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Gordiacysta coronata
Gordiacysta coronata Miles, 1990
Holotype: Miles, 1990, pl.3, figs.1-2
Locus typicus: Offshore Namibia, S Atlantic
Stratum typicum: Late Albian
Original diagnosis: Miles, 1990, p. 88
Chorate dinoflagellate cyst with subspherical to ovoidal main body, composed of a smooth autophragm which is developed into a short, rounded apical horn. Three groups of ribbon-like processes arise from the autophragm in the apical, precingular/postcingular, and antapical series. The majorprocesses are mainly arcuate in section, and are linked distally by trabeculae, also of arcuate section, according to the arrangement described for the genus. The nature of the processes and trabeculae is variable. In smaller specimens, the length of the processes is approximately 1/4 of the main body diameter, and both processes and trabeculae are broad, giving the cyst a compact appearance (Plate 3, figs. 5-7). Larger specimens develop relatively longer processes, approximately one-half the main body diameter, and both processes and trabeculae are narrow, imparting a more expansive and open appearance to the cyst (Plate 3, figs. 1-4). Thread-like and tenuous subsidiary processes are inconsistently developed, most frequently in the area of the archeopyle. The antapical processes coalesce to form a conical horn that is closed at its tip. A free, single-plate, precingular archeopyle is developed. No operculum was observed.
Dimensions. Minimum (average) maximum: overall length 45(53)59 Ám, overall width 43(64)89 Ám; main body length 30(37)44 Ám, body width 27(37)47 Ám; apical horn length 3-4 Ám; apical crown length 7(11)14 Ám; antapical horn length 8(12)14 Ám; trabeculae width 2(3)5 Ám.
Holotype: Miles, 1990, pl.3, figs.1-2
Locus typicus: Offshore Namibia, S Atlantic
Stratum typicum: Late Albian
Original diagnosis: Miles, 1990, p. 88
Chorate dinoflagellate cyst with subspherical to ovoidal main body, composed of a smooth autophragm which is developed into a short, rounded apical horn. Three groups of ribbon-like processes arise from the autophragm in the apical, precingular/postcingular, and antapical series. The majorprocesses are mainly arcuate in section, and are linked distally by trabeculae, also of arcuate section, according to the arrangement described for the genus. The nature of the processes and trabeculae is variable. In smaller specimens, the length of the processes is approximately 1/4 of the main body diameter, and both processes and trabeculae are broad, giving the cyst a compact appearance (Plate 3, figs. 5-7). Larger specimens develop relatively longer processes, approximately one-half the main body diameter, and both processes and trabeculae are narrow, imparting a more expansive and open appearance to the cyst (Plate 3, figs. 1-4). Thread-like and tenuous subsidiary processes are inconsistently developed, most frequently in the area of the archeopyle. The antapical processes coalesce to form a conical horn that is closed at its tip. A free, single-plate, precingular archeopyle is developed. No operculum was observed.
Dimensions. Minimum (average) maximum: overall length 45(53)59 Ám, overall width 43(64)89 Ám; main body length 30(37)44 Ám, body width 27(37)47 Ám; apical horn length 3-4 Ám; apical crown length 7(11)14 Ám; antapical horn length 8(12)14 Ám; trabeculae width 2(3)5 Ám.