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Hebecysta
From Williams et al., 2017:
[Hebecysta, Bujak and Fisher, 1976, p. 64
Type species: Hebecysta brevicornuta, Bujak and Fisher, 1976 ( pl.9, fig.11)]
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Original description: [Bujak and Fisher, 1976]: (Translation: LPP):
Description:
Double-walled dinoflagellate cyst with subpolygonal, subrhomboidal, ovoidal or spherical endophragm.
Periphragm in contact with endophragm except where periphragm forms low crests along cingular borders and occasional tubular crests on epitract. Small, distinct apical horn also often formed by separation of two walls.
Archeopyle formed by displacement of up to three anterior intercalary plates.
Affinities:
The genus Hebecysta differs from Sverdrupiella in possessing an endophragm and periphragm which are mostly in contact, from Heibergella in being double-walled and from Noricysta in forming an intercalary archaeopyle. Tabular sutures near the apex of Hebecysta indicate the presence of four apical plates and at least three intercalary plates.
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Modified description:
Stover and Evit, 1978, p. 106:
Synopsis:
Cysts proximate, locally cavate, subspherical to ellipsoidal, with short apical horn and no antapical horns; endophragm and periphragm appressed except at bases of horn and low paracingular crests; archeopyle intercalary, Types 2I or 3I.
Description:
Shape: Subspherical to ellipsoidal with short apical horn only.
Wall relationships: Cysts locally cavate; endophragm and periphragm appressed, except at bases of the apical horn and paracingular crests.
Wall features: No parasutural features except for occasional parasutural (?) crests on epiperiphragm near the apex; periphragm smooth or granular.
Paratabulation: Generally indicated by archeopyle and paracingulum, occasionally also by faint parasutural(?) features near apex where four apical paraplates may be indicated.
Archeopyle: Intercalary, Types 2I or 3I; opercular pieces apparently free or adherent.
Paracingulum: Indicated by low, transverse, parallel equatorial crests.
Parasulcus: Not indicated.
Size: Intermediate.
Affinities:
Hebecysta differs from Pareodinia, which also possesses an apical horn and a 2I or 3I archeopyle, in being locally cavate and in having a more clearly delimited paracingulum.
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Extended description:
Below, 1987, p. 126:
Diagnosis:
Vesicle/plate arrangement of dinoflagellate amphiesma cop, pop, cap, 5`, 3a, 7``, nc, n```, n````, ns. Cysts proximate, proximochorate, cavate, acavate, spheroidal, ovoidal, ovaloidal, biconical, peridinoidal, of variable size. Wall consisting of pedium and luxuria. Surface smooth, ornamented, nonareate, areate. Areation formula NR PR/XPR, NR`/5`, NRa/3a, NR``/7``, NRc/Xc, NR```/n```, NR````/n````, NRs/Xns. Archaeopyle anterior intercalary, 1a+2a+3a, operculum solvate, secate, general opercular formula 1a(s)+2a(s)+3a(s).
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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.
Hebecysta Bujak and Fisher, 1976. Below (1987a) gave the following expanded description. Arrangement of vesicles on the dinoflagellate amphiesma cop, pop, cap, 5`, 3a, 7", nc, n''', n'''', ns. Cyst proximate, proximochorate, cavate, acavate, spheroidal, ovoidal, ovaloidal, biconical, peridinioidal, of varying size. Wall composed of pedium and luxuria; surface glabrous, ornamented, nonareate, areate. ... Archeopyle anterior intercalary, 1a = 2a = 3a; operculum solvate, secate, general opercular formula 1a + 2a + 3a. Hebecysta differs from Heibergella in being two-walled.
[Hebecysta, Bujak and Fisher, 1976, p. 64
Type species: Hebecysta brevicornuta, Bujak and Fisher, 1976 ( pl.9, fig.11)]
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Original description: [Bujak and Fisher, 1976]: (Translation: LPP):
Description:
Double-walled dinoflagellate cyst with subpolygonal, subrhomboidal, ovoidal or spherical endophragm.
Periphragm in contact with endophragm except where periphragm forms low crests along cingular borders and occasional tubular crests on epitract. Small, distinct apical horn also often formed by separation of two walls.
Archeopyle formed by displacement of up to three anterior intercalary plates.
Affinities:
The genus Hebecysta differs from Sverdrupiella in possessing an endophragm and periphragm which are mostly in contact, from Heibergella in being double-walled and from Noricysta in forming an intercalary archaeopyle. Tabular sutures near the apex of Hebecysta indicate the presence of four apical plates and at least three intercalary plates.
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Modified description:
Stover and Evit, 1978, p. 106:
Synopsis:
Cysts proximate, locally cavate, subspherical to ellipsoidal, with short apical horn and no antapical horns; endophragm and periphragm appressed except at bases of horn and low paracingular crests; archeopyle intercalary, Types 2I or 3I.
Description:
Shape: Subspherical to ellipsoidal with short apical horn only.
Wall relationships: Cysts locally cavate; endophragm and periphragm appressed, except at bases of the apical horn and paracingular crests.
Wall features: No parasutural features except for occasional parasutural (?) crests on epiperiphragm near the apex; periphragm smooth or granular.
Paratabulation: Generally indicated by archeopyle and paracingulum, occasionally also by faint parasutural(?) features near apex where four apical paraplates may be indicated.
Archeopyle: Intercalary, Types 2I or 3I; opercular pieces apparently free or adherent.
Paracingulum: Indicated by low, transverse, parallel equatorial crests.
Parasulcus: Not indicated.
Size: Intermediate.
Affinities:
Hebecysta differs from Pareodinia, which also possesses an apical horn and a 2I or 3I archeopyle, in being locally cavate and in having a more clearly delimited paracingulum.
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Extended description:
Below, 1987, p. 126:
Diagnosis:
Vesicle/plate arrangement of dinoflagellate amphiesma cop, pop, cap, 5`, 3a, 7``, nc, n```, n````, ns. Cysts proximate, proximochorate, cavate, acavate, spheroidal, ovoidal, ovaloidal, biconical, peridinoidal, of variable size. Wall consisting of pedium and luxuria. Surface smooth, ornamented, nonareate, areate. Areation formula NR PR/XPR, NR`/5`, NRa/3a, NR``/7``, NRc/Xc, NR```/n```, NR````/n````, NRs/Xns. Archaeopyle anterior intercalary, 1a+2a+3a, operculum solvate, secate, general opercular formula 1a(s)+2a(s)+3a(s).
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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.
Hebecysta Bujak and Fisher, 1976. Below (1987a) gave the following expanded description. Arrangement of vesicles on the dinoflagellate amphiesma cop, pop, cap, 5`, 3a, 7", nc, n''', n'''', ns. Cyst proximate, proximochorate, cavate, acavate, spheroidal, ovoidal, ovaloidal, biconical, peridinioidal, of varying size. Wall composed of pedium and luxuria; surface glabrous, ornamented, nonareate, areate. ... Archeopyle anterior intercalary, 1a = 2a = 3a; operculum solvate, secate, general opercular formula 1a + 2a + 3a. Hebecysta differs from Heibergella in being two-walled.