Dinoflagellate cyst terminology: a discussion and proposals

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Abstract
This paper constitutes an attempt to stabilize and expand the descriptive terminology applied to dinoflagellate cysts. The "para" terminology of Evitt et al. (1977, Geol. Surv. Pap. Geol. Surv. Can. 76) is critically reviewed; use of the terms "paraplate," "parasuture," "paratabulation" is endorsed, but the terms "paracingulum" and "parasulcus" and their derivatives are rejected. A new terminology is proposed to characterize the fashions in which paratabulation is expressed. The terms used to define the principal cyst lineages are redefined and their interrelationships summarized. Continued use of the terms "epitract" and "hypotract," "endoblast," and "periblast" is urged.In the course of a discussion of paraplate terminology, the problem of deciding what constitutes a plate or paraplate "series" is considered and a definition attempted. New definitions are presented thereafter for "preapical," "postapical," and "preantapical" paraplates and new names are proposed for the two further additional series present on some rhaetogonyaulacoid cysts. The problems of designation presented by the last apical and first postcingular paraplates of gonyaulacoids are discussed.Revised definitions, in accord with present usage, are proposed for the cyst categories "proximate," "proximochorate," and "chorate." Revised definitions are also presented for five existing types of proximochorate and chorate cysts and three new categories are distinguished. The taxonomic problem presented by membranate cysts is discussed. The various types of cavate cyst are illustrated and nine new terms proposed to identify types not hitherto distinguished. Contraction of the terms "endoarchaeopyle" and "periarchaeopyle," respectively, to "endopyle" and "peripyle," is suggested; and simpler names are proposed for the cingulum and sulcus on endoblast and periblast.The terminology applied to the small preformed openings in cavate cysts is reviewed and arbitrary limits suggested for use in designating horn lengths. A new descriptive terminology for crests and septa is presented. The terminology applied to processes and process tips is reconsidered, additional terms being proposed.

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