caa a22 4500 388017023 CHVBK 20180307124913.0 cr unu---uuuuu 161130e199809 xx s 000 0 eng 10.1017/S0022336000027153 doi S0022336000027153 pii (NATIONALLICENCE)cambridge-10.1017/S0022336000027153 Head Martin J. Department of Geology, Earth Sciences Centre, University of Toronto, Toronto, Ontario, M5S 3B1 Canada New goniodomacean dinoflagellates with a compound hypotractal archeopyle from the late Cenozoic: Capisocysta Warny and Wrenn, emend [Elektronische Daten] [Martin J. Head] Two new species of dinoflagellate are described from the upper Cenozoic of the North Atlantic region. They are assigned to the goniodomacean genus Capisocysta Warny and Wrenn, 1997 emend., whose archeopyle uniquely forms by the extensive and exclusive dissociation of hypocystal plates. Capisocysta lata new species is recorded from the upper lower Pliocene Coralline Crag Formation of eastern England, the lower and upper Pliocene of the subsurface Great Bahama Bank, and as a living cyst from Phosphorescence Bay, Puerto Rico. Capisocysta lyellii new species is reported from the Coralline Crag Formation of eastern England. Capisocysta provides the only unambiguous example of a hypocystal archeopyle in the order Gonyaulacales and the only example of a hypotractal archeopyle in the division Dinoflagellata. The spherical, proximate cysts have pre-formed lines of weakness that occur exclusively on the hypocyst, where they follow plate boundaries. Upon excystment, these sutures facilitate the separate release of plates 2-6″′, ps, 1p, and 1″″. Sulcal plates 1s and rs and postcingular plate 1″′ typically remain attached to the epicyst, forming a distinctive hyposulcal tab. The single antapical plate in C. lata is represented in C. lyellii by two plates (left and right first antapical homologues) that are released separately. Capisocysta has a tropical to warm temperate distribution today. It thrived and perhaps formed blooms in tropical carbonate platform environments of the Bahamas during the Pliocene, and might prove to be a useful indicator of very warm intervals within the Pliocene of higher latitude regions including the southern North Sea basin. To facilitate discussion of Capisocysta, several morphological terms have been modified or newly introduced. These terms more precisely describe archeopyle position and extent in dinoflagellates. Copyright © The Paleontological Society Journal of Paleontology Cambridge University Press 72/5(1998-09), 797-809 0022-3360 72:5<797 1998 72 JPA https://doi.org/10.1017/S0022336000027153 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0022336000027153 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Head Martin J. Department of Geology, Earth Sciences Centre, University of Toronto, Toronto, Ontario, M5S 3B1 Canada NATIONALLICENCE 773 0- Journal of Paleontology Cambridge University Press 72/5(1998-09), 797-809 0022-3360 72:5<797 1998 72 JPA CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge