A revision of the late jurassic dinoflagellate cysts ambonosphaera? Staffinensis (gitmez 1970) comb. nov., and senoniasphaera jurassica (gitmez & sarjeant 1972) Lentin & Williams 1976

The type material of “Meiourogonyaulax”; staffinensis Gitmez 1970 and Hexagonifera sp. Gitmez 1970 (later “H.” jurassica Gitmez & Sarjeant 1972) from the earliest Kimmeridgian (Late Jurassic) of Scotland and England has been restudied. The former species is a small (42-51 (im), camocavate to circumcavate gonyaulacacean cyst with an apical archeopyle and a median parasulcus and is herein questionably attributed to Ambonosphaera Fensome 1979. Sirmiodiniopsis frisia (Raynaud 1978) Lentin & Williams 1981 is deemed to be a subjective junior synonym of Ambonosphaera? staffinensis. Senoniasphaera jurassica (Gitmez & Sarjeant 1972) Lentin & Williams 1976 is a larger (63-105 μm), circumcavate species also with a gonyaulacacean paratabulation and an apical archeopyle, but with a markedly offset parasulcal notch. The specific diagnoses of these two Late Jurassic species are emended to include new information on morphology and paratabulation.