Biogeography and morphology of a poorly known diatom Dorofeyukea rostellata (Hustedt) Kulikovskiy & Kociolek Zsuzsa Trábert 1,2,* , Krisztina Buczkó 1,3 , Gábor Borics 4 , Marija Gligora Udovič 5 , Balasubramanian Karthick 6 , Luc Ector 7 , Angéla Földi 1,2 , Keve T. Kiss 1 and Éva Ács 1 1 MTA Centre for Ecological Research, Danube Research Institute, 1113 Budapest, Karolina út 29, Hungary. 2 Eötvös Loránd University, Doctoral School of Environmental Sciences, 1117 Budapest, Pázmány Péter sétány 1/A, Hungary. 3 Hungarian Natural History Museum, Department of Botany, 1087 Budapest, Könyves Kálmán krt. 40, Hungary. 4 MTA Centre for Ecological Research, Danube Research Institute, Department of Tisza River Research, 4026 Debrecen, Bem tér 18/c, Hungary. 5 Department of Biology, Faculty of Science, University of Zagreb, 10000 Zagreb, Rooseveltov trg 6, Croatia. 6 Biodiversity & Paleobiology Group, Agharkar Research Institute, G.G. Agarkar Road, Pune – 411004 India. 7 Environmental Research and Innovation Department (ERIN), Institute of Science and Technology (LIST), 4422 Belvaux, 41 rue du Brill, Luxembourg. * Corresponding author: trabert.zsuzsa@okologia.mta.hu Received: 04/04/18 Accepted: 29/01/19 ABSTRACT Biogeography and morphology of a poorly known diatom Dorofeyukea rostellata (Hustedt) Kulikovskiy & Kociolek Dorofeyukea rostellata is a rare and poorly known representative of Dorofeyukea genus. To date, this taxon has only been recorded only outside of Europe. In two Croatian lakes, we found a diatom in appearance similar to Dorofeyukea rostellata and within corresponding physical and chemical conditions. Due to the uncertain taxonomical position of this taxon, type material of Dorofeyukea rostellata and a closely related species, Navicula grimmeioides, were analysed by means of light and scanning electron microscopy. Upon a detailed investigation, we could clearly distinguish the Croatian population from N. grimmeioides. However, the Croatian population and the type material of D. rostellata differed only in minor characteristics. The most obvious difference is the shape of areolae. Nevertheless, differences between the shapes of the areolae can be caused by the degree of silicification, which often depends on the environmental conditions. Since almost every other characteristic of the Croatian population overlapped with that of the type material of D. rostellata we identified it as D. rostellata. Additionally, scanning electron microscopy analyses also revealed that N. grimmeioides belongs to the genus Dorofeyukea, so its new combi- nation was proposed. Key words: type material, Dorofeyukea rostellata, Navicula grimmeioides, calcareous habitat, new combination RESUMEN Biogeografía y morfología de una diatomea poco conocida Dorofeyukea rostellata (Hustedt) Kulikovskiy & Kociolek Dorofeyukea rostellata es un representante raro y poco conocido del género Dorofeyukea. Hasta la fecha, esta especie solo ha sido registrada fuera de Europa. En dos lagos croatas, encontramos una diatomea en apariencia similar a Dorofeyukea rostellata y en las condiciones físicas y químicas correspondientes. Debido a la incierta posición taxonómica de este taxón, el material tipo de Dorofeyukea rostellata y una especie estrechamente relacionada, Navicula grimmeioides, se analizaron mediante microscopía de luz y electrónica de barrido. Tras una investigación detallada, pudimos distinguir claramente la población croata de N. grimmeioides. Sin embargo, la población croata y el tipo de material de D. rostellata diferían solo en características menores. La diferencia más obvia es la forma de las areolas. Sin embargo, las diferencias pueden deberse al grado de silicificación, que a menudo depende de las condiciones ambientales. Como casi todas las demás características de Limnetica, 38(2): 743-758 (2019). DOI: 10.23818/limn.38.43 © Asociación Ibérica de Limnología, Madrid. Spain. ISSN: 0213-8409