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Meiourogonyaulax
From Williams et al., 2017:
[Meiourogonyaulax, Sarjeant, 1966b, p. 144
Name was not validly published in Sarjeant (1965, p.181), who did not provide a diagnosis.
Tax. sen. syn.: Lithodinia, according to Gocht, 1975, Fenton, 1981, Dodekova, 1990, and Williams et al., 1993. Stover and Evitt, 1978, Lentin and Williams, 1981, and Riding and Helby, 2001d retained Meiourogonyaulax as a separate genus.
Type species: originally as Gonyaulax sp., Valensi, 1953 (pl.12, figs.12–13)] ; Meiourogonyaulax valensii, Sarjeant, 1966
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Original description: [Sarjeant, 1966]:
Diagnosis:
Proximate dinoflagellate cysts, spherical, ellipsoidal, ovoidal or polyhedral, with the tabulation 4`, 0-1a, 6``, 6g, 5-6```, 0-1p, 0-1p.v., 1````. Cingulum strongly or weakly helicoid; sulcus generally or constantly extending on to epitract. Sutures in form of low ridges or bearing crests of varied form (smooth, denticulate or spinous; perforate or imperforate). Height of crests always less than 1/4 of shell width. Surface smooth, granular, nodose, punctate or reticulate. Archaeopyle formed by loss of apical plates, part of plate 1` sometimes left attached to shell; not all individuals show an archaeopyle.
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Modified description:
Stover and Evitt, 1978, p. 62-63:
Synopsis:
Cyst proximochorate, subspherical, gonyaulacacean; generally complete paratabulation indicated by smooth, continuous, parasutural ridges or septa of essentially uniform height; archeopyle apical, Type (tA).
Description:
Shape: Subspherical.
Wall relationships: Autophragm only.
Wall features: Parasutural ridges and septa characteristically smooth, continuous, occasionally perforate or striate, and of essentially uniform height. Autophragm between parasutural ridges or septa smooth or with features of low relief.
Paratabulation: Clearly and generally completely expressed by parasutural features, gonyaulacacean, formula: 4`, 0-1a, 6``, 6c, 5-6```, 1p, 1````, 0-3s. When five postcingular paraplates are delimited, they are interpreted as corresponding to plates 2``` to 6```.
Archeopyle: Apical, Type (tA); principal archeopyle suture zigzag; operculum free.
Paracingulum:- Indicated by six transversely elongate, rectangular paraplates.
Parasulcus: Indicated by bordering parasutural features; may be subdivided.
Size: Small to intermediate.
Affinities:
Meiourogonyaulax differs from Lithodinia in having a Type (tA) archeopyle rather than a Type 4A archeopyle. It differs further form Lithodinia in generally having continuous, smooth parasutural ridges or septa that are typically higher than those on Lithodinia. Parasutural features on Lithodinia are usually discontinuous and low.
[Meiourogonyaulax, Sarjeant, 1966b, p. 144
Name was not validly published in Sarjeant (1965, p.181), who did not provide a diagnosis.
Tax. sen. syn.: Lithodinia, according to Gocht, 1975, Fenton, 1981, Dodekova, 1990, and Williams et al., 1993. Stover and Evitt, 1978, Lentin and Williams, 1981, and Riding and Helby, 2001d retained Meiourogonyaulax as a separate genus.
Type species: originally as Gonyaulax sp., Valensi, 1953 (pl.12, figs.12–13)] ; Meiourogonyaulax valensii, Sarjeant, 1966
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Original description: [Sarjeant, 1966]:
Diagnosis:
Proximate dinoflagellate cysts, spherical, ellipsoidal, ovoidal or polyhedral, with the tabulation 4`, 0-1a, 6``, 6g, 5-6```, 0-1p, 0-1p.v., 1````. Cingulum strongly or weakly helicoid; sulcus generally or constantly extending on to epitract. Sutures in form of low ridges or bearing crests of varied form (smooth, denticulate or spinous; perforate or imperforate). Height of crests always less than 1/4 of shell width. Surface smooth, granular, nodose, punctate or reticulate. Archaeopyle formed by loss of apical plates, part of plate 1` sometimes left attached to shell; not all individuals show an archaeopyle.
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Modified description:
Stover and Evitt, 1978, p. 62-63:
Synopsis:
Cyst proximochorate, subspherical, gonyaulacacean; generally complete paratabulation indicated by smooth, continuous, parasutural ridges or septa of essentially uniform height; archeopyle apical, Type (tA).
Description:
Shape: Subspherical.
Wall relationships: Autophragm only.
Wall features: Parasutural ridges and septa characteristically smooth, continuous, occasionally perforate or striate, and of essentially uniform height. Autophragm between parasutural ridges or septa smooth or with features of low relief.
Paratabulation: Clearly and generally completely expressed by parasutural features, gonyaulacacean, formula: 4`, 0-1a, 6``, 6c, 5-6```, 1p, 1````, 0-3s. When five postcingular paraplates are delimited, they are interpreted as corresponding to plates 2``` to 6```.
Archeopyle: Apical, Type (tA); principal archeopyle suture zigzag; operculum free.
Paracingulum:- Indicated by six transversely elongate, rectangular paraplates.
Parasulcus: Indicated by bordering parasutural features; may be subdivided.
Size: Small to intermediate.
Affinities:
Meiourogonyaulax differs from Lithodinia in having a Type (tA) archeopyle rather than a Type 4A archeopyle. It differs further form Lithodinia in generally having continuous, smooth parasutural ridges or septa that are typically higher than those on Lithodinia. Parasutural features on Lithodinia are usually discontinuous and low.