A review of the Jurassic dinoflagellate cyst genus Gonyaulacysta Deflandre 1964 emend. nov.

The Middle–Late Jurassic gonyaulacacean dinoflagellate cyst genus Gonyaulacysta is characterised by an epicyst which around twice the length of hypocyst. sulcus L-type and may be slightly sigmoidal in shape, but never S-type sensu stricto. forms with sulcuses have developed into species sulcuses. jurassica , holotype nomenclatural type genus, had a global distribution. A total 151 been assigned to although 126 these transferred other genera. Prior this contribution, 25 were accepted current Lentin Williams Index. This herein reduced eight 18 are are: adecta stat. nov., emend. nov.; australica comb. ceratophora ; desmos dualis fenestrata longicornis nov. These form closely related plexus, distinguished on differences cavation style, sutural crests/ridges size apical horn. All except reliable marker taxa. Our main taxonomic proposals involve elevation all subspecies varieties here retained rank, or their synonymisation. avoids cumbersome infraspecific names. exhibits substantial provincialism; for example confined Oxfordian–Kimmeridgian Boreal Realm. adecta, present Bathonian Oxfordian Laurasia surrounding areas. Three species, australica, fenestrata, restricted Tithonian Australasia. cosmopolitan both exhibit overall increases throughout Kimmeridgian Europe. • unique morphology described. Eight recognised herein. previous names eliminated. Seven markers. Substantial provincialism recognised.