1289 Elbrächter & al. • Agenda for Calcareous Dinoflagellate Research TAXON 57 (4) • November 2008: 1289–1303 INTRODUCTION The distinct character unifying calcareous dinoflagel- lates is the production of calcified exoskeletal structures during stages of their life cycle that are commonly inter- preted as hypnozygotes. They are well documented in the fossil record because of their high potential to fossilise (Keupp, 1981, 1987, 1991; Kohring, 1993; Hildebrand-Habel & Streng, 2003; Streng & al., 2004a) and are important in various palaeontological applications such as palaeoecol- ogy and palaeoclimatology (Vink & al., 2001; Esper & al., 2004; Meier & al., 2004a; Zonneveld & al., 2005). In micropalaeontology, all fossil dinoflagellates are usually termed cysts regardless of the actual function of the cells, which mostly can not be specified in fos- sils. Fensome & al. (1993: 6ff.) provide a comprehensive overview of such “cysts” and distinguish various possible functions of these cells. In calcareous dinoflagellates, two Establishing an Agenda for Calcareous Dinoflagellate Research (Thoracosphaeraceae, Dinophyceae) including a nomenclatural synopsis of generic names Malte Elbrächter 1 * , Marc Gottschling 2 , Tania Hildebrand-Habel 3 , Helmut Keupp 2 , Rolf Kohring 2 , Jane Lewis 4 , K.J. Sebastian Meier 5 , Marina Montresor 6 , Michael Streng 7 , Gerard J.M. Versteegh 8 , Helmut Willems 9 & Karin Zonneveld 9 1 Deutsches Zentrum für Marine Diversitätsforschung, Forschungsinstitut Senckenberg, Wattenmeerstation Sylt, Hafenstraße 43, 25991 List/Sylt, Germany. *melbraechter@awi-bremerhaven.de (author for correspondence) 2 Freie Universität Berlin, Institut für Geologische Wissenschaften – Fachrichtung Paläontologie, Malteser Straße 74-100, 12249 Berlin, Germany 3 University of Stavanger, Faculty of Science and Technology, 4036 Stavanger, Norway 4 University of Westminster, School of Biosciences, 115 New Cavendish Street, London W1W 6UW, U.K. 5 Christian-Albrechts-Universität zu Kiel, Institut für Geowissenschaften, Ludewig-Meyn-Str. 16, 24118, Kiel, Germany 6 Stazione Zoologica ‘A. Dohrn’, Villa Comunale, 80121 Napoli, Italy 7 Uppsala University, Department of Earth Sciences – Palaeobiology, Villavägen 16, 75236 Uppsala, Sweden 8 Universität Hamburg, Institut für Biogeochemie und Marine Chemie, Bundesstrasse 55, 20146 Hamburg, Germany 9 Universität Bremen, Fachbereich Geowissenschaften – Historische Geologie und Paläontologie, Postfach 330 440, 28334 Bremen, Germany Calcareous dinoflagellates are considered to be a monophyletic group of peridinoid taxa that have the potential to produce calcified exoskeletal structures during the life cycle, or that derive from such forms. Frequently, these calcareous bodies are excellently preserved in the fossil record and have received increased attention during the past three decades with regard to their use in biostratigraphy, climate and environmental reconstruction. Fossil and extant taxa have been classified in various, partly concurring, systematic concepts, using character complexes of the theca, cyst wall ultrastructure and archaeopyle/operculum morphology. The significance of such character complexes is briefly discussed in the light of molecular data that have been accumulated dur- ing the past decade. Over the years, the number of published taxonomic names has increased, partly due to nomenclatural changes. We propose that the entirety of calcareous dinoflagellates, and non-calcareous relatives derived from them, is accommodated in a single family of the order Peridiniales, the Thoracosphaeraceae, combining the former segregated taxonomic units Calciodinelloideae, a subfamily within Peridiniaceae, and Thoracosphaerales, a separate dinoflagellate order. As a result of a meeting of calcareous dinoflagellate spe- cialists, we outline major subjects that are in need of re-investigation and -evaluation (an Agenda for Calcare- ous Dinoflagellate Research). In order to contribute to a consistent and stable nomenclature and taxonomy of calcareous dinoflagellates, we list 97 published generic names assigned to known calcareous dinoflagellates in a nomenclatural synopsis, with species names indicating their types and information on type locality and stratigraphy. We evaluate the status of these names—whether validly published and, if so, whether legitimate—, a crucial first step for any revisionary work in the future. KEYWORDS: calcareous dinophytes, checklist, Thoracosphaeraceae