Back
Stoveracysta
From Williams et al., 2017:
[Stoveracysta, Clowes, 1985, p. 29-30
Type species: Stoveracysta kakanuiensis, Clowes, 1985 (pl.1, figs.1–3)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Clowes, 1985]:
Diagnosis:
Proximate to proximochorate single-layered cyst, subspherical in shape, lacking horns, ornamented by sutural to penitabular ridges or septa delineating a gonyaulacacean tabulation, formula: 4`, 6``, X to 6c, 6```, 1p, 1````, x to 4s. The four plates of the apical series are developed subequally. The sulcal notch is not deep. Plate 1``` is very small, poorly delimited, and intimately associated with the sulcus. Plates 1p and ps are large. The antapical plate is clearly sexiform; it is in contact with plates 1p, 3``` through 6``` and ps.
Archaeopyle apical, type tA; operculum free.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams 1987, p. 205-206:
Synopsis:
Cysts proximate, subspherical to ellipsoidal, with parasutural and/or penitabular ridges which indicate a gonyaulacacean paratabulation; hypocystal paratabulation pattern sexiform; archeopyle apical, type [4A].
Description:
Shape: Subspherical to ellipsoidal; antapical margin may be lobate.
Wall relationships: Autophragm only; outer part of autophragm elevated locally to form parasutural folds or penitabular ridges.
Wall features: Elevated parasutural and/or penitabular structures thin, diaphanous; intratabular areas granular to irregularly scabrate or finely rugulate.
Archeopyle: Apical, type [4A], principal archeopyle suture angular, accessory sutures rarely developed; operculum free.
Paratabulation: Indicated by six, generally transversely elongate, irregularly elliptical, low ridges or a continuous, single (posterior) essentially equatorial ridge together with an incomplete latero-dorsal ridge (anterior) on some specimens.
Parasulcus: Indicated anteriorly by sulcal notch and posteriorly sulcal paraplate; intervening area may have two, poorly or incompletely delimited sulcal paraplates.
Size: Intermediate, complete specimens about 60 µm to 75 µm in length.
Affinities:
Stoveracysta differs from Schematophora Deflandre and Cookson 1955 in having the paracingulum expressed mainly by a single equatorial ridge or by six transversely-elongate, irregularly, elliptical ridges, and conspicuously larger ventral apical paraplates. The paracingulum on Schematophora is indicated by the absence of equatorial structures.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Stoveracysta Clowes, 1985. Stover and Williams (1987, p.205) provided the following synopsis. Cysts proximate, subspherical to ellipsoidal, with parasutural and/or penitabular ridges which indicate a gonyaulacacean paratabulation; hypocystal paratabulation pattern sexiform; archeopyle apical, type (4A).
[Stoveracysta, Clowes, 1985, p. 29-30
Type species: Stoveracysta kakanuiensis, Clowes, 1985 (pl.1, figs.1–3)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Clowes, 1985]:
Diagnosis:
Proximate to proximochorate single-layered cyst, subspherical in shape, lacking horns, ornamented by sutural to penitabular ridges or septa delineating a gonyaulacacean tabulation, formula: 4`, 6``, X to 6c, 6```, 1p, 1````, x to 4s. The four plates of the apical series are developed subequally. The sulcal notch is not deep. Plate 1``` is very small, poorly delimited, and intimately associated with the sulcus. Plates 1p and ps are large. The antapical plate is clearly sexiform; it is in contact with plates 1p, 3``` through 6``` and ps.
Archaeopyle apical, type tA; operculum free.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams 1987, p. 205-206:
Synopsis:
Cysts proximate, subspherical to ellipsoidal, with parasutural and/or penitabular ridges which indicate a gonyaulacacean paratabulation; hypocystal paratabulation pattern sexiform; archeopyle apical, type [4A].
Description:
Shape: Subspherical to ellipsoidal; antapical margin may be lobate.
Wall relationships: Autophragm only; outer part of autophragm elevated locally to form parasutural folds or penitabular ridges.
Wall features: Elevated parasutural and/or penitabular structures thin, diaphanous; intratabular areas granular to irregularly scabrate or finely rugulate.
Archeopyle: Apical, type [4A], principal archeopyle suture angular, accessory sutures rarely developed; operculum free.
Paratabulation: Indicated by six, generally transversely elongate, irregularly elliptical, low ridges or a continuous, single (posterior) essentially equatorial ridge together with an incomplete latero-dorsal ridge (anterior) on some specimens.
Parasulcus: Indicated anteriorly by sulcal notch and posteriorly sulcal paraplate; intervening area may have two, poorly or incompletely delimited sulcal paraplates.
Size: Intermediate, complete specimens about 60 µm to 75 µm in length.
Affinities:
Stoveracysta differs from Schematophora Deflandre and Cookson 1955 in having the paracingulum expressed mainly by a single equatorial ridge or by six transversely-elongate, irregularly, elliptical ridges, and conspicuously larger ventral apical paraplates. The paracingulum on Schematophora is indicated by the absence of equatorial structures.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Stoveracysta Clowes, 1985. Stover and Williams (1987, p.205) provided the following synopsis. Cysts proximate, subspherical to ellipsoidal, with parasutural and/or penitabular ridges which indicate a gonyaulacacean paratabulation; hypocystal paratabulation pattern sexiform; archeopyle apical, type (4A).