Late Quaternary freshwater dinoflagellate cysts from the British Isles

Abstract. Two species of peridinioid dinoflagellate cyst are described from Late Quaternary lacustrine and fluvial deposits in England and Scotland. Saeptodinium skipseaense sp. nov. has a bipesoid tabulation and a hemiepicystal archaeopyle. Colonsaydinium psilatum gen. et sp. nov. has a compound archaeopyle interpreted as 213P (1–2i 3–5″). The morphology of the archaeopyle suggests that this may be the cyst of a species with cinctoid tabulation. Both taxa are found only in sediment laid down in base-rich, non-turbulent, relatively deep fresh water.