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Hystrichogonyaulax
From Williams et al., 2017:
[Hystrichogonyaulax, Sarjeant, 1969, p.13–14
Type species: originally as Gonyaulax cornigera, Valensi, 1953 (pl.1, fig.8)] ; Hystrichogonyaulax cornigera, Sarjeant, 1969
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Original description: [Sarjeant, 1969]:
Description:
Proximate dinoflagellate cysts, spheroidal, ovoidal, ellipsoidal or polyhedral, with the reflected tabulation 3-4`, 0-1a, 6``, 6c, 5-6``, 1p, 0-1p.v., 1````, 0-xs. Apical, median and antapical horns lacking.
Cingulum strongly or weakly helicoid, laevorotatory; cingular plates well or poorly marked.
Sulcus generally but not constantly extending onto the epitract, undivided or subdivided into a variable number of small plates.
Rarely, an apical or an antapical pericoel may be present (but not both); the two shell layers are otherwise in continuous contact. Sutures marked by lines or low ridges from which arise isolated spines; the length of spines may vary according to position on the test (e.g., the spines ringing the antapex may be longer than the others), or may be relatively constant. The spines may be simple or may bifurcate or ramify near the tips: their length is constantly less than 1/4 of the longest shell cross-measurement.
A precingular single-plate archaeopyle, formed by loss of plate 3``, is developed.
Surface of periphragm smooth, granular or punctate. Forms with a nodose or reticulate surface have not, to date, been encountered: those with a general spine cover are excluded.
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Modified description:
Stover and Evitt, 1978, p. 162:
Synopsis:
Cysts proximochorate; body subspherical to polyhedral, with or without an apical horn; paratabulation gonyaulacacean, indicated by parasutural ridges surmounted by normally isolated spines; surface between parasutural ridges smooth or faintly ornamented; archeopyle precingular, Type P.
Description:
Shape: Body subspherical to polyhedral; may have an antapical horn.
Wall relationships: Autophragm only, or closely appressed endophragm and periphragm, which may be separated slightly apically or antapically.
Wall features: Parasutural ridges usually low, solid or perforate, distally spinose; spines relatively short to long, normally isolated, open or closed, and simple or branched distally. Autophragm or periphragm between parasutural features smooth or finely ornamented.
Paratabulation: Indicated clearly by parasutural features; gonyaulacacean, formula: 3-4`, 0-1a, 6, Xc-6c, 5-6```, 1p, 1````, 0-1s.
Archeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Indicated by six generally rectangular paraplates, or by parallel transverse ridges.
Parasulcus: Longitudinally elongate area bordered by parasutural ridges; posterior sulcal paraplate may be differentiated.
Size: Intermediate.
Affinities:
Hystrichogonyaulax differs from Acanthaulax in lacking spines or features of low relief between parasutural ridges; these areas on Acanthaulax are ornamented.
[Hystrichogonyaulax, Sarjeant, 1969, p.13–14
Type species: originally as Gonyaulax cornigera, Valensi, 1953 (pl.1, fig.8)] ; Hystrichogonyaulax cornigera, Sarjeant, 1969
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Sarjeant, 1969]:
Description:
Proximate dinoflagellate cysts, spheroidal, ovoidal, ellipsoidal or polyhedral, with the reflected tabulation 3-4`, 0-1a, 6``, 6c, 5-6``, 1p, 0-1p.v., 1````, 0-xs. Apical, median and antapical horns lacking.
Cingulum strongly or weakly helicoid, laevorotatory; cingular plates well or poorly marked.
Sulcus generally but not constantly extending onto the epitract, undivided or subdivided into a variable number of small plates.
Rarely, an apical or an antapical pericoel may be present (but not both); the two shell layers are otherwise in continuous contact. Sutures marked by lines or low ridges from which arise isolated spines; the length of spines may vary according to position on the test (e.g., the spines ringing the antapex may be longer than the others), or may be relatively constant. The spines may be simple or may bifurcate or ramify near the tips: their length is constantly less than 1/4 of the longest shell cross-measurement.
A precingular single-plate archaeopyle, formed by loss of plate 3``, is developed.
Surface of periphragm smooth, granular or punctate. Forms with a nodose or reticulate surface have not, to date, been encountered: those with a general spine cover are excluded.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt, 1978, p. 162:
Synopsis:
Cysts proximochorate; body subspherical to polyhedral, with or without an apical horn; paratabulation gonyaulacacean, indicated by parasutural ridges surmounted by normally isolated spines; surface between parasutural ridges smooth or faintly ornamented; archeopyle precingular, Type P.
Description:
Shape: Body subspherical to polyhedral; may have an antapical horn.
Wall relationships: Autophragm only, or closely appressed endophragm and periphragm, which may be separated slightly apically or antapically.
Wall features: Parasutural ridges usually low, solid or perforate, distally spinose; spines relatively short to long, normally isolated, open or closed, and simple or branched distally. Autophragm or periphragm between parasutural features smooth or finely ornamented.
Paratabulation: Indicated clearly by parasutural features; gonyaulacacean, formula: 3-4`, 0-1a, 6, Xc-6c, 5-6```, 1p, 1````, 0-1s.
Archeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Indicated by six generally rectangular paraplates, or by parallel transverse ridges.
Parasulcus: Longitudinally elongate area bordered by parasutural ridges; posterior sulcal paraplate may be differentiated.
Size: Intermediate.
Affinities:
Hystrichogonyaulax differs from Acanthaulax in lacking spines or features of low relief between parasutural ridges; these areas on Acanthaulax are ornamented.