Back
Alisocysta
From Williams et al., 2017:
[Alisocysta, Stover and Evitt, 1978, p. 15–16.
Tax. sr. syn.: Eisenackia, according to Quattrocchio and Sarjeant (2003, p.144) — however, Fensome et al. (in press) retained Alisocysta
Type species: as Eisenackia circumtabulata, Drugg, 1967 (pl.1, fig.12)]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original descripton: [Stover and Evitt 1978]:
Synopsis: Cyst proximochorate, subspherical; paratabulation gonyaulacacaean, indicated by normally complete penitabular ridges or septa; penitabular features present in paracingulum; archaeopyle apical, Type tA.
Description:
Shape: Body subspherical; a shallow antapical concavity and/or a low-arched apical peak may be present.
Wall Relationships: Autophragm only.
Wall Features: No parasutural features. Penitabular ridges or septa normally complete, smooth or faintly ornamented, occasionally finely perforate, and generally of uniform height. Autophragm between ridges or septa smooth or faintly and uniformly ornamented.
Paratabulation: Paraplates indicated by polygonal areas outlined by penitabular ridges or septa; gonyaulacacean, formula: 4`, 6``, 6c, 6```, 1p, 1````, 2-5s.
Archaeopyle: Apical, Type tA, principal archaeopyle suture zigzag; operculum free, constituent apical paraplates indicated by penitabular ridges or septa. Paracingulum: Indicated by six transversely elongate, nearly rectangular areas outlined by penitabular ridges or septa.
Parasulcus: Indicated by two to five small polygonal areas also outlined by penitabular features. Anterior and posterior paraplates within the parasulcus consistently delimited and typically larger than the others, which may be absent.
Size: Intermediate.
Affinities:
Alisocysta differs from Schematophora in having penitabular ridges in the paracingular areas; such ridges are not present on specimens of Schematophora. Alisocysta differs from Eisenackia in lacking depressed parasutural features (fossae of Sarjeant 1966, p. 152), and in having the paratabulation expressed by penitabular ridges or septa rather than elevated, platform-like features.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5:
Alisocysta Stover and Evitt, 1978. Stover and Evitt (1978, p.15) gave the following synopsis: Cysts proximochorate, subspherical. Paratabulation gonyaulacacean, indicated by normally complete penitabular ridges or septa; penitabular features present in paracingulum; archeopyle apical, type (tA). This genus is included in the Pyrodinioideae of the Goniodomaceae. According to Stover and Evitt (1978) Alisocysta differs from Schematophora in having penitabular ridges on the cingulum. In Eisenackia the intratabular areas are elevated.
[Alisocysta, Stover and Evitt, 1978, p. 15–16.
Tax. sr. syn.: Eisenackia, according to Quattrocchio and Sarjeant (2003, p.144) — however, Fensome et al. (in press) retained Alisocysta
Type species: as Eisenackia circumtabulata, Drugg, 1967 (pl.1, fig.12)]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original descripton: [Stover and Evitt 1978]:
Synopsis: Cyst proximochorate, subspherical; paratabulation gonyaulacacaean, indicated by normally complete penitabular ridges or septa; penitabular features present in paracingulum; archaeopyle apical, Type tA.
Description:
Shape: Body subspherical; a shallow antapical concavity and/or a low-arched apical peak may be present.
Wall Relationships: Autophragm only.
Wall Features: No parasutural features. Penitabular ridges or septa normally complete, smooth or faintly ornamented, occasionally finely perforate, and generally of uniform height. Autophragm between ridges or septa smooth or faintly and uniformly ornamented.
Paratabulation: Paraplates indicated by polygonal areas outlined by penitabular ridges or septa; gonyaulacacean, formula: 4`, 6``, 6c, 6```, 1p, 1````, 2-5s.
Archaeopyle: Apical, Type tA, principal archaeopyle suture zigzag; operculum free, constituent apical paraplates indicated by penitabular ridges or septa. Paracingulum: Indicated by six transversely elongate, nearly rectangular areas outlined by penitabular ridges or septa.
Parasulcus: Indicated by two to five small polygonal areas also outlined by penitabular features. Anterior and posterior paraplates within the parasulcus consistently delimited and typically larger than the others, which may be absent.
Size: Intermediate.
Affinities:
Alisocysta differs from Schematophora in having penitabular ridges in the paracingular areas; such ridges are not present on specimens of Schematophora. Alisocysta differs from Eisenackia in lacking depressed parasutural features (fossae of Sarjeant 1966, p. 152), and in having the paratabulation expressed by penitabular ridges or septa rather than elevated, platform-like features.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5:
Alisocysta Stover and Evitt, 1978. Stover and Evitt (1978, p.15) gave the following synopsis: Cysts proximochorate, subspherical. Paratabulation gonyaulacacean, indicated by normally complete penitabular ridges or septa; penitabular features present in paracingulum; archeopyle apical, type (tA). This genus is included in the Pyrodinioideae of the Goniodomaceae. According to Stover and Evitt (1978) Alisocysta differs from Schematophora in having penitabular ridges on the cingulum. In Eisenackia the intratabular areas are elevated.