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Rhombodinium rugosum
Rhombodinium "rugosum" Michoux, 1988, p.30–31, pl.3, figs.1–9; text-figs.8A–B.
Holotype: Michoux, 1988, pl.3, figs.1–5; text-figs.8A–B.
NOW Petalodinium. Originally Rhombodinium, subsequently (and now) Petalodinium.
Age: early Eocene.
Original diagnosis: Michoux, 1988, p. 30
Circumcavate to cornucavate peridinioid cyst. Dorso-ventral compression moderate.
Paratabulation vaguely outlined by parasutural folds. Archeopyle intercalary (I/2a), trapezoidal. Operculum free. Endo- and perioperculum appressed.
Original description: Michoux, 1988, p.30
Peridinioid dinoflagellate cyst, rhomboidal to pentagonal in outline, with five horns. The apical and lateral horns are moderately to well developed. The left antapical horn is always well-developed; the right antapical horn shows variable degree of reduction. The endophragm is ellipsoidal to rhomboidal. Cavation is variable, with endo- and periphragm appressed over part of the ambitus of the cyst, separated elsewhere. Endophragm smooth, periphragm smooth to chagrinate. Paratabulation outlined by parasutural folds. Formula: 4", 3a, 7", Xc, 5""", 2"""". Periphragm ornamentation may include rare blunt processes at the base of the horns (see Plate 3, fig. 9). The archeopyle is of the W. meckelfeldensis type, with its anterior margin narrower than the posterior one, usually wider than high. The periarcheopyle is higher than the endoarcheopyle. The operculum is free, and both opercular pieces remain appressed (see Plate 3, figs. 5 and 8).
Dimensions. Pericyst. Length: 108 (115)135 µm. Width: 104 (115)122 µm. Holotype: 115 x 110 µm. Archeopyle. Length: 18 (22) 26 µm. Width: 28 (30) 33 µm. Holotype: 26 x 33 µm.
Affinities:
Michoux, 1988, p. 31: Rhombodinium rugosum differs from all previously described species of the genus by the development of parasutural folds completely outlining the paratabulation. Rhombodinium glabrum (Cookson) Vozzhennikova and R. translucidum have parasutural folds restricted to the paracingulum. R. rugosum is very similar to specimens illustrated by Goodman (1983, p. 384- 385, pl. 2, fig. 6-8) and informally named Rhombodinium "cingulatum." These specimens from Lower Eocene sediments of New Jersey differ from R. rugosum by even more conspicuous parasutural folds and more abundant processes.
Holotype: Michoux, 1988, pl.3, figs.1–5; text-figs.8A–B.
NOW Petalodinium. Originally Rhombodinium, subsequently (and now) Petalodinium.
Age: early Eocene.
Original diagnosis: Michoux, 1988, p. 30
Circumcavate to cornucavate peridinioid cyst. Dorso-ventral compression moderate.
Paratabulation vaguely outlined by parasutural folds. Archeopyle intercalary (I/2a), trapezoidal. Operculum free. Endo- and perioperculum appressed.
Original description: Michoux, 1988, p.30
Peridinioid dinoflagellate cyst, rhomboidal to pentagonal in outline, with five horns. The apical and lateral horns are moderately to well developed. The left antapical horn is always well-developed; the right antapical horn shows variable degree of reduction. The endophragm is ellipsoidal to rhomboidal. Cavation is variable, with endo- and periphragm appressed over part of the ambitus of the cyst, separated elsewhere. Endophragm smooth, periphragm smooth to chagrinate. Paratabulation outlined by parasutural folds. Formula: 4", 3a, 7", Xc, 5""", 2"""". Periphragm ornamentation may include rare blunt processes at the base of the horns (see Plate 3, fig. 9). The archeopyle is of the W. meckelfeldensis type, with its anterior margin narrower than the posterior one, usually wider than high. The periarcheopyle is higher than the endoarcheopyle. The operculum is free, and both opercular pieces remain appressed (see Plate 3, figs. 5 and 8).
Dimensions. Pericyst. Length: 108 (115)135 µm. Width: 104 (115)122 µm. Holotype: 115 x 110 µm. Archeopyle. Length: 18 (22) 26 µm. Width: 28 (30) 33 µm. Holotype: 26 x 33 µm.
Affinities:
Michoux, 1988, p. 31: Rhombodinium rugosum differs from all previously described species of the genus by the development of parasutural folds completely outlining the paratabulation. Rhombodinium glabrum (Cookson) Vozzhennikova and R. translucidum have parasutural folds restricted to the paracingulum. R. rugosum is very similar to specimens illustrated by Goodman (1983, p. 384- 385, pl. 2, fig. 6-8) and informally named Rhombodinium "cingulatum." These specimens from Lower Eocene sediments of New Jersey differ from R. rugosum by even more conspicuous parasutural folds and more abundant processes.