Two new species of Vexillarius (Prymnesiophyceae) from the eastern Indian Ocean

Seawater samples from the lower photic zone, obtained from shallow hydrocasts during an investigation of the eastern Indian Ocean, revealed the presence of two new species of the coccolithophorid genus Vexillarius: V. iaculifera sp. nov. and V. cereus sp. nov. Both possess dimorphic coccospheres: simple dishlike body coccoliths and coccoliths with an elongate, quadrangular central appendage. The main difference between these species and the type species, V. cancellifer, is the appendage shape: flaring (V. cancellifer), dart-shaped (V. iaculifer), or tapered (V. cereus). Furthermore, a recently described genus and species (Porsildia acerviphora) from the Arctic closely resembles V. cereus, but differs in having ‘irregularly piled elements' in the central area that are not connected to the body coccolith wall. Since it possesses the characteristic features of Vexillarius, it is transferred to the genus as V. acerviphora comb. nov. It is believed that Vexillarius is closely related to Turrilithus a...