Preface Prof. Dr. Biol. Sc. Dobrina N. Temniskova-Topalova (A life dedicated to the students) by Dimitar Vodenicharov, Kalina Manoylov & Nadja Ognjanova Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan by N. I. Strelnikova, J. P. Kociolek & E. Fourtanier Species of the genus Terpsinoe Ehrenberg (Bacillariophyta) from the Miocene of Middle Russia, Moldova, and Ukraine by Tatyana F. Kozyrenko Comparison of seven species of Navicula sensu stricto. Six species described as new to science from Miocene lacustrine deposits in Bulgaria and Romania by Horst Lange-Bertalot & Ditmar Metzeltin Evolution of the extinct genera belonged to the family Stephanodiscaceae (Bacillariophyta) during the last eight million years in Lake Baikal by Galina Khursevich A new Cymbella from the Neogene in Bulgaria and its stratigraphic significance by Nadja Ognjanova-Rumenova & Ditmar Metzeltin Nitzschia toskalensis sp. nov. a new diatom (Bacillariophyceae) from the sediments of Toskaljavri, northwestern Finland by Paul B. Hamilton Distribution of resting spores of Eunotia soleirolii and Meridion circulare var. constrictum (Bacillariophyta) in sediments of peat bogs from Mt. Central Sredna Gora, Bulgaria by Rosalina Stancheva Taxonomic Status of Detonia Frenguelli and the Establishment of Detonia dobrinae sp. nov. (Bacillariophyceae) by Ioanna Louvrou, Daniel Danielidis & Athena Economou-Amilli Staurosira incerta (Bacillariophyceae) a new fragilarioid taxon from freshwater systems in the United States with comments on the structure of girdle bands in Staurosira Ehrenberg and Staurosirella Williams et Round by Eduardo A. Morales Achnanthidium temniskovae sp. nov., a new diatom from the Mesta River, Bulgaria by Plamen Ivanov & Luc Ector A new Gyrosigma species from lakes Prespa and Ohrid by Zlatko Levkov, Svetislav Krstic & Teofil Nakov Diatom species composition from the river Iskar in the Sofia region, Bulgaria by Plamen Ivanov, Emilia Kirilova & Luc Ector Chara corfuensis J. Gr. ex Fil. 1937 (Characeae) an endemic species of Balkan Peninsula, rare and globally endangered by Jelena Blazencic First record of the tropical invasive alga Compsopogon coeruleus (Balbis) Montagne (Rhodophyta) in Flanders (Belgium) by Maya P. Stoyneva, Koenraad Vanhoutte & Wim Vyverman Initial observations on uniparental auxosporulation in Muelleria (Frenguelli) Frenguelli and Scoliopleura Grunow (Bacillariophyceae) by Mark B. Edlund & Sarah A. Spaulding Effect of abscisic acid on host susceptibility during different ontogenetic phases of the host alga in the pathosystem Scenedesmus acutus Phlyctidium scenenedesi by Irina D. Pouneva & Christo Christov Diatom succession in the Ferdynandovian interglacial lacustrine deposits of Poland by Barbara Marciniak Environment variation in the Black Sea region during the Late Quaternary based on fossil diatoms by A. P. Olshtynskaya Late Pleistocene/Holocene dinoflagellate cyst assemblages from the Southwestern Black Sea shelf by Mariana Filipova-Marinova Diatoms as indicators of the influence of the Vistula river inflow on the Gulf of Gdansk during the Holocene by Katarzyna Stachura-Suchoples Diatom flora diversity in the strongly eutrophicated and ?-mesosaprobic waters of the Szczecin Lagoon, NW Poland, southern Baltic Sea by Malgorzata Bak, Andrzej Witkowski & Horst Lange-Bertalot Use of nonparametric multiplicative regression for modeling diatom habitat: a case study of three Geissleria species from North America by Marina G. Potapova & Diane M. Winter Density-dependent algal growth along N and P nutrient gradients in artificial streams by Kalina M. Manoylov & R. Jan Stevenson Atypical Tabularia in Coastal Lake Erie, USA by E. F. Stoermer & N. A. Andresen refining diatom indicators for valued ecological attributes and development of water quality criteria by R. Jan Stevenson.