Back
Amiculosphaera
From Fensome et al., 2019:
Amiculosphaera, Harland, 1979b, p.535.
Type: Harland, 1979b, pl.2, figs.1–3, as Amiculosphaera umbraculum.
---------------------------------------------------------------------------------------------------
Original description: [Harland, 1979]:
Description:
Cavate cyst with an epitractal, cingular and partly hypotractal pericoel formed by the separation of the periphragm from the endophragm. Periphragm forms an outer `cloak-like` covering to the epitract that may or may not carry traces of a paratabulation but which is attached to the hypotract within the post-cingular series. Periphragm supported at the apex by an apical process that is confluent with the periphragm. Tabulation gonyaulacacean, the archeopyle precingular formed by the loss of 3`` in both the endoblast and periblast.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams, 1987, p. 15:
Synopsis:
Cysts proximate, outline subcircular to rhomboidal in dorsal-ventral view, circumcavate; pericyst basket-shaped, hypopericyst hemispherical, epipericyst composed of transverse meridional band connected to endocyst by a funnel-like apical projection arising from the endocyst; endocyst subspherical; parasutural features incompletely developed; endoarcheopyle type P, 3`` only.
Description:
Shape: Pericyst outline in dorsal-ventral view more or less circular to rhomboidal.
Wall relationships: Cysts circumcavate, endocyst subspherical to ovoidal, attached to pericyst antapically, separated elsewhere; pericyst basket- shaped, hypopericyst hemispherical, epipericyst consists of a transverse, meridional band connected apically to a funnel-like structure arising from the apical pole of the endocyst.
Wall features: Periphragm and endophragm smooth; low parasutural ridges may be present.
Paratabulation: Indicated incompletely by discontinuous, low parasutural ridges mainly on the dorsal surface.
Archeopyle: Precingular, type P, 3`` only and present in endophragm only; operculum free.
Paracingulum: Expressed by a discontinuous, low, transverse, equatorial ridge or ridges.
Parasulcus: Apparently not indicated.
Size: Intermediate, up to 80 µm in diameter.
Affinities:
Amiculosphaera differs from Lophocysta Manum 1979 in the structure of the pericyst. In the former, the periphragm contacts the endophragm only in the antapical polar area and seemingly has little or no contact with the periphragm elsewhere, except at the apical pole where it merges with a funnel-like structure. Thus, Amiculosphaera is essentially circumcavate. In contrast, Lophocysta is camocavate with the periphragm appressed to the endophragm dorsally ad separated from it ventrally. In Invertocysta Edwards 1984, the pericyst is bowl-shaped, appressed to the endocyst in the midventral region and has a large dorsal opening. In Thalassiphora Eisenack and Gocht 1960 emended Benedek and Gocht 1981, the periphragm is open ventrally and appressed to the endophragm dorsally.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Amiculosphaera, Harland, 1979b. Stover and Williams (1987, p. 15) gave the following synopsis. Cysts proximate, outline subcircular to rhomboidal in dorsal-ventral view, circumcavate; pericyst basket-shaped, hypopericyst hemispherical, epipericyst composed of transverse meridional band connected to endocyst by a funnel-like apical projection arising from the endocyst; endocyst subspherical; parasutural features incompletely developed; endoarcheopyle type P 3" only.
Amiculosphaera, Harland, 1979b, p.535.
Type: Harland, 1979b, pl.2, figs.1–3, as Amiculosphaera umbraculum.
---------------------------------------------------------------------------------------------------
Original description: [Harland, 1979]:
Description:
Cavate cyst with an epitractal, cingular and partly hypotractal pericoel formed by the separation of the periphragm from the endophragm. Periphragm forms an outer `cloak-like` covering to the epitract that may or may not carry traces of a paratabulation but which is attached to the hypotract within the post-cingular series. Periphragm supported at the apex by an apical process that is confluent with the periphragm. Tabulation gonyaulacacean, the archeopyle precingular formed by the loss of 3`` in both the endoblast and periblast.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams, 1987, p. 15:
Synopsis:
Cysts proximate, outline subcircular to rhomboidal in dorsal-ventral view, circumcavate; pericyst basket-shaped, hypopericyst hemispherical, epipericyst composed of transverse meridional band connected to endocyst by a funnel-like apical projection arising from the endocyst; endocyst subspherical; parasutural features incompletely developed; endoarcheopyle type P, 3`` only.
Description:
Shape: Pericyst outline in dorsal-ventral view more or less circular to rhomboidal.
Wall relationships: Cysts circumcavate, endocyst subspherical to ovoidal, attached to pericyst antapically, separated elsewhere; pericyst basket- shaped, hypopericyst hemispherical, epipericyst consists of a transverse, meridional band connected apically to a funnel-like structure arising from the apical pole of the endocyst.
Wall features: Periphragm and endophragm smooth; low parasutural ridges may be present.
Paratabulation: Indicated incompletely by discontinuous, low parasutural ridges mainly on the dorsal surface.
Archeopyle: Precingular, type P, 3`` only and present in endophragm only; operculum free.
Paracingulum: Expressed by a discontinuous, low, transverse, equatorial ridge or ridges.
Parasulcus: Apparently not indicated.
Size: Intermediate, up to 80 µm in diameter.
Affinities:
Amiculosphaera differs from Lophocysta Manum 1979 in the structure of the pericyst. In the former, the periphragm contacts the endophragm only in the antapical polar area and seemingly has little or no contact with the periphragm elsewhere, except at the apical pole where it merges with a funnel-like structure. Thus, Amiculosphaera is essentially circumcavate. In contrast, Lophocysta is camocavate with the periphragm appressed to the endophragm dorsally ad separated from it ventrally. In Invertocysta Edwards 1984, the pericyst is bowl-shaped, appressed to the endocyst in the midventral region and has a large dorsal opening. In Thalassiphora Eisenack and Gocht 1960 emended Benedek and Gocht 1981, the periphragm is open ventrally and appressed to the endophragm dorsally.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Amiculosphaera, Harland, 1979b. Stover and Williams (1987, p. 15) gave the following synopsis. Cysts proximate, outline subcircular to rhomboidal in dorsal-ventral view, circumcavate; pericyst basket-shaped, hypopericyst hemispherical, epipericyst composed of transverse meridional band connected to endocyst by a funnel-like apical projection arising from the endocyst; endocyst subspherical; parasutural features incompletely developed; endoarcheopyle type P 3" only.