Observations on the Jurassic dinoflagellate cyst Nannoceratopsis ambonis Drugg, 1978

The Lower to Middle Jurassic dinoflagellate cyst Nannoceratopsis ambonis Drugg, 1978 is here divided into two species, Nannoceratopsis ambonis Drugg, 1978 emend. nov. and N. dictyambonis sp. nov. on the basis of differing saggital band morphologies. The two species do not appear to intergrade morphologically and have differing stratigraphical ranges, N. ambonis emend. nov. being found from the Upper Pliensbachian ( spinatum Zone) to the Upper Bajocian and N. dictyambonis sp. nov. being restricted to the uppermost Toarcian ( moorei Subzone: levesquei Zone) – Lower Bajocian ( laeviuscula Zone) interval.