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

Riding, James B. ORCID: https://orcid.org/0000-0002-5529-8989; Mariani, Erica; Fensome, Robert A.. 2022 A review of the Jurassic dinoflagellate cyst genus Gonyaulacysta Deflandre 1964 emend. nov. Review of Palaeobotany and Palynology, 299, 104605. https://doi.org/10.1016/j.revpalbo.2022.104605

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Official URL: http://dx.doi.org/10.1016/j.revpalbo.2022.104605

Abstract/Summary

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

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1016/j.revpalbo.2022.104605
ISSN:	00346667
Date made live:	17 Mar 2022 14:49 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/532280

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1016/j.revpalbo.2022.104605

ISSN:

00346667

Date made live:

17 Mar 2022 14:49 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/532280