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Acanthaulax
From Fensome et al., 2019:
Acanthaulax, Sarjeant, 1968, p. 227.
Emendations: Sarjeant, 1982b, p. 46; Brenner, 1988, p. 33.
Substitute name for Acanthogonyaulax, Sarjeant, 1966b, p.132 (an illegitimate name).
Taxonomic senior synonym: Cribroperidinium, according to Poulsen (1996, p.71).
Taxonomic junior synonym: Meristaulax Sarjeant, by implication in Brenner (1988, p.35), who included the type of Meristaulax Sarjeant in Acanthaulax.
Type: Klement, 1960, pl.5, figs.10–11, as Gonyaulax venusta.
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Original description Acanthogonyaulax: [Sarjeant, 1966, p. 132]:
Description:
Proximate dinoflagellate cysts, spherical, ellipsoidal, ovoidal or polyhedral, with the tabulation 3-4`, 0-1a, 6``, 6g, 6```, 1p, 0-1p.v., 1````.
Cingulum strongly or weakly helicoid; sulcus generally or constantly extending onto epitract.
Apical horn present only infrequently; median and antapical horns lacking.
Sutures in form of low ridges bearing rows of spines.
Shell bearing general cover of simple or furcate spines, identical to or differing from those on sutures; spines fewer or totally lacking on cingulum and/or sulcus. Length of spines always less than 1/4 of shell width.
Surface smooth, granular, nodose, punctate or reticulate.
Precingular archeopyle formed by loss of plate 3``.
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Modified description:
Stover and Evitt, 1978, p. 136:
Synopsis: Cysts proximochorate, subspherical, with or without apical protrusion; paratabulation gonyaulacacean, indicated by parasutural ridges with spines or simply rows of spines; spines or tubercles present between parasutural features; archeopyle precingular, Type P.
Description:
Shape: Subspherical, with or without a short apical protrusion.
Wall relationships: Autophragm only.
Wall features: Parasutural features are low ridges with spinose crests or simply rows of spines. Nontabular spines or tubercles present between parasutural features; surface between spines smooth or has features of low relief .
Paratabulation: Indicated by parasutural features; gonyaulacacean, formula: 3-4`, 0-1a, 6", X or 6c, 6```, 1p, 1````; may be expressed incompletely.
Archeopyle: Precingular, Type P (3" only); operculum free.
Paracingulum: Indicated by six generally rectangular paraplates, or simply by transverse parallel parasutural ridges; indicated in some cases also by a reduction in ornamentation density or the absence of ornamentation.
Parasulcus: Area bordered by parasutural ridges; smooth or less densely ornamented than paraplates.
Size: Intermediate.
Affinities:
Acanthaulax differs from Hystrichogonyaulax in having spines or tubercles in areas between parasutural ridges or rows of spines. These areas on Hystrichogonyaulax lack spines or tubercles.
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Emended descriptions:
Sarjeant, 1982:
Diagnosis:
Proximate to proximochorate dinoflagellate cysts typically of small to intermediate size. Ambitus ovoidal to ellipsoidal or subpolygonal, with or without an apical horn or prominence; typically acavate, but horned forms may be acrocavate or cornucavate. The sutures bear a line of spines or low creasts, perforate but distally entire. The surface of the phragma bears a general cover of spines or coarse tubercles; these are most often absent from a part, or the whole, of the sulcus and may also be lacking from the cingulum.
The paratabulation may be discernible with ease or with difficulty, according to the nature of the sutural ornament and the density of the general cover of spines and tubercules. Paratabulation ?0pa, 4`, ?0-2a, 6``, 6c, 6```, 1p, 0-1pv, 1````; sulcus undivided or showing partial or complete subdivition into paraplates. Paraplate 4` is quite large and roughly quadrate having a moderately long boundary with a reduced 6``. The boundary between 4` and 6`` intersects with a right lateral boundary of 1` in a position anterior to, or almost at the level of, the junction of the latter paraplate with the sulcus.
Cingulum strongly or weakly helicoid; between its two ends, the sulcus is typically straight. Surface of phragm between spines and tubercles smooth or granular.
Archeopyle single-plate precingular, formed by loss of paraplate 3``, operculum reduced.
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Brenner, 1988: (Translation Brenner, 1988: LPP)
Diagnosis:
Proximate to proximochorate dinoflagellate cyst with an apical horn of variable size. The cyst wall consists of a thin "inner membrane" and a "principal cyst wall" with spongy structure of variable density. Parasutural ridges, rims, anuli (lines parallel to the plate-sutures), vestigia (lines perpendicular to the plate-sutures) and short processes and/or spines are formed by the thickening of the principal cyst wall. The paratabulation is gonyaulacoid. The parasuture 3``/4`` is located opposite the parasuture 4```/5```.
The archaeopyle is precingular, type P(3``), or combination precingular/epicystal.
Affinities:
Acanthaulax differs from Cribroperidinium in the relative position of the paraplates. The main difference is the position of precingular 3`` relative to postcingular 4``` (Acanthaulax: slight dextral diplacement; Cribroperidinium: dextral displacement over 1/2 plate`s width). Acanthaulax differs from Apteodinium, Trichodinium and Xenicodinium in the presence of a paratabulation. Liesbergia possesses a horn consisting of anastomosing fibres, Acanthaulax has a solid horn. Tehamadinium has a different archeopyle type.
