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Eisenackia
From Williams et al., 2017:
[Eisenackia, Deflandre and Cookson, 1955, p. 258; Emendations: Sarjeant, 1966b, p.152; Davey, 1969b, p.3, as a revised diagnosis; McLean, 1973a, p.262; Quattrocchio and Sarjeant, 2003, p.144.
Eisenackia was not validly published in Deflandre and Cookson (1954, p.1237), since no description was given.
Tax. jun. syn.: Alisocysta and Agerasphaera (name illegitimate), both according to Quattrocchio and Sarjeant (2003, p.144) — however, Fensome et al. (in press) retained Alisocysta, with Agerasphaera as its nomenclatural junior synonym.
Type species: Eisenackia crassitabulata, Deflandre and Cookson, 1955 (pl.5, fig.2)] ; emend McLean, 1973
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Original description: [Deflandre and Cookson, 1955]:
Description:
Cell globular without appendages. Transverse girdle and longitudinal furrow not marked by a depression of the membrane which has a completely continuous outline. Transverse girdle delimited by the bases of the plates. Tabulation 2-3`, 6", ?6g, 6```, 2p, 1````. The epitheca has, amongst others, an elongated ventral plate and the hypotheca a ventral area consisting of several small plates.
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Emended descriptions:
Sarjeant, 1966:
Description:
Proximate dinoflagellate cysts, spheroidal or ovoidal in shape, with the tabulation 2-3 `, 6 ", ?6c, 6```, 2p, 1````; additional plates occupy ventral area, there being no sulcus as such. Plates consisting of raised areas of shell surface, isolated from one another by pattern of `channels` corresponding in position to sutures. (It is here proposed that such inverse equivalents of sutures be termed `fossae`.) Cingulum weakly helicoid. Shell surface typically reticulate, possibly also granular or punctate. Apical archeopyle formed by loss of apical plates.
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McLean, 1973:
Description:
Cysts spheroidal to ellipsoidal, lacking horns or processes; bilayered; outer wall layer occurs in shapes of plate equivalents superimposed on inner layer, reflecting tabulation of 4`, 0a, 6", 6c, 6```, 1p, 1````.
Archeopyle apical (Type A) with simple, free operculum.
Cingulum and sulcus reflected by plate quivalents.
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Modified description:
Stover and Evitt, 1978, p. 42
Synopsis: Cysts proximochorate, subspherical; paratabulation gonyaulacacean, indicated by raised platformlike features separated by parasutural depressions; archeopyle apical, Type tA.
Description:
Shape: Subspherical.
Wall relationships: Autophragm only.
Wall features: Parasutural features are relatively narrow linear depressions between raised intratabular areas.
Paratabulation: Excellently expressed by parasutural and intratabular features; gonyaulacacean, formula: 3-?4`, 6", 6c, 6```, 1p, 1````, 1-5s. We interpret the paraplate designated 2p to be paraplate ps.
Archeopyle: Apical, Type tA; principal archeopyle suture zigzag with deep parasulcal notch; operculum free and probably has four apical paraplates rather than three, as indicated in original drawings (Deflandre & Cookson, 1955, p. 259, fig. 8-10).
Paracingulum: Indicated by six rectangular paraplates.
Parasulcus: Occupied by two to five clearly separated paraplates; anterior and posterior paraplates nearly always present and larger than the others.
Size: Intermediate.
Affinities:
Eisenackia differs from Cassidium in having wider and generally deeper parasutural depressions, and in having paraplates expressed in the parasulcus. In Cassidium, paraplates are not indicated in the parasulcus. Alisocysta has parasutural ridges or septa rather than depressions, as in Eisenackia.
[Eisenackia, Deflandre and Cookson, 1955, p. 258; Emendations: Sarjeant, 1966b, p.152; Davey, 1969b, p.3, as a revised diagnosis; McLean, 1973a, p.262; Quattrocchio and Sarjeant, 2003, p.144.
Eisenackia was not validly published in Deflandre and Cookson (1954, p.1237), since no description was given.
Tax. jun. syn.: Alisocysta and Agerasphaera (name illegitimate), both according to Quattrocchio and Sarjeant (2003, p.144) — however, Fensome et al. (in press) retained Alisocysta, with Agerasphaera as its nomenclatural junior synonym.
Type species: Eisenackia crassitabulata, Deflandre and Cookson, 1955 (pl.5, fig.2)] ; emend McLean, 1973
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Original description: [Deflandre and Cookson, 1955]:
Description:
Cell globular without appendages. Transverse girdle and longitudinal furrow not marked by a depression of the membrane which has a completely continuous outline. Transverse girdle delimited by the bases of the plates. Tabulation 2-3`, 6", ?6g, 6```, 2p, 1````. The epitheca has, amongst others, an elongated ventral plate and the hypotheca a ventral area consisting of several small plates.
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Emended descriptions:
Sarjeant, 1966:
Description:
Proximate dinoflagellate cysts, spheroidal or ovoidal in shape, with the tabulation 2-3 `, 6 ", ?6c, 6```, 2p, 1````; additional plates occupy ventral area, there being no sulcus as such. Plates consisting of raised areas of shell surface, isolated from one another by pattern of `channels` corresponding in position to sutures. (It is here proposed that such inverse equivalents of sutures be termed `fossae`.) Cingulum weakly helicoid. Shell surface typically reticulate, possibly also granular or punctate. Apical archeopyle formed by loss of apical plates.
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McLean, 1973:
Description:
Cysts spheroidal to ellipsoidal, lacking horns or processes; bilayered; outer wall layer occurs in shapes of plate equivalents superimposed on inner layer, reflecting tabulation of 4`, 0a, 6", 6c, 6```, 1p, 1````.
Archeopyle apical (Type A) with simple, free operculum.
Cingulum and sulcus reflected by plate quivalents.
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Modified description:
Stover and Evitt, 1978, p. 42
Synopsis: Cysts proximochorate, subspherical; paratabulation gonyaulacacean, indicated by raised platformlike features separated by parasutural depressions; archeopyle apical, Type tA.
Description:
Shape: Subspherical.
Wall relationships: Autophragm only.
Wall features: Parasutural features are relatively narrow linear depressions between raised intratabular areas.
Paratabulation: Excellently expressed by parasutural and intratabular features; gonyaulacacean, formula: 3-?4`, 6", 6c, 6```, 1p, 1````, 1-5s. We interpret the paraplate designated 2p to be paraplate ps.
Archeopyle: Apical, Type tA; principal archeopyle suture zigzag with deep parasulcal notch; operculum free and probably has four apical paraplates rather than three, as indicated in original drawings (Deflandre & Cookson, 1955, p. 259, fig. 8-10).
Paracingulum: Indicated by six rectangular paraplates.
Parasulcus: Occupied by two to five clearly separated paraplates; anterior and posterior paraplates nearly always present and larger than the others.
Size: Intermediate.
Affinities:
Eisenackia differs from Cassidium in having wider and generally deeper parasutural depressions, and in having paraplates expressed in the parasulcus. In Cassidium, paraplates are not indicated in the parasulcus. Alisocysta has parasutural ridges or septa rather than depressions, as in Eisenackia.