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Operculodinium
From Williams et al., 2017:
[Operculodinium, Wall, 1967, p. 110-111; Emendation: Matsuoka et al., 1997, p.22.
Type species: originally as Hystrichosphaeridium centrocarpum, Deflandre and Cookson, 1955 (pl.8, figs.3–4)] ; Operculodinium centrocarpum, Wall, 1967
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Original description: [Wall, 1967]:
Diagnosis:
Spherical to ovoid cyst possessing simple, dorsal precingular archaeopyles (reflecting plate 3``), and lacking polar structures. A weakly defined girdle and ventral sulcal depression often present. Cell wall double, the inner thin and the outer thicker and microgranular or microreticulate. Elements of ornamentation variable, from small cones to long spines but all with circular, minutely striated bases and often capitate extremities. Spine arrangement intratabular with several spines to each plate-area, commonly arranged immediately within the reflected plate-area margins.
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Modified description:
Stover and Evitt 1978, p. 178-179:
Synopsis:
Cysts proximochorate to skolochorate; body subspherical to ellipsoidal with numerous nontabular cones, spines, or processes of similar size and shape, which are typically capitate, hollow, and closed distally or solid; archeopyle precingular, Type P.
Description:
Shape: Body subspherical to ellipsoidal.
Wall relationships: Endophragm and periphragm appressed between projections.
Wall features: No parasutural features. Surface of body reveals nontabular cones, spines, and processes of similar size and shape, which are typically capitate, hollow, and closed distally or solid; areas between projections granulate, punctoreticulate to finely rugulate.
Paratabulation: Expressed generally by archeopyle only; other indications less distinct and usually inconsistent.
Archeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Not indicated, or expressed by faint transverse alignment of projections.
Parasulcus: Generally not indicated.
Size: Small to large.
Affinities:
Operculodinium differs from Exochosphaeridium and Amphorosphaeridium in not having fibrous processes and lacking differentiated apical and/or antapical processes. It differs from Lingulodinium in having a precingular archeopyle formed by the release of paraplate 3``, only and in having capitate processes. Operculodinium differs from Cleistosphaeridium in having a precingular rather than an apical archeopyle.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Operculodinium Wall, 1967, emend. Matsuoka et al., 1997. As revised by Matsuoka et al. (1997), Spherical to ovoid cysts possessing a 3" precingular archeopyle and lacking polar structures. A weakly defined girdle and ventral sulcal depression may or may not be present. Cyst wall composed of a thin, smooth endophragm and a thicker microgranular or microreticulate endophragm. Positive sculpturing varies from small cones to long processes with circular bases. Process bases may be striate or microreticulate. A variety of distal process shaft terminations may be present, including capitate, recurved, truncated or patulate, though usually one type per specimen. Process distribution nontabular and/or intratabular, with several processes per paraplate area. These authors emended the genus to include nontabular processes and a wider variety of process terminations than was included in the original generic diagnosis.
[Operculodinium, Wall, 1967, p. 110-111; Emendation: Matsuoka et al., 1997, p.22.
Type species: originally as Hystrichosphaeridium centrocarpum, Deflandre and Cookson, 1955 (pl.8, figs.3–4)] ; Operculodinium centrocarpum, Wall, 1967
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Wall, 1967]:
Diagnosis:
Spherical to ovoid cyst possessing simple, dorsal precingular archaeopyles (reflecting plate 3``), and lacking polar structures. A weakly defined girdle and ventral sulcal depression often present. Cell wall double, the inner thin and the outer thicker and microgranular or microreticulate. Elements of ornamentation variable, from small cones to long spines but all with circular, minutely striated bases and often capitate extremities. Spine arrangement intratabular with several spines to each plate-area, commonly arranged immediately within the reflected plate-area margins.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt 1978, p. 178-179:
Synopsis:
Cysts proximochorate to skolochorate; body subspherical to ellipsoidal with numerous nontabular cones, spines, or processes of similar size and shape, which are typically capitate, hollow, and closed distally or solid; archeopyle precingular, Type P.
Description:
Shape: Body subspherical to ellipsoidal.
Wall relationships: Endophragm and periphragm appressed between projections.
Wall features: No parasutural features. Surface of body reveals nontabular cones, spines, and processes of similar size and shape, which are typically capitate, hollow, and closed distally or solid; areas between projections granulate, punctoreticulate to finely rugulate.
Paratabulation: Expressed generally by archeopyle only; other indications less distinct and usually inconsistent.
Archeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Not indicated, or expressed by faint transverse alignment of projections.
Parasulcus: Generally not indicated.
Size: Small to large.
Affinities:
Operculodinium differs from Exochosphaeridium and Amphorosphaeridium in not having fibrous processes and lacking differentiated apical and/or antapical processes. It differs from Lingulodinium in having a precingular archeopyle formed by the release of paraplate 3``, only and in having capitate processes. Operculodinium differs from Cleistosphaeridium in having a precingular rather than an apical archeopyle.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Operculodinium Wall, 1967, emend. Matsuoka et al., 1997. As revised by Matsuoka et al. (1997), Spherical to ovoid cysts possessing a 3" precingular archeopyle and lacking polar structures. A weakly defined girdle and ventral sulcal depression may or may not be present. Cyst wall composed of a thin, smooth endophragm and a thicker microgranular or microreticulate endophragm. Positive sculpturing varies from small cones to long processes with circular bases. Process bases may be striate or microreticulate. A variety of distal process shaft terminations may be present, including capitate, recurved, truncated or patulate, though usually one type per specimen. Process distribution nontabular and/or intratabular, with several processes per paraplate area. These authors emended the genus to include nontabular processes and a wider variety of process terminations than was included in the original generic diagnosis.