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Rhombodinium ornatum
Rhombodinium ornatum (Vozzhennikova, 1967, p.103–104, pl.42, figs.1–3; pl.43, figs.1–4; pl.44, figs.1–12; pl.45, figs.1–3) Williams et al., 2015, p.311. Emendations: Lentin and Vozzhennikova, 1989, p.223; Vasilyeva in Andreeva-Grigorovich et al., 2011, p.53.
Originally Kisselevia, subsequently (and now) Rhombodinium.
Holotype: Vozzhennikova, 1967, pl.44, fig.6, lost according to Lentin and Vozzhennikova (1989, p.223).
Lectotype: Vozzhennikova, 1967, pl.44, fig.1 (as holotype of Kisselevia ornata forma reticulata); Lentin and Vozzhennikova, 1989, pl.1, figs.1–2; Lentin and Vozzhennikova, 1990, pl.9, fig.1; designated by Lentin and Vozzhennikova (1989, p.223).
Age: Eocene.
Original description: Vozzhennikova (1960) 1967, p. 103-104
Theca divided by the transverse furrow into two almost equal parts. Epitheca triangular with a small apical outgrowth. Hypotheca trapeziform with a short, acutely pointed antapical horn. Lateral angles slightly drawn out, or not drawn out. Thecal sculpture reticulate or reticulate spinous. Thecal armour divided into plates (fields) by colored sutures, which permit some recognition of the shape and position of the plates but do not allow an exact assessment of their number. The plate formula is suggested tentatively as: on the epitheca, na + 3cp + (5 6) np; on the hypotheca, (5?) zd + 2cp' + na'. The pylome takes the place of the middle intermediate plate. Transverse furrow equatorial and approximately annulate although its ends are separated from each other by a short distance. The central field occurs on the hypotheca but does not extend to the antapex. It corresponds with the position of the longitudinal furrow. Pylome trapeziform.
Emended diagnosis: Lentin and Vozzhennikova, 1989, p. 223
Outline roundly pentagonal with two short antapical horns, of which the right is slightly reduced. The endophragm is thin and similar in outline to the periphragm. Periphragm very thin, ornamented with a delicate reticulum which may be reduced over the narrow pandasutural areas, particularly on the hypocyst. The reticulum is absent or very reduced on paraplates 2', 4', 2" and 6". Low, very delicate pore-like elements are present at the angles where the reticular elements join. The reticulum may be more strongly developed along the paraplate margins. The archeopyle is formed by the loss of the quadra 2a paraplate. The operculum is free or remains attached.
Size: Lectotype: length 103 µm, width 96 µm. Range: length 99-103 µm, width 94-120 µm.
Originally Kisselevia, subsequently (and now) Rhombodinium.
Holotype: Vozzhennikova, 1967, pl.44, fig.6, lost according to Lentin and Vozzhennikova (1989, p.223).
Lectotype: Vozzhennikova, 1967, pl.44, fig.1 (as holotype of Kisselevia ornata forma reticulata); Lentin and Vozzhennikova, 1989, pl.1, figs.1–2; Lentin and Vozzhennikova, 1990, pl.9, fig.1; designated by Lentin and Vozzhennikova (1989, p.223).
Age: Eocene.
Original description: Vozzhennikova (1960) 1967, p. 103-104
Theca divided by the transverse furrow into two almost equal parts. Epitheca triangular with a small apical outgrowth. Hypotheca trapeziform with a short, acutely pointed antapical horn. Lateral angles slightly drawn out, or not drawn out. Thecal sculpture reticulate or reticulate spinous. Thecal armour divided into plates (fields) by colored sutures, which permit some recognition of the shape and position of the plates but do not allow an exact assessment of their number. The plate formula is suggested tentatively as: on the epitheca, na + 3cp + (5 6) np; on the hypotheca, (5?) zd + 2cp' + na'. The pylome takes the place of the middle intermediate plate. Transverse furrow equatorial and approximately annulate although its ends are separated from each other by a short distance. The central field occurs on the hypotheca but does not extend to the antapex. It corresponds with the position of the longitudinal furrow. Pylome trapeziform.
Emended diagnosis: Lentin and Vozzhennikova, 1989, p. 223
Outline roundly pentagonal with two short antapical horns, of which the right is slightly reduced. The endophragm is thin and similar in outline to the periphragm. Periphragm very thin, ornamented with a delicate reticulum which may be reduced over the narrow pandasutural areas, particularly on the hypocyst. The reticulum is absent or very reduced on paraplates 2', 4', 2" and 6". Low, very delicate pore-like elements are present at the angles where the reticular elements join. The reticulum may be more strongly developed along the paraplate margins. The archeopyle is formed by the loss of the quadra 2a paraplate. The operculum is free or remains attached.
Size: Lectotype: length 103 µm, width 96 µm. Range: length 99-103 µm, width 94-120 µm.