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Dioxya
From Fensome et al., 2019:
Dioxya, Cookson and Eisenack, 1958, p.59.
Emendation: Morgan, 1977, p.131.
Taxonomic junior synonym: Vozzhennikovia, according to Morgan (1977, p.131) -- however, Lentin and Williams (1981, p.88) retained Vozzhennikovia.
Type: Cookson and Eisenack, 1958, pl.11, fig.11; text-fig.20, as Dioxya armata.
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Original description: [Cookson and Eisenack, 1958]:
Description:
Shell fusiform, without plates and girdle, and with the two ends closed and of different shapes.
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Emended description:
Morgan, 1977:
Description:
Shape: Ambitus rounded to ovoidal, apex drawn into a broad, truncate, apical horn, antapex drawn into a broad, eccentrically located, single antapical horn. Rarely, two unequal, symmetrically located antapical horns are developed. Epicyst and hypocyst approximately of equal size, or epicyst slightly larger.
Phragma: Usually apparent autophragm bears spines which are nontabular except in the precingular and parasulcal regions. Rare development of an ovoidal endophragm may produce small pericoels at the horns. Autocyst or pericyst nontabular except at the archaeopyle. Paracingulum defined by two rows of aligned spines. Area of paracingulum between parasutures devoid of ornamentation. Parasulcus delineated by absence of ornamentation, extends slightly onto epicyst, extents almost to antapex on hypocyst. Endophragm, when developed, psilate.
Archaeopyle: Standard hexa Ia. Wall layers always closely appressed in the vicinity of the archaeopyle.
Affinities:
Dioxya is characterized by its oval ambitus, with broad apical and single eccentrically located, or two unequal, antapical horn(s), usual autophragm, nontabular spines, and intercalary archaeopyle.
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Modified description:
Stover and Evitt, 1978, p. 103:
Synopsis:
Cysts proximochorate, ellipsoidal, with single short apical and antapical horns or protrusions; autophragm with solid nontabular spines except along paracingulum, where spines are aligned in two transverse rows; archeopyle intercalary, Type la.
Description:
Shape: Ellipsoidal with single short horns or protrusions at each pole.
Wall relationships: Autophragm only.
Wall features: No parasutural features. Solid spines nontabular except along paracingulum; autophragm smooth.
Paratabulation: Indicated by archeopyle and paracingulum.
Archeopyle: Intercalary, Type la (2a only); operculum attached.
Paracingulum: Indicated by two parallel, transverse, equatorial rows of spines.
Parasulcus: Expressed as unornamented area mainly on the hypocyst.
Size: Small to intermediate.
Affinities:
Dioxya differs from Vozzhennikovia in having an autophragm only and in having a single antapical horn or projection near or at the longitudinal axis. Vozzhennikovia has two wall layers and, generally, two antapical horns; however, if only one antapical horn is developed, it is not near the longitudinal midline.
Dioxya, Cookson and Eisenack, 1958, p.59.
Emendation: Morgan, 1977, p.131.
Taxonomic junior synonym: Vozzhennikovia, according to Morgan (1977, p.131) -- however, Lentin and Williams (1981, p.88) retained Vozzhennikovia.
Type: Cookson and Eisenack, 1958, pl.11, fig.11; text-fig.20, as Dioxya armata.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Cookson and Eisenack, 1958]:
Description:
Shell fusiform, without plates and girdle, and with the two ends closed and of different shapes.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Morgan, 1977:
Description:
Shape: Ambitus rounded to ovoidal, apex drawn into a broad, truncate, apical horn, antapex drawn into a broad, eccentrically located, single antapical horn. Rarely, two unequal, symmetrically located antapical horns are developed. Epicyst and hypocyst approximately of equal size, or epicyst slightly larger.
Phragma: Usually apparent autophragm bears spines which are nontabular except in the precingular and parasulcal regions. Rare development of an ovoidal endophragm may produce small pericoels at the horns. Autocyst or pericyst nontabular except at the archaeopyle. Paracingulum defined by two rows of aligned spines. Area of paracingulum between parasutures devoid of ornamentation. Parasulcus delineated by absence of ornamentation, extends slightly onto epicyst, extents almost to antapex on hypocyst. Endophragm, when developed, psilate.
Archaeopyle: Standard hexa Ia. Wall layers always closely appressed in the vicinity of the archaeopyle.
Affinities:
Dioxya is characterized by its oval ambitus, with broad apical and single eccentrically located, or two unequal, antapical horn(s), usual autophragm, nontabular spines, and intercalary archaeopyle.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt, 1978, p. 103:
Synopsis:
Cysts proximochorate, ellipsoidal, with single short apical and antapical horns or protrusions; autophragm with solid nontabular spines except along paracingulum, where spines are aligned in two transverse rows; archeopyle intercalary, Type la.
Description:
Shape: Ellipsoidal with single short horns or protrusions at each pole.
Wall relationships: Autophragm only.
Wall features: No parasutural features. Solid spines nontabular except along paracingulum; autophragm smooth.
Paratabulation: Indicated by archeopyle and paracingulum.
Archeopyle: Intercalary, Type la (2a only); operculum attached.
Paracingulum: Indicated by two parallel, transverse, equatorial rows of spines.
Parasulcus: Expressed as unornamented area mainly on the hypocyst.
Size: Small to intermediate.
Affinities:
Dioxya differs from Vozzhennikovia in having an autophragm only and in having a single antapical horn or projection near or at the longitudinal axis. Vozzhennikovia has two wall layers and, generally, two antapical horns; however, if only one antapical horn is developed, it is not near the longitudinal midline.