Back
Sirmiodiniopsis
From Williams et al., 2017:
[Sirmiodiniopsis, Drugg, 1978, p.73
Type species: Sirmiodiniopsis orbis, Drugg, 1978 (pl.7, fig.11)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Drugg, 1978]:
Diagnosis:
Cyst subcircular in outline and dorsoventrally flattened. Endocyst more or less circular in outline. The archaeopyle is apical and the operculum does not tend to remain attached. Paracingulum and parasulcus developed on the periphragm. Additional paratabulation present but obscure. Two fairly large openings are present on the periphragm, on each side of the antapex.
Affinities:
Sirmiodiniopsis closely resembles Sirmiodinium Alberti 1961. It differs primarily in possessing two antapical openings rather than one. It also differs in that the operculum tends to separate completely whereas in Sirmiodinium the operculum tends to remain attached. In the Sirmiodinium both apical and precingular paraplates are involved in archaeopyle formation. In Sirmiodiniopsis only apical paraplates are involved in archaeopyle formation.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams 1987, p. 199:
Synopsis:
Cyst proximate, lenticular, circumcavate with the amount of separation between the endocyst and pericyst significantly greater on the hypocyst than on the epicyst. Two relatively large openings, one on each side of the antapex, occur in the periphragm, additional openings may be present. Paratabulation indicated by the type [tA] apical archaeopyle and paracingulum; other indications normally obscure except for parasulcal notch.
Description:
Shape: Lenticular, outline subcircular.
Wall relationships: Circumcavate; amount of lateral separation between endocyst and pericyst significantly greater on hypocyst than on epicyst.
Wall features: No parasutural features. Two relatively large, more or less elliptical, ventral openings - one on each side of the antapex - present in periphragm; additional openings may be present. Wall layers smooth or faintly ornamented.
Archaeopyle: Apical, type [tA]; operculum generally free, occasionally adnate ventrally; accessory sutures may partly separate precingular paraplates longitudinally.
Paratabulation: Indicated by archaeopyle and paracingulum; other indications normally obscure or absent.
Paracingulum: indicated by two, parallel, low transverse ridges; not divided longitudinally and ventral ends not strongly offset.
Parasulcus: Anterior position indicated by parasulcal notch; other expressions faint or lacking.
Size: Small to intermediate, about 45 μm to 65 μm in diameter.
Affinities:
Sirmiodiniopsis differs from Sirmiodinium Alberti, 1961 emend. Warren ,1973 in having two or more antapical openings rather than just one opening. In addition, Sirmiodiniopsis lacks the pandasutural features frequently seen on Sirmiodinium and never possesses a [4A](a)+P(a) archaeopyle.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Simiodiniopsis Drugg, 1978. Synopsis from Stover and Williams (1987, p.199), cysts proximate, lenticular, circumcavate with the amount of separation between the endocyst and pericyst significantly greater on the hypocyst than on the epicyst. Two relatively large openings, one on each side of the antapex, occur in the periphragm, additional openings may be present. Paratabulation indicated by the type [tA] apical archeopyle and paracingulum; other indications normally obscure except for parasulcal notch.
[Sirmiodiniopsis, Drugg, 1978, p.73
Type species: Sirmiodiniopsis orbis, Drugg, 1978 (pl.7, fig.11)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Drugg, 1978]:
Diagnosis:
Cyst subcircular in outline and dorsoventrally flattened. Endocyst more or less circular in outline. The archaeopyle is apical and the operculum does not tend to remain attached. Paracingulum and parasulcus developed on the periphragm. Additional paratabulation present but obscure. Two fairly large openings are present on the periphragm, on each side of the antapex.
Affinities:
Sirmiodiniopsis closely resembles Sirmiodinium Alberti 1961. It differs primarily in possessing two antapical openings rather than one. It also differs in that the operculum tends to separate completely whereas in Sirmiodinium the operculum tends to remain attached. In the Sirmiodinium both apical and precingular paraplates are involved in archaeopyle formation. In Sirmiodiniopsis only apical paraplates are involved in archaeopyle formation.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams 1987, p. 199:
Synopsis:
Cyst proximate, lenticular, circumcavate with the amount of separation between the endocyst and pericyst significantly greater on the hypocyst than on the epicyst. Two relatively large openings, one on each side of the antapex, occur in the periphragm, additional openings may be present. Paratabulation indicated by the type [tA] apical archaeopyle and paracingulum; other indications normally obscure except for parasulcal notch.
Description:
Shape: Lenticular, outline subcircular.
Wall relationships: Circumcavate; amount of lateral separation between endocyst and pericyst significantly greater on hypocyst than on epicyst.
Wall features: No parasutural features. Two relatively large, more or less elliptical, ventral openings - one on each side of the antapex - present in periphragm; additional openings may be present. Wall layers smooth or faintly ornamented.
Archaeopyle: Apical, type [tA]; operculum generally free, occasionally adnate ventrally; accessory sutures may partly separate precingular paraplates longitudinally.
Paratabulation: Indicated by archaeopyle and paracingulum; other indications normally obscure or absent.
Paracingulum: indicated by two, parallel, low transverse ridges; not divided longitudinally and ventral ends not strongly offset.
Parasulcus: Anterior position indicated by parasulcal notch; other expressions faint or lacking.
Size: Small to intermediate, about 45 μm to 65 μm in diameter.
Affinities:
Sirmiodiniopsis differs from Sirmiodinium Alberti, 1961 emend. Warren ,1973 in having two or more antapical openings rather than just one opening. In addition, Sirmiodiniopsis lacks the pandasutural features frequently seen on Sirmiodinium and never possesses a [4A](a)+P(a) archaeopyle.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Simiodiniopsis Drugg, 1978. Synopsis from Stover and Williams (1987, p.199), cysts proximate, lenticular, circumcavate with the amount of separation between the endocyst and pericyst significantly greater on the hypocyst than on the epicyst. Two relatively large openings, one on each side of the antapex, occur in the periphragm, additional openings may be present. Paratabulation indicated by the type [tA] apical archeopyle and paracingulum; other indications normally obscure except for parasulcal notch.