Back
Impagidinium ovum
From Fensome et al., 2019:
Impagidinium ?ovum (Sah et al., 1970, p.147–148, pl.2, fig.25) Stover and Evitt, 1978, p.166. Holotype: Sah et al., 1970, pl.2, fig.25. Originally Leptodinium, subsequently (and now) Impagidinium?. Questionable assignment: Stover and Evitt (1978, p.166). NIA. Age: Late Cretaceous.
---------------------------------------------------------------------------------------------------
Original description: [Sah et al., 1970]:
Leptodinium ovum sp. nov.
PI. 2, Fig. 25
Holotype - PI. 2, Fig. 25. Size 60 x 51 μ. Slide no. 3649.
No. of specimens studied- 12.
Diagnosis - Cysts oval, with simple precingular archeopyle; equatorial girdle distinct, sutures raised, protruding at the margin, occasionally ledged; cyst membrane up to 1p.thick, surface ± laevigate or finely sculptured with grana or coni, folds generally present.
Description - Cysts mostly oval with equally broad rounded ends, sometimes subcircular, 50-70 x 39-66 μ. Archeopyle not seen in most specimens perhaps due to folding and crumpled susceptibility of cyst membrane. Ledge while discernible not more than 4 μ broad. Sutures well developed, straight, demarcating plate. Epitract and hypotract equal in size. Grana or coni less than 1 p.in height, closely placed and evenly distributed.
Comparison - Leptodinium membranigerum Gerl. (1961) and Leptodinium cf. L. membranigerum Drugg (1967) resemble the present species in shape and size but the two former types differ in having considerably thicker cyst membrane (up to 4 μ) and well developed ledge.
Impagidinium ?ovum (Sah et al., 1970, p.147–148, pl.2, fig.25) Stover and Evitt, 1978, p.166. Holotype: Sah et al., 1970, pl.2, fig.25. Originally Leptodinium, subsequently (and now) Impagidinium?. Questionable assignment: Stover and Evitt (1978, p.166). NIA. Age: Late Cretaceous.
---------------------------------------------------------------------------------------------------
Original description: [Sah et al., 1970]:
Leptodinium ovum sp. nov.
PI. 2, Fig. 25
Holotype - PI. 2, Fig. 25. Size 60 x 51 μ. Slide no. 3649.
No. of specimens studied- 12.
Diagnosis - Cysts oval, with simple precingular archeopyle; equatorial girdle distinct, sutures raised, protruding at the margin, occasionally ledged; cyst membrane up to 1p.thick, surface ± laevigate or finely sculptured with grana or coni, folds generally present.
Description - Cysts mostly oval with equally broad rounded ends, sometimes subcircular, 50-70 x 39-66 μ. Archeopyle not seen in most specimens perhaps due to folding and crumpled susceptibility of cyst membrane. Ledge while discernible not more than 4 μ broad. Sutures well developed, straight, demarcating plate. Epitract and hypotract equal in size. Grana or coni less than 1 p.in height, closely placed and evenly distributed.
Comparison - Leptodinium membranigerum Gerl. (1961) and Leptodinium cf. L. membranigerum Drugg (1967) resemble the present species in shape and size but the two former types differ in having considerably thicker cyst membrane (up to 4 μ) and well developed ledge.