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Leptodinium antigonium
Leptodinium? antigonium Ioannoides et al., 1977
Originally Leptodinium, subsequently (and now) Leptodinium?. Stover and Evitt, 1978, considered this to be a provisionally accepted species of Leptodinium.
Holotype: Ioannoides et al., 1977, pl.3, fig.8; Jan du Chêne et al., 1986, pl.74, figs.7-8
Locus typicus: Clavell"s Hard, Dorset, England
Stratum typicum: Kimmeridgian
Original diagnosis: Ioannoides et al., 1977, p. 456
Theca ovoidal to polyhedral divided by spiral cingulum into epitract and hypotract of equal size.Tabulation 4", 6"", ?6c, 5""", 1p, 1"""". Plate boundaries demarcated by high denticulate to spinous, occasionally irregularly perforated membranous crests. In parts, denticulation is so deep that outer edge appears tuberculate. Sulcus broad with only small epitract portion. Shell surface smooth, archaeopyle precingular, typically developed by loss of plate 3"".
Original description: Ioannoides et al., 1977, p. 456
Cyst wall relatively thin and always folded. Anterior prolongation of sulcus entirely occupied by enlarged plate 1". Plate 3""" is largest of postcingular plates, whereas plate 1""" is reduced in size, triangular in shape, and larger than the somewhat circular posterior intercalary plate. A polygonal plate occupies the antapex. Periphragm and crests smooth. Multiple secondary folds present.
Dimensions: Range: overall length 50-94 Ám, breadth 47-85 Ám; sutural crests up to 4.5 Ám high (30 specimens measured) .
Affinities:
loannides et al., 1977, p. 457: The multiple folds precluded an accurate definition of the cingular plates. Leptodinium antigonium loannides, Stavrinos, and Downie, is distinguished by its shape and nature of crests.
Originally Leptodinium, subsequently (and now) Leptodinium?. Stover and Evitt, 1978, considered this to be a provisionally accepted species of Leptodinium.
Holotype: Ioannoides et al., 1977, pl.3, fig.8; Jan du Chêne et al., 1986, pl.74, figs.7-8
Locus typicus: Clavell"s Hard, Dorset, England
Stratum typicum: Kimmeridgian
Original diagnosis: Ioannoides et al., 1977, p. 456
Theca ovoidal to polyhedral divided by spiral cingulum into epitract and hypotract of equal size.Tabulation 4", 6"", ?6c, 5""", 1p, 1"""". Plate boundaries demarcated by high denticulate to spinous, occasionally irregularly perforated membranous crests. In parts, denticulation is so deep that outer edge appears tuberculate. Sulcus broad with only small epitract portion. Shell surface smooth, archaeopyle precingular, typically developed by loss of plate 3"".
Original description: Ioannoides et al., 1977, p. 456
Cyst wall relatively thin and always folded. Anterior prolongation of sulcus entirely occupied by enlarged plate 1". Plate 3""" is largest of postcingular plates, whereas plate 1""" is reduced in size, triangular in shape, and larger than the somewhat circular posterior intercalary plate. A polygonal plate occupies the antapex. Periphragm and crests smooth. Multiple secondary folds present.
Dimensions: Range: overall length 50-94 Ám, breadth 47-85 Ám; sutural crests up to 4.5 Ám high (30 specimens measured) .
Affinities:
loannides et al., 1977, p. 457: The multiple folds precluded an accurate definition of the cingular plates. Leptodinium antigonium loannides, Stavrinos, and Downie, is distinguished by its shape and nature of crests.