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Emmetrocysta
From Williams et al., 2017:
[Emmetrocysta, Stover, 1975, p. 42
Type species: originally as Cannosphaeropsis urnaformis, Cookson, 1953 (pl.2, figs.41–42)] ; Emmetrocysta urnaformis, Stover, 1975
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Original description: [Stover, 1975]:
Description:
Cysts spherical or nearly so; wall consists of two appressed wall layers, with periphragm giving rise to 18 or 19 peritabular processes. Process formula gonyaulacacean; 4`, 6``, 0c, 5-6```, 1p, 1````, 2-3s. Processes complex, cylindrical to trumpet shaped, hollow, open and flared distally, sides with circular, elliptical or irregularly shaped, rounded holes of various sizes. Distal ends of processes enclosed by ring trabeculae, and on some specimens, interprocess trabeculae connect adjacent process in and margining the sulcus. Antapical process typically broadly oval to heart shaped, with midventral concavity. Cingulum reflected by process-free area. Archaeopyle apical, Type A, with free operculum. Surface smooth or uniformly ornamented with small scabrae or granulae, or by puncto-reticulation. None of these features is prominent.
Affinities:
Other genera similar to Emmetrocysta are Polystephanephorus Sarjeant, 1961, and Hystrichospaerina Alberti, 1961. Illustrations of the type species of Polystephanephorus, P. calathus (Sarjeant) Downie and Sarjeant, 1964, indicate that it has notably fewer processes than Emmetrocysta urnaformis. Moreover the process formula and archaeopyle type are not known with certainty for Polystephanephorus. The process formula for Hystrichosphaerina is unknown also, but judging from the descriptions of the genus and its type species, plus the illustrations of the holotype and a paratype (Alberti, 1961), Hystrichosphaerina differs from Emmetrocysta by having simple, forked, cingular processes not connected by trabeculae. Cingular processes are not present on Emmetrocysta.
In addition to morphological considerations, there is a wide stratigraphic disparity between Emmetrocysta and the other two genera; Emmetrocysta is known only From the Late Eocene whereas Hystrichosphaerina ranges from the Oxfordian to Seneonian (Late Jurassic to Late Cretaceous), and Polystephanephorus is known only from the Late Jurassic.
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Modified description:
Stover and Evitt, 1978, p. 44-45:
Synopsis:
Cysts skolochorate, gonyaulacacean; body subspherical with 19 to 21 cylindrical to trumpet-shaped, penitabular process groups; processes in each group linked distally by ring trabeculae; process groups and isolated processes absent from paracingulum; archaeopyle apical, Type tA.
Description:
Shape: Body subspherical.
Wall relationships: Autophragm only.
Wall features: No parasutural features. Penitabular process groups cylindrical to trumpet-shaped, linked distally by ring trabeculae; additional trabeculae interconnecting some process groups in and margining parasulcus. Autophragm between process groups smooth or faintly ornamented.
Paratabulation: Indicated by penitabular process groups; gonyaulacacean, process formula 4`, 6``, 0c, 5-6```, 1p, 1````, 2-3s. When five postcingular process groups are present, these are interpreted as occurring on paraplates 2``` to 6```.
Archaeopyle: apical, Type tA; principal archaeopyle suture zigzag; operculum free.
Paracingulum: Indicated by absence of process groups and isolated processes.
Parasulcus: Indicated by presence of two or three parasulcal process groups; margins of parasulcus not delimited.
Size: Intermediate
Affinities:
Emmetrocysta differs from Hystrichosphaerina in lacking paracingular processes and from Systematophora in having the processes in each group linked distally by ring trabeculae.
The relationship between Hystrichosphaerina and Emmetrocysta is comparable to that between Hystrichosphaeridium and Oligosphaeridium.
[Emmetrocysta, Stover, 1975, p. 42
Type species: originally as Cannosphaeropsis urnaformis, Cookson, 1953 (pl.2, figs.41–42)] ; Emmetrocysta urnaformis, Stover, 1975
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Stover, 1975]:
Description:
Cysts spherical or nearly so; wall consists of two appressed wall layers, with periphragm giving rise to 18 or 19 peritabular processes. Process formula gonyaulacacean; 4`, 6``, 0c, 5-6```, 1p, 1````, 2-3s. Processes complex, cylindrical to trumpet shaped, hollow, open and flared distally, sides with circular, elliptical or irregularly shaped, rounded holes of various sizes. Distal ends of processes enclosed by ring trabeculae, and on some specimens, interprocess trabeculae connect adjacent process in and margining the sulcus. Antapical process typically broadly oval to heart shaped, with midventral concavity. Cingulum reflected by process-free area. Archaeopyle apical, Type A, with free operculum. Surface smooth or uniformly ornamented with small scabrae or granulae, or by puncto-reticulation. None of these features is prominent.
Affinities:
Other genera similar to Emmetrocysta are Polystephanephorus Sarjeant, 1961, and Hystrichospaerina Alberti, 1961. Illustrations of the type species of Polystephanephorus, P. calathus (Sarjeant) Downie and Sarjeant, 1964, indicate that it has notably fewer processes than Emmetrocysta urnaformis. Moreover the process formula and archaeopyle type are not known with certainty for Polystephanephorus. The process formula for Hystrichosphaerina is unknown also, but judging from the descriptions of the genus and its type species, plus the illustrations of the holotype and a paratype (Alberti, 1961), Hystrichosphaerina differs from Emmetrocysta by having simple, forked, cingular processes not connected by trabeculae. Cingular processes are not present on Emmetrocysta.
In addition to morphological considerations, there is a wide stratigraphic disparity between Emmetrocysta and the other two genera; Emmetrocysta is known only From the Late Eocene whereas Hystrichosphaerina ranges from the Oxfordian to Seneonian (Late Jurassic to Late Cretaceous), and Polystephanephorus is known only from the Late Jurassic.
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Modified description:
Stover and Evitt, 1978, p. 44-45:
Synopsis:
Cysts skolochorate, gonyaulacacean; body subspherical with 19 to 21 cylindrical to trumpet-shaped, penitabular process groups; processes in each group linked distally by ring trabeculae; process groups and isolated processes absent from paracingulum; archaeopyle apical, Type tA.
Description:
Shape: Body subspherical.
Wall relationships: Autophragm only.
Wall features: No parasutural features. Penitabular process groups cylindrical to trumpet-shaped, linked distally by ring trabeculae; additional trabeculae interconnecting some process groups in and margining parasulcus. Autophragm between process groups smooth or faintly ornamented.
Paratabulation: Indicated by penitabular process groups; gonyaulacacean, process formula 4`, 6``, 0c, 5-6```, 1p, 1````, 2-3s. When five postcingular process groups are present, these are interpreted as occurring on paraplates 2``` to 6```.
Archaeopyle: apical, Type tA; principal archaeopyle suture zigzag; operculum free.
Paracingulum: Indicated by absence of process groups and isolated processes.
Parasulcus: Indicated by presence of two or three parasulcal process groups; margins of parasulcus not delimited.
Size: Intermediate
Affinities:
Emmetrocysta differs from Hystrichosphaerina in lacking paracingular processes and from Systematophora in having the processes in each group linked distally by ring trabeculae.
The relationship between Hystrichosphaerina and Emmetrocysta is comparable to that between Hystrichosphaeridium and Oligosphaeridium.