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Kylindrocysta
From Williams et al., 2017:
[Kylindrocysta, Fenton et al. 1980, p. 162
Type species: Kylindrocysta spinosa, Fenton et al., 1980 (pl.14, fig.13)]
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Original description: [Fenton et al., 1980]:
Description:
Proximate cyst, cylindrical, strongly elongate to subquadrate in outline. Paratabulation absent or indistinct. Paracingulum and parasulcus apparently absent. Apex flattened or convex, composed of five paraplates, bulk of cyst composed of five elongate paraplates; with a flat to convex pentagonal antapical paraplate. Cyst wall complex, consisting of thin endophragm and spongy, fibrous periphragm, closely appressed. Cyst surface spinose to granulose. Paratabulation formula: 5`, ?5", ?5```,1````.
Archaeopyle formed by loss of two or more apical paraplates.
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Modified description:
Stover and Williams, 1987, p. 137:
Synopsis:
Cysts proximate, elongate with a subquadrate outline, without horns; uniformly ornamented with features of low relief; paratabulation indicated mainly by archeopyle, less so by accessory sutures and very faint parasutural features, formula: 5`, ?5", ?5```, 1````. Archeopyle apical, types 2A-5A, opercular pieces free.
Description:
Shape: Proximate, elongate, outline subquadrate.
Wall relationships: Undifferentiated autophragm under normal light microscopy. SEM studies reveal appressed endophragm and periphragm.
Wall features: Faint parasutural features may be discernible. Surface ornamented uniformly with features of low relief.
Archeopyle: Apical, types 2A-5A; operculum composed of two, dorsally? inclined paraplates normally involved in archeopyle formation and three smaller ventral(?) paraplates, which may or may not be involved in archeopyle formation.
Paratabulation: Indicated mainly by archeopyle, much less so by vague parasutural features and occasionally by accessory archeopyle sutures;
formula reported as 5`, ?5", ?5```, 1````.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Small to intermediate, length about 30 to 55 µm.
Affinities:
Kylindrocysta differs from Pyxidiella Cookson and Eisenack 1958 in having two to five supposedly apical paraplates involved in archeopyle formation instead of a single, intercalary paraplate. Comparodinium Morbey 1975 emended Wille and Gocht 1979 has an archeopyle formed by the release of two dorsal apical paraplates (3` and 4`), hence, it may prove difficult to separate specimens of Comparodinium from those of Kylindrocysta with 2A archeopyles.
[Kylindrocysta, Fenton et al. 1980, p. 162
Type species: Kylindrocysta spinosa, Fenton et al., 1980 (pl.14, fig.13)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Fenton et al., 1980]:
Description:
Proximate cyst, cylindrical, strongly elongate to subquadrate in outline. Paratabulation absent or indistinct. Paracingulum and parasulcus apparently absent. Apex flattened or convex, composed of five paraplates, bulk of cyst composed of five elongate paraplates; with a flat to convex pentagonal antapical paraplate. Cyst wall complex, consisting of thin endophragm and spongy, fibrous periphragm, closely appressed. Cyst surface spinose to granulose. Paratabulation formula: 5`, ?5", ?5```,1````.
Archaeopyle formed by loss of two or more apical paraplates.
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Modified description:
Stover and Williams, 1987, p. 137:
Synopsis:
Cysts proximate, elongate with a subquadrate outline, without horns; uniformly ornamented with features of low relief; paratabulation indicated mainly by archeopyle, less so by accessory sutures and very faint parasutural features, formula: 5`, ?5", ?5```, 1````. Archeopyle apical, types 2A-5A, opercular pieces free.
Description:
Shape: Proximate, elongate, outline subquadrate.
Wall relationships: Undifferentiated autophragm under normal light microscopy. SEM studies reveal appressed endophragm and periphragm.
Wall features: Faint parasutural features may be discernible. Surface ornamented uniformly with features of low relief.
Archeopyle: Apical, types 2A-5A; operculum composed of two, dorsally? inclined paraplates normally involved in archeopyle formation and three smaller ventral(?) paraplates, which may or may not be involved in archeopyle formation.
Paratabulation: Indicated mainly by archeopyle, much less so by vague parasutural features and occasionally by accessory archeopyle sutures;
formula reported as 5`, ?5", ?5```, 1````.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Small to intermediate, length about 30 to 55 µm.
Affinities:
Kylindrocysta differs from Pyxidiella Cookson and Eisenack 1958 in having two to five supposedly apical paraplates involved in archeopyle formation instead of a single, intercalary paraplate. Comparodinium Morbey 1975 emended Wille and Gocht 1979 has an archeopyle formed by the release of two dorsal apical paraplates (3` and 4`), hence, it may prove difficult to separate specimens of Comparodinium from those of Kylindrocysta with 2A archeopyles.