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Ithnacysta
From Williams et al., 2017:
[Ithnacysta, Slimani, 1994, p. 107
Type species: Ithnacysta elongata, Slimani, 1994 (pl.18, figs.27–29)]
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Original description: [Slimani, 1994]: (Translation: LPP):
Diagnosis:
Proximate, fusiform, cornucavate or circumcavate cyst, lacking parasutures. The endocyst is ovoidal or ellipsoidal. The endophragm and periphragm are smooth or decorated with low ornaments (punctae, scabrae or granulae).
The archaeopyle is intercalary type 2Ia; the operculum comprises 2 intercalary paraplates attached to the posterior margin of the archaeopyle. The paracingulum and parasulcus are not indicated.
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Slimani, 1994, p. 107:
Affinities:
Ithnacysta differs from all other genera in the combination of the following characteristics: a biconical shape of the cyst and the presence of an endocyst and a type 2Ia intercalary archaeopyle. Consequently, it differs from Palaeocystodinium Alberti, 1961 solely in its 2Ia type archaeopyle, and from Svalbardella Manum, 1960 in its archaeopyle and the absence of a paracingulum. Fusiformacysta Morgan, 1975 has a cyst formed by an autophragm and presents a type 2p-?5p precingular archaeopyle with a free operculum.
[Ithnacysta, Slimani, 1994, p. 107
Type species: Ithnacysta elongata, Slimani, 1994 (pl.18, figs.27–29)]
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Original description: [Slimani, 1994]: (Translation: LPP):
Diagnosis:
Proximate, fusiform, cornucavate or circumcavate cyst, lacking parasutures. The endocyst is ovoidal or ellipsoidal. The endophragm and periphragm are smooth or decorated with low ornaments (punctae, scabrae or granulae).
The archaeopyle is intercalary type 2Ia; the operculum comprises 2 intercalary paraplates attached to the posterior margin of the archaeopyle. The paracingulum and parasulcus are not indicated.
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Slimani, 1994, p. 107:
Affinities:
Ithnacysta differs from all other genera in the combination of the following characteristics: a biconical shape of the cyst and the presence of an endocyst and a type 2Ia intercalary archaeopyle. Consequently, it differs from Palaeocystodinium Alberti, 1961 solely in its 2Ia type archaeopyle, and from Svalbardella Manum, 1960 in its archaeopyle and the absence of a paracingulum. Fusiformacysta Morgan, 1975 has a cyst formed by an autophragm and presents a type 2p-?5p precingular archaeopyle with a free operculum.