Areoligeracean dinoflagellate cysts from the upper Campanian (Upper Cretaceous) of Hornby Island, British Columbia, Canada

Twenty-nine mudstone samples from coastal exposures of the upper Campanian Northumberland Formation on Hornby Island, British Columbia, Canada, have yielded diverse assemblages of exceptionally well-preserved dinoflagellate cysts belonging to the family Areoligeraceae. In total, at least 11 species belonging to eight genera occur throughout the studied section. Emendations are proposed for the genera <i>Canningia</i>, <i>Canninginopsis</i>, <i>Circulodinium</i>, <i>Cyclonephelium</i> and <i>Senoniasphaera</i>. The new species <i>Canningia diastatikos</i> sp. nov. is proposed. The assemblages include one species complex, which we refer to as the ‘<i>Areoligera volata</i> complex’, that exhibits morphological intergradation between forms typical of <i>Areoligera coronata</i> and <i>Areoligera volata</i>. It is postulated that morphological intergradation may reflect ecophenotypic variability which may present utility for palaeoenvironmental reconstructions.