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Trithyrodinium fragile
Trithyrodinium fragile Davey, 1969
Taxonomic senior synonym: Trithyrodinium evittii, according to Nøhr-Hansen and Dam (1999, p.129).
Holotype: Davey, 1969, pl.3, fig.6
Locus typicus: Northern Natal,
Stratum typicum: Maastrichtian- Danian
Original diagnosis: Davey, 1969, p.11
Shell subspherical, consisting of a smooth brown inner body surrounded closely by a thin hyaline membrane which is produced into a small apical and two small antapical horns. The inner layer of the inner body is thin and colourless, the outer layer thick, brown and commonly possessing cresentic markings Cingulum and sulcus rarely discernible.
Holotype: inner body diameter 45 µm by 45 µm, length of apical horn 8 µm, length of antapical horns 4 µm and 6 µm. Range: inner body diameter 41(48.5)58 µm. Number of specimens measured, 12.
Original desctiption: Davey, 1969, p.11
The outer membrane is extremely delicate and only occasionally are the apical and antapical horns discernible. Because of the fine nature of this membrane an archaeopyle has not been observed. The subspherical inner body typically possesses a network of curved areas devoid of the brown outer layer (pl.3, fig.9). It appears unlikely that curved portions of this layer have been lost but rather that at some stage the inner body has expanded and that the brown outer layer, being somewhat brittle, developed cresentic cracks. A large angular opening is developed on the dorsal epitractal surface of the inner body by the loss of three plate-areas. The shape and position of the latter indicate that they are anterior intercalary in position. The ventral surface is intact and on one specimen bears sulcal and also cingular depressions. The apical region of the inner body remains as an angular projection, or lingula, over the opening.
Affinities:
Davey, 1969, p.11: T. fragile is a distinctive species and appears to be most closely related to T. suspecta (Manum and Cookson, 1964). The latter, however, possesses a thick granular inner body wall. Unfortunately, since the outer membrane is commonly lost, T.fragile may be misidentified as a leiosphere-like dinoflagellate cyst possessing a large angular archaeopyle. However, the characteristic sculpture of the inner body will mitigate against this.
Taxonomic senior synonym: Trithyrodinium evittii, according to Nøhr-Hansen and Dam (1999, p.129).
Holotype: Davey, 1969, pl.3, fig.6
Locus typicus: Northern Natal,
Stratum typicum: Maastrichtian- Danian
Original diagnosis: Davey, 1969, p.11
Shell subspherical, consisting of a smooth brown inner body surrounded closely by a thin hyaline membrane which is produced into a small apical and two small antapical horns. The inner layer of the inner body is thin and colourless, the outer layer thick, brown and commonly possessing cresentic markings Cingulum and sulcus rarely discernible.
Holotype: inner body diameter 45 µm by 45 µm, length of apical horn 8 µm, length of antapical horns 4 µm and 6 µm. Range: inner body diameter 41(48.5)58 µm. Number of specimens measured, 12.
Original desctiption: Davey, 1969, p.11
The outer membrane is extremely delicate and only occasionally are the apical and antapical horns discernible. Because of the fine nature of this membrane an archaeopyle has not been observed. The subspherical inner body typically possesses a network of curved areas devoid of the brown outer layer (pl.3, fig.9). It appears unlikely that curved portions of this layer have been lost but rather that at some stage the inner body has expanded and that the brown outer layer, being somewhat brittle, developed cresentic cracks. A large angular opening is developed on the dorsal epitractal surface of the inner body by the loss of three plate-areas. The shape and position of the latter indicate that they are anterior intercalary in position. The ventral surface is intact and on one specimen bears sulcal and also cingular depressions. The apical region of the inner body remains as an angular projection, or lingula, over the opening.
Affinities:
Davey, 1969, p.11: T. fragile is a distinctive species and appears to be most closely related to T. suspecta (Manum and Cookson, 1964). The latter, however, possesses a thick granular inner body wall. Unfortunately, since the outer membrane is commonly lost, T.fragile may be misidentified as a leiosphere-like dinoflagellate cyst possessing a large angular archaeopyle. However, the characteristic sculpture of the inner body will mitigate against this.