Apex/anterior end | front of dinoflagellate when swimming, usually pointed. Almost always contains the archaeopyle. |
Antapex/posterior end | rear of dinoflagellate when swimming, usually flaring. |
Ventral side | side of dinoflagellate with longitudinal flagellum and sulcus. |
Dorsal side | side opposite longitudinal flagellum and sulcus. |
Calcisphere | hollow, typically spherical, calcareous nannofossil. Whereas coccospheres are composite structures formed of numerous coccoliths calcispheres possess a continuous wall. |
Cyst | wall formed around dinoflagellate during non-motile, non-vegetative, stage. These often show paratabulation but are continuous structures, except for the archaeopyle if present. Most calcispheres are thought to be cysts, however, the thoracosphere of Thoracosphaera heimii is formed during the vegetative stage and so is not a cyst. |
Dinoflagellate | informal taxon-based term for member of the phylum Dinophyta. |
Theca | non-resistant organic wall of motile vegetative stage of dinoflagellates, composite structures formed of plates. |
Thoracosphere | informal taxon-based term for calcisphere formed by Thoracosphaera. N.B. T. heimii has a wall structure of large elements (ca. 1 µm) with their c-axes tangential to the wall, and randomly aligned. |
Oblique/Obliquipithonelloid | formed of elements with their c-axes oblique to the wall and variably aligned relative to each other (e.g. Obliquipithonella multistrata). | |
Pithonelloid | formed of elements with their c-axes oblique to the wall and sub-parallel to each other (e.g. Pithonella sphaerica, P.ovalis). | |
Radial/Orthopithonelloid | formed of elements with their c-axes perpendicular to the wall (e.g. Calciodinellum, Rhabdothorax). | |
Tangential | formed of elements with their c-axes tangential to the wall (e.g. Fuetterella conforma, Thoracosphaera heimii). |
Archaeopyle | opening for excystment. |
Operculum | plate covering the archaeopyle. |
Paratabulation | structures on the cyst of a dinoflagellate reflecting the tabulation of the theca. Paratabulation may be developed on the inner or the outer surface of calcispheres. |
Cingulum | sub-equatorial channel occupied by the transverse flagellum. |
Sulcus | furrow occupied by longitudinal flagellum. |
Horn | protrusion from either end of dinoflagellate. |
Holotabulate | paratabulation of ridges or edges on the cyst corresponding to plate boundaries on the theca. |
Intratabulate | paratabulation of processes on the cyst corresponding to plates on the theca. |
Cingulotabulate | paratabulation confined to cingulum and archaeopyle. |
Cryptotabulate | paratabulation confined to archaeopyle. |