Acanthaulax, Sarjeant, 1968, p. 227.
Emendations: Sarjeant, 1982b, p. 46; Brenner, 1988, p. 33.
Substitute name for Acanthogonyaulax, Sarjeant, 1966b, p.132 (an illegitimate name).
Taxonomic senior synonym: Cribroperidinium, according to Poulsen (1996, p.71).
Taxonomic junior synonym: Meristaulax Sarjeant, by implication in Brenner (1988, p.35), who included the type of Meristaulax Sarjeant in Acanthaulax.
Type: Klement, 1960, pl.5, figs.10–11, as Gonyaulax venusta.
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Original description Acanthogonyaulax: [Sarjeant, 1966, p. 132]:
Description:
Proximate dinoflagellate cysts, spherical, ellipsoidal, ovoidal or polyhedral, with the tabulation 3-4`, 0-1a, 6``, 6g, 6```, 1p, 0-1p.v., 1````.
Cingulum strongly or weakly helicoid; sulcus generally or constantly extending onto epitract.
Apical horn present only infrequently; median and antapical horns lacking.
Sutures in form of low ridges bearing rows of spines.
Shell bearing general cover of simple or furcate spines, identical to or differing from those on sutures; spines fewer or totally lacking on cingulum and/or sulcus. Length of spines always less than 1/4 of shell width.
Surface smooth, granular, nodose, punctate or reticulate.
Precingular archeopyle formed by loss of plate 3``.
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Modified description:
Stover and Evitt, 1978, p. 136:
Synopsis: Cysts proximochorate, subspherical, with or without apical protrusion; paratabulation gonyaulacacean, indicated by parasutural ridges with spines or simply rows of spines; spines or tubercles present between parasutural features; archeopyle precingular, Type P.
Description:
Shape: Subspherical, with or without a short apical protrusion.
Wall relationships: Autophragm only.
Wall features: Parasutural features are low ridges with spinose crests or simply rows of spines. Nontabular spines or tubercles present between parasutural features; surface between spines smooth or has features of low relief .
Paratabulation: Indicated by parasutural features; gonyaulacacean, formula: 3-4`, 0-1a, 6", X or 6c, 6```, 1p, 1````; may be expressed incompletely.
Archeopyle: Precingular, Type P (3" only); operculum free.
Paracingulum: Indicated by six generally rectangular paraplates, or simply by transverse parallel parasutural ridges; indicated in some cases also by a reduction in ornamentation density or the absence of ornamentation.
Parasulcus: Area bordered by parasutural ridges; smooth or less densely ornamented than paraplates.
Size: Intermediate.
Affinities:
Acanthaulax differs from Hystrichogonyaulax in having spines or tubercles in areas between parasutural ridges or rows of spines. These areas on Hystrichogonyaulax lack spines or tubercles.
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Emended descriptions:
Sarjeant, 1982:
Diagnosis:
Proximate to proximochorate dinoflagellate cysts typically of small to intermediate size. Ambitus ovoidal to ellipsoidal or subpolygonal, with or without an apical horn or prominence; typically acavate, but horned forms may be acrocavate or cornucavate. The sutures bear a line of spines or low creasts, perforate but distally entire. The surface of the phragma bears a general cover of spines or coarse tubercles; these are most often absent from a part, or the whole, of the sulcus and may also be lacking from the cingulum.
The paratabulation may be discernible with ease or with difficulty, according to the nature of the sutural ornament and the density of the general cover of spines and tubercules. Paratabulation ?0pa, 4`, ?0-2a, 6``, 6c, 6```, 1p, 0-1pv, 1````; sulcus undivided or showing partial or complete subdivition into paraplates. Paraplate 4` is quite large and roughly quadrate having a moderately long boundary with a reduced 6``. The boundary between 4` and 6`` intersects with a right lateral boundary of 1` in a position anterior to, or almost at the level of, the junction of the latter paraplate with the sulcus.
Cingulum strongly or weakly helicoid; between its two ends, the sulcus is typically straight. Surface of phragm between spines and tubercles smooth or granular.
Archeopyle single-plate precingular, formed by loss of paraplate 3``, operculum reduced.
------------------------------
Brenner, 1988: (Translation Brenner, 1988: LPP)
Diagnosis:
Proximate to proximochorate dinoflagellate cyst with an apical horn of variable size. The cyst wall consists of a thin "inner membrane" and a "principal cyst wall" with spongy structure of variable density. Parasutural ridges, rims, anuli (lines parallel to the plate-sutures), vestigia (lines perpendicular to the plate-sutures) and short processes and/or spines are formed by the thickening of the principal cyst wall. The paratabulation is gonyaulacoid. The parasuture 3``/4`` is located opposite the parasuture 4```/5```.
The archaeopyle is precingular, type P(3``), or combination precingular/epicystal.
Affinities:
Acanthaulax differs from Cribroperidinium in the relative position of the paraplates. The main difference is the position of precingular 3`` relative to postcingular 4``` (Acanthaulax: slight dextral diplacement; Cribroperidinium: dextral displacement over 1/2 plate`s width). Acanthaulax differs from Apteodinium, Trichodinium and Xenicodinium in the presence of a paratabulation. Liesbergia possesses a horn consisting of anastomosing fibres, Acanthaulax has a solid horn. Tehamadinium has a different archeopyle type.