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Stephanelytron
From Williams et al., 2017:
[Stephanelytron, Sarjeant, 1961a, p. 109; Emendations: Stover et al., 1977, p. 331; Courtinat, 1999, p. 177.
Type species: Stephanelytron redcliffense, Sarjeant, 1961a (pl.15, fig.11; text-fig.10)]
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Original description: [Sarjeant, 1961]:
Description:
Organic shells of spheroidal to oval shape, bearing on one face (at one end in ovoidal forms) one or more structures consisting of a circular membrane rising outwards from the shell surface and inverted, surrounding a matte of short hairs or spines; this structure is henceforth termed a `corona.` Elsewhere the shell bears tubular processes of varied character and arrangement.
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Emended description:
Stover et al., 1977:
Description:
Cysts proximochorate with a subspherical to ellipsoidal body composed of two wall layers. Inner wall, the autophragm, gives rise to usually short processes; outer wall, the ectophragm, thin and may be discontinuous. Processes frequently arranged in parasutural rows, less commonly nontabular, and some forms have parasutural and scattered nontabular processes, penitabular processes present on one species. Processes cylindrical to tubiform normally of uniform height or nearly so, but width may vary considerably.
Paratabulation indicated by alignment of processes on some species, formula: 1`?, 5", X4c, 5```,1````, 2s.
Archeopyle apical, operculum free, rarely adherent, exact archeopyle shape and number of paraplates in operculum are uncertain; antapical area with typically one or occasionally two coronas.
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Modified description:
Stover and Evitt, 1978, p. 82:
Synopsis:
Cysts proximochorate, subspherical to ellipsoidal; holocavate except at antapical pole; autophragm separated from ectophragm by short tubular processes; processes nontabular, penitabular, intratabular, or combination thereof; body with one or, rarely, two antapical coronas; paratabulation gonyaulacacean, archeopyle apical.
Description:
Shape: Subspherical to ellipsoidal.
Wall relationships: Cysts holocavate except at antapical pole; ectophragm thin, may be incomplete.
Wall features: Processes parasutural, penitabular, or nontabular; short, tubular, usually expanded distally, of approximately uniform height, and with smooth or punctate walls. Autophragm smooth generally with a well developed antapical corona, or rarely with two coronas.
Paratabulation: Indicated by parasutural and/or penitabular arrangement of processes; gonyaulacacean, formula: 1 or4`, 5", Xc, 5```, o-1p 1````, 1-2s.
Archeopyle: Apical, type uncertain; operculum generally free and may have a single process that tends to be slightly larger than others on the rest of the cyst. Exact shape of operculum unknown, as is the trace of the archeopyle.
Paracingulum: Indicated by single or double transverse rows of processes; rarely discernible on forms with mostly nontabular processes.
Parasulcus: Not indicated.
Size: Small to intermediate.
Affinities:
Stephanelytron differs from other dinoflagellate cysts in having a corona, or occasionally two coronas, at the antapical end.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Stephanelytron Sarjeant, 1961a, emend. Stover et al., 1977. Stover et al. (1977, p.331) emended the diagnosis thus. Cysts proximochorate with subspherical to ellipsoidal body composed of two wall layers. Inner wall, the autophragm, gives rise to usually short processes; outer wall, the ectophragm, thin and may be discontinuous. Processes frequently arranged in parasutural rows, less commonly nontabular; some forms have parasutural and scattered nontabular processes, penitabular processes being present on one species. Processes cylindrical to tubiform, normally of uniform height or nearly so, but width may vary considerably. Paratabulation indicated by alignment of processes on some species, formula: 1`?, 5", x-6c, 5```, 0-1p, 1```` , 2s. Archeopyle apical, operculum free, rarely attached; exact archeopyle shape and number of paraplates in operculum uncertain; antapical area typically with one or occasionally with two coronas.
[Stephanelytron, Sarjeant, 1961a, p. 109; Emendations: Stover et al., 1977, p. 331; Courtinat, 1999, p. 177.
Type species: Stephanelytron redcliffense, Sarjeant, 1961a (pl.15, fig.11; text-fig.10)]
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Original description: [Sarjeant, 1961]:
Description:
Organic shells of spheroidal to oval shape, bearing on one face (at one end in ovoidal forms) one or more structures consisting of a circular membrane rising outwards from the shell surface and inverted, surrounding a matte of short hairs or spines; this structure is henceforth termed a `corona.` Elsewhere the shell bears tubular processes of varied character and arrangement.
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Emended description:
Stover et al., 1977:
Description:
Cysts proximochorate with a subspherical to ellipsoidal body composed of two wall layers. Inner wall, the autophragm, gives rise to usually short processes; outer wall, the ectophragm, thin and may be discontinuous. Processes frequently arranged in parasutural rows, less commonly nontabular, and some forms have parasutural and scattered nontabular processes, penitabular processes present on one species. Processes cylindrical to tubiform normally of uniform height or nearly so, but width may vary considerably.
Paratabulation indicated by alignment of processes on some species, formula: 1`?, 5", X4c, 5```,1````, 2s.
Archeopyle apical, operculum free, rarely adherent, exact archeopyle shape and number of paraplates in operculum are uncertain; antapical area with typically one or occasionally two coronas.
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Modified description:
Stover and Evitt, 1978, p. 82:
Synopsis:
Cysts proximochorate, subspherical to ellipsoidal; holocavate except at antapical pole; autophragm separated from ectophragm by short tubular processes; processes nontabular, penitabular, intratabular, or combination thereof; body with one or, rarely, two antapical coronas; paratabulation gonyaulacacean, archeopyle apical.
Description:
Shape: Subspherical to ellipsoidal.
Wall relationships: Cysts holocavate except at antapical pole; ectophragm thin, may be incomplete.
Wall features: Processes parasutural, penitabular, or nontabular; short, tubular, usually expanded distally, of approximately uniform height, and with smooth or punctate walls. Autophragm smooth generally with a well developed antapical corona, or rarely with two coronas.
Paratabulation: Indicated by parasutural and/or penitabular arrangement of processes; gonyaulacacean, formula: 1 or4`, 5", Xc, 5```, o-1p 1````, 1-2s.
Archeopyle: Apical, type uncertain; operculum generally free and may have a single process that tends to be slightly larger than others on the rest of the cyst. Exact shape of operculum unknown, as is the trace of the archeopyle.
Paracingulum: Indicated by single or double transverse rows of processes; rarely discernible on forms with mostly nontabular processes.
Parasulcus: Not indicated.
Size: Small to intermediate.
Affinities:
Stephanelytron differs from other dinoflagellate cysts in having a corona, or occasionally two coronas, at the antapical end.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Stephanelytron Sarjeant, 1961a, emend. Stover et al., 1977. Stover et al. (1977, p.331) emended the diagnosis thus. Cysts proximochorate with subspherical to ellipsoidal body composed of two wall layers. Inner wall, the autophragm, gives rise to usually short processes; outer wall, the ectophragm, thin and may be discontinuous. Processes frequently arranged in parasutural rows, less commonly nontabular; some forms have parasutural and scattered nontabular processes, penitabular processes being present on one species. Processes cylindrical to tubiform, normally of uniform height or nearly so, but width may vary considerably. Paratabulation indicated by alignment of processes on some species, formula: 1`?, 5", x-6c, 5```, 0-1p, 1```` , 2s. Archeopyle apical, operculum free, rarely attached; exact archeopyle shape and number of paraplates in operculum uncertain; antapical area typically with one or occasionally with two coronas.