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Trithyrodinium ioannidesii
Trithyrodinium ioannidesii Vieira and Mahdi, 2021
Holotype: Plate 7, figures 1 and 2, Vieira and Mahdi, 2021
Type locality. Møre Basin (Norway)
Stratigraphic extent. Late Cretaceous, ?middle Campanian
Original description: Vieira and Mahdi, 2021:
Diagnosis:
Peridinioid dinoflagellate cysts composed of two layers. The endophragm is relatively thick, bearing numerous non-tabular grana and coni of variable size even on a single specimen.
Description:
Peridiniacean, bicavate to circumcavate, rounded to subspherical dinoflagellate cysts, of intermediate size.
Archaeopyle: intercalary Type 3I, operculum often free.
Wall: Cyst consists of two layers; the endophragm is closely adpressed to the periphragm. The endophragm is relatively thick (up to 3 µm), covered with non-tabular grana and coni 2–7 µm in diameter and up to 5 µm in height. The periphragm is thin and hyaline, and the apical and antapical horns are not clearly visible. If present, it is very delicate, forming one short, broad-based and blunt apical and two antapical horns.
Dimensions:
Central body length 51 (57) 65 µm, width 51 (56) 64 µm
18 specimens measured
Affinities/Comparison:
Ioannides (1986, p. 40, pl. 20) recorded this species as Trithyrodinium sp. from the Santonian–Campanian (Sample C-60129) from Bylot Island (Arctic Canada), although it was never formally described. This species often possesses spherical to subspherical grana and coni of various sizes, and this diagnostic feature differentiates it from others within the genus. It differs from T. zakkii by having grana and coni rather than densely arranged solid, non-tabular spines.
Holotype: Plate 7, figures 1 and 2, Vieira and Mahdi, 2021
Type locality. Møre Basin (Norway)
Stratigraphic extent. Late Cretaceous, ?middle Campanian
Original description: Vieira and Mahdi, 2021:
Diagnosis:
Peridinioid dinoflagellate cysts composed of two layers. The endophragm is relatively thick, bearing numerous non-tabular grana and coni of variable size even on a single specimen.
Description:
Peridiniacean, bicavate to circumcavate, rounded to subspherical dinoflagellate cysts, of intermediate size.
Archaeopyle: intercalary Type 3I, operculum often free.
Wall: Cyst consists of two layers; the endophragm is closely adpressed to the periphragm. The endophragm is relatively thick (up to 3 µm), covered with non-tabular grana and coni 2–7 µm in diameter and up to 5 µm in height. The periphragm is thin and hyaline, and the apical and antapical horns are not clearly visible. If present, it is very delicate, forming one short, broad-based and blunt apical and two antapical horns.
Dimensions:
Central body length 51 (57) 65 µm, width 51 (56) 64 µm
18 specimens measured
Affinities/Comparison:
Ioannides (1986, p. 40, pl. 20) recorded this species as Trithyrodinium sp. from the Santonian–Campanian (Sample C-60129) from Bylot Island (Arctic Canada), although it was never formally described. This species often possesses spherical to subspherical grana and coni of various sizes, and this diagnostic feature differentiates it from others within the genus. It differs from T. zakkii by having grana and coni rather than densely arranged solid, non-tabular spines.