The dinoflagellate cyst genera Achomosphaera Evitt 1963 and Spiniferites Mantell 1850 in Pliocene to modern sediments: a summary of round table discussions

We present a summary of two round-table discussions held during two subsequent workshops in Montreal (Canada) on 16 April 2014 and Ostend (Belgium) on 8 July 2015. Five species of the genus Achomosphaera Evitt 1963 Evitt WR. 1963. A discussion and proposals concerning fossil dinoflagellates, hystrichospheres, and acritarchs, I. National Academy of Sciences, Washington, Proceedings. 49(2):158–164.[Crossref], [PubMed], [Web of Science ®], , [Google Scholar] and 33 of the genus Spiniferites Mantell 1850 emend. Sarjeant 1970 Sarjeant WAS. 1970. The genus Spiniferites Mantell, 1850 (Dinophyceae). Grana. 10(1):74–78.[Taylor & Francis Online], , [Google Scholar] occuring in Pliocene to modern sediments are listed and briefly described along with remarks made by workshop participants. In addition, several holotypes and topotypes are reillustrated. Three species previously assigned to Spiniferites are here considered/accepted as belonging to other genera: Impagidinium inaequalis (Wall and Dale in Wall et al. 1973 Wall D, Dale B, Harada K. 1973. Descriptions of new fossil dinoflagellates from the Late Quaternary of the Black Sea. Micropaleontology. 19(1):18–31.[Crossref], , [Google Scholar]) Londeix et al. 2009 Londeix L, Herreyre Y, Turon J-L, Fletcher W. 2009. Last Glacial to Holocene hydrology of the Marmara Sea inferred from a dinoflagellate cyst record. Rev Palaeobot Palynol. 158(1-2):52–71.[Crossref], [Web of Science ®], , [Google Scholar], Spiniferites? rubinus (Rossignol 1962 Rossignol M. 1962. Analyse pollinique de sédiments marins quaternaires en Israël II. - Sédiments pleistocènes. Pollen et Spores. 4:121–148. [Google Scholar] ex Rossignol 1964 Rossignol M. 1964. Hystrichosphères du Quaternaire en Méditerranée orientale, dans les sédiments Pléistocènes et les boues marines actuelles. Revue de Micropaléontologie. 7:83–99. [Google Scholar]) Sarjeant 1970 Sarjeant WAS. 1970. The genus Spiniferites Mantell, 1850 (Dinophyceae). Grana. 10(1):74–78.[Taylor & Francis Online], , [Google Scholar], and Thalassiphora balcanica Balteş 1971. This summary forms the basis for a set of papers that follows, where points raised during the workshops are explored in greater detail.