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Isabelidinium pellucidum
Isabelidinium pellucidum (Deflandre and Cookson, 1955) Lentin and Williams, 1977
Originally Deflandrea bakeri forma pellucida, subsequently Deflandrea pellucida, thirdly Isabelia pellucida (combination illegitimate), fourthly (and now) Isabelidinium pellucidum, fifthly Alterbia pellucida (combination illegitimate).
This taxon was raised to the species level by Cookson and Eisenack, 1958.
Yun, 1981, transferred this species to Alterbia Lentin and Williams, 1976. Lentin and Williams, 1985, retained it in Isabelidinium.
Holotype: Deflandre and Cookson, 1955, pl.4, fig.3
Locus typicus: Nelson bore, Victoria, Australia
Stratum typicum: Paleocene-Early Eocene
Original description: Deflandre and Cookson, 1955, p. 251: Deflandrea bakeri forma pellucida
Membrane of the theca thinner and more finely punctate than that of the type. Outline not especially enlarged in the region of the cyst. Posterior end simply and obliquely truncate, slightly depressed in the middle.
Dimensions: Type - theca, length 118 µm, breadth 77 µm; cyst, length 67 µm, breadth 74 µm. Other specimens: length up to 113 µm, breadth up to 92 µm.
Original description: Cookson and Eisenack, 1958, p. 27: Deflandrea pellucida
Theca elongate oval with convex sides that narrow anteriorly towards an acuminate apex and posteriorly towards an obliquely truncate or slightly concave antapex. A transverse girdle is either faintly indicated or absent, a somewhat polygonal aperture is present in the anterior portion of the epitheca.
The capsule, which is broader than long and flattened in the antero-posterior plane, invaribly extends laterally to the outer membrane. The membrane of the theca is finely granular, that of the capsule is smooth.
Dimensions: Type - theca 118 x 77 µm, capsule 67 x 74 µm. Western Australian examples - theca 109-128 x 76-81 µm, capsule 57-66 x 71-78 µm.
Originally Deflandrea bakeri forma pellucida, subsequently Deflandrea pellucida, thirdly Isabelia pellucida (combination illegitimate), fourthly (and now) Isabelidinium pellucidum, fifthly Alterbia pellucida (combination illegitimate).
This taxon was raised to the species level by Cookson and Eisenack, 1958.
Yun, 1981, transferred this species to Alterbia Lentin and Williams, 1976. Lentin and Williams, 1985, retained it in Isabelidinium.
Holotype: Deflandre and Cookson, 1955, pl.4, fig.3
Locus typicus: Nelson bore, Victoria, Australia
Stratum typicum: Paleocene-Early Eocene
Original description: Deflandre and Cookson, 1955, p. 251: Deflandrea bakeri forma pellucida
Membrane of the theca thinner and more finely punctate than that of the type. Outline not especially enlarged in the region of the cyst. Posterior end simply and obliquely truncate, slightly depressed in the middle.
Dimensions: Type - theca, length 118 µm, breadth 77 µm; cyst, length 67 µm, breadth 74 µm. Other specimens: length up to 113 µm, breadth up to 92 µm.
Original description: Cookson and Eisenack, 1958, p. 27: Deflandrea pellucida
Theca elongate oval with convex sides that narrow anteriorly towards an acuminate apex and posteriorly towards an obliquely truncate or slightly concave antapex. A transverse girdle is either faintly indicated or absent, a somewhat polygonal aperture is present in the anterior portion of the epitheca.
The capsule, which is broader than long and flattened in the antero-posterior plane, invaribly extends laterally to the outer membrane. The membrane of the theca is finely granular, that of the capsule is smooth.
Dimensions: Type - theca 118 x 77 µm, capsule 67 x 74 µm. Western Australian examples - theca 109-128 x 76-81 µm, capsule 57-66 x 71-78 µm.