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Gerdiocysta
From Williams et al., 2017:
[Gerdiocysta, Liengjarern et al., 1980, p. 482
Type species: Gerdiocysta conopeum, Liengjarern et al., 1980 (pl.53, fig.2)]
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Original description: [Liengjarern et al., 1980]:
Description:
Cyst ambitus subcircular, posteriorly bilobed or rounded; dorso-ventral compression moderate to strong. Pericyst bearing solid penitabular to intratabular processes arranged into annular, soleate, or linear complexes. The process complexes support a reticulate or membraneous ectophragm, which on the dorsal face and laterally simulate the outline of the paraplates. On the ventral face, a median area of variable size is free of ornament and ectophragm.
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Modified description:
Stover and Williams 1987, p. 103:
Synopsis:
Cysts proximate, lenticular; body with intratabular to penitabular process complexes which support a discontinuous ectophragm that extends over most of the cyst; paratabulation gonyaulacacean, inferred formula: 4`, 6", 6c, 5```, 1````, and 1ps; archeopyle apical, type [4A].
Description:
Shape: Body lenticular; antapical margin may be bilobate.
Wall relationships: Endophragm and periphragm appressed; process complexes support a discontinuous ectophragm which covers most of
the cyst. Ectophragm may extend across several process complexes, or be absent over areas between process complexes.
Wall features: Pericyst bears annular, soleate, or linear intratabular to penitabular process complexes. Periphragm between processes ornamented with features of low relief.
Archeopyle: Apical, type [4A], archeopyle margin zigzag; operculum free; sulcal notch offset.
Paratabulation: Indicated by process complexes and archeopyle; gonyaulacacean, process formula: 4`, 6", 6c, 5```, 1````, and 1ps.
Paracingulum: Indicated by linear process complex, or by low parallel, transverse ridges on the dorsal surface. Ventral expression of paracingulum often indistinct.
Parasulcus: Expressed by midventral area which is free of processes and ectophragm.
Size: Intermediate to large; width about 70 to 105 µm, including processes.
Affinities:
Gerdiocysta differs from Areoligera Lejeune Carpentier 1938 emended Williams and Downie in Davey et al. 1966 in possessing an ectophragm; it differs from Riculacysta Stover 1977 in having process complexes and in particular, a large middorsal process complex. Glaphyrocysta Stover and Evitt 1978 has a trabecular ectophragm.
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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.
Gerdiocysta Liengjarern et al., 1980. Stover and Williams (1987, p.101) provided the following synopsis. Cysts proximate, lenticular; body with intratabular to penitabular process complexes, which support a discontinuous ectophragm that extends over most of the cyst; paratabulation gonyaulacacvean, inferred formula 4`, 6", 6c, 5"', 1"'', 1ps; archeopyle apical, type (4A).
[Gerdiocysta, Liengjarern et al., 1980, p. 482
Type species: Gerdiocysta conopeum, Liengjarern et al., 1980 (pl.53, fig.2)]
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Original description: [Liengjarern et al., 1980]:
Description:
Cyst ambitus subcircular, posteriorly bilobed or rounded; dorso-ventral compression moderate to strong. Pericyst bearing solid penitabular to intratabular processes arranged into annular, soleate, or linear complexes. The process complexes support a reticulate or membraneous ectophragm, which on the dorsal face and laterally simulate the outline of the paraplates. On the ventral face, a median area of variable size is free of ornament and ectophragm.
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Modified description:
Stover and Williams 1987, p. 103:
Synopsis:
Cysts proximate, lenticular; body with intratabular to penitabular process complexes which support a discontinuous ectophragm that extends over most of the cyst; paratabulation gonyaulacacean, inferred formula: 4`, 6", 6c, 5```, 1````, and 1ps; archeopyle apical, type [4A].
Description:
Shape: Body lenticular; antapical margin may be bilobate.
Wall relationships: Endophragm and periphragm appressed; process complexes support a discontinuous ectophragm which covers most of
the cyst. Ectophragm may extend across several process complexes, or be absent over areas between process complexes.
Wall features: Pericyst bears annular, soleate, or linear intratabular to penitabular process complexes. Periphragm between processes ornamented with features of low relief.
Archeopyle: Apical, type [4A], archeopyle margin zigzag; operculum free; sulcal notch offset.
Paratabulation: Indicated by process complexes and archeopyle; gonyaulacacean, process formula: 4`, 6", 6c, 5```, 1````, and 1ps.
Paracingulum: Indicated by linear process complex, or by low parallel, transverse ridges on the dorsal surface. Ventral expression of paracingulum often indistinct.
Parasulcus: Expressed by midventral area which is free of processes and ectophragm.
Size: Intermediate to large; width about 70 to 105 µm, including processes.
Affinities:
Gerdiocysta differs from Areoligera Lejeune Carpentier 1938 emended Williams and Downie in Davey et al. 1966 in possessing an ectophragm; it differs from Riculacysta Stover 1977 in having process complexes and in particular, a large middorsal process complex. Glaphyrocysta Stover and Evitt 1978 has a trabecular ectophragm.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Gerdiocysta Liengjarern et al., 1980. Stover and Williams (1987, p.101) provided the following synopsis. Cysts proximate, lenticular; body with intratabular to penitabular process complexes, which support a discontinuous ectophragm that extends over most of the cyst; paratabulation gonyaulacacvean, inferred formula 4`, 6", 6c, 5"', 1"'', 1ps; archeopyle apical, type (4A).