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Palaeostomocystis
From Williams et al., 2017:
[Palaeostomocystis, Deflandre 1937b, p. 52; Emendations: Deflandre, 1966, p. 6
Acritarch genus, according to Fensome et al., 1990
tax. sr. syn. of Cladopyxidium McLean, 1972, according to Marheinecke, 1992. Lentin and Williams, 1993, retained Cladopyxidium as a separate genus.
Type species: Palaeostomocystis reticulata, Deflandre, 1937b (pl.12 (al. pl.9), fig.4)]
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Original description: [Deflandre, 1937]: (Translation: Stover and Evitt, 1978, p. 69):
Description:
Small cells composed of organic matter, united in this genus, are characterized by the consistent presence of a pore or a more or less large opening. This pore may or may not be provided with a diversely developed collar. The general form of the small cells is variable in the species recorded so far; some are spherical, others ellipsoidal, ovoidal, and certainly other shapes will be found. The surface of the wall may be smooth or ornamented.
The dimensions are always small and in the order of around 10 to 40 µm.
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Emended description:
Deflandre, 1966: (Translation: Stover and Evitt, 1978, p. 69):
Small, ellipsoidal organic cells ornamented with a more or less small mesh network of membranes perpendicular to the surface, forming variable size lumina; cells most generally open at the narrow pole, where at times a sort of low collar is formed.
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Modified description:
Stover and Evitt, 1978, p. 69:
Synopsis:
Cysts ellipsoidal and reticulate, with narrow muri and small lumina that vary in size and shape; archeopyle at apex, type uncertain, may have a thickened rim.
Description:
Shape: Ellipsoidal.
Wall relationships: Autophragm only.
Wall features: Autophragm reticulate; mesh with narrow muri and relatively small lumina, which vary considerably in size and shape; wall and reticulum smooth.
Paratabulation: Not indicated.
Archeopyle: At apex, type uncertain; may have a thickened rim; operculum apparently free.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Small.
Affinities:
Paleostomocystis differs from Fromea in having a reticulate rather than a smooth or faintly ornamented autophragm.
[Palaeostomocystis, Deflandre 1937b, p. 52; Emendations: Deflandre, 1966, p. 6
Acritarch genus, according to Fensome et al., 1990
tax. sr. syn. of Cladopyxidium McLean, 1972, according to Marheinecke, 1992. Lentin and Williams, 1993, retained Cladopyxidium as a separate genus.
Type species: Palaeostomocystis reticulata, Deflandre, 1937b (pl.12 (al. pl.9), fig.4)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Deflandre, 1937]: (Translation: Stover and Evitt, 1978, p. 69):
Description:
Small cells composed of organic matter, united in this genus, are characterized by the consistent presence of a pore or a more or less large opening. This pore may or may not be provided with a diversely developed collar. The general form of the small cells is variable in the species recorded so far; some are spherical, others ellipsoidal, ovoidal, and certainly other shapes will be found. The surface of the wall may be smooth or ornamented.
The dimensions are always small and in the order of around 10 to 40 µm.
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Emended description:
Deflandre, 1966: (Translation: Stover and Evitt, 1978, p. 69):
Small, ellipsoidal organic cells ornamented with a more or less small mesh network of membranes perpendicular to the surface, forming variable size lumina; cells most generally open at the narrow pole, where at times a sort of low collar is formed.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt, 1978, p. 69:
Synopsis:
Cysts ellipsoidal and reticulate, with narrow muri and small lumina that vary in size and shape; archeopyle at apex, type uncertain, may have a thickened rim.
Description:
Shape: Ellipsoidal.
Wall relationships: Autophragm only.
Wall features: Autophragm reticulate; mesh with narrow muri and relatively small lumina, which vary considerably in size and shape; wall and reticulum smooth.
Paratabulation: Not indicated.
Archeopyle: At apex, type uncertain; may have a thickened rim; operculum apparently free.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Small.
Affinities:
Paleostomocystis differs from Fromea in having a reticulate rather than a smooth or faintly ornamented autophragm.