2012 lists only just over 300 names – but their records finish in 2005). Taking into account the fact that both databases have their own idiosyncrasies and these figures represent numbers of names rather than taxa, Caloneis is still a large genus. Nevertheless, it has been subdivided in a few ways. There has been some discussion as to whether Caloneis is a distinct taxon (genus) separate from the closely related genus Pinnularia. A conclusion reached by Mann was that “the genus [Caloneis] appears to possess no morphological synapomorphies [uniquely derived characters] and cannot be satisfactorily diagnosed versus Pinnularia” (Mann 2001, p. 29). While morphological