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Rottnestia
From Williams et al., 2017:
[Rottnestia, Cookson and Eisenack, 1961b, p. 40, 42.
Tax. sr. syn.: Hystrichosphaeropsis, according to Sarjeant (1966b, p.139) — however, Stover and Evitt (1978, p.185) retained Rottnestia; Triblastula, according to Yun Hyesu (1981, p.22) — however, Jan du Chêne et al. (1986a, p.309) retained Rottnestia.
Type species: Hystrichosphaera borussica, Eisenack, 1954b (pl.9, fig.5)]
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Original description: [Cookson and Eisenack, 1961]:
Description:
The shell consists, like those of a number of fossil dinoflagellates, of an internal body and a thin outer membrane. The internal body is clearly an oval in shape. The outer membrane is in contact with the internal body in the central region but extends beyond it apically and antapically. The apical expansion is surmounted by a median conical or cylindrical horn; the antapical expansion is squarish in shape with sharp to rounded angles. The shell is crossed by a median helicoid girdle and a relatively broad longitudinal furrow runs obliquely across the ventral surface. The surface of the outer membrane is divided into the pre- and post-equatorial fields the limits of which run into the edges supporting the apical and antapical expansions. Forked appendages may or may not be developed at the corners of the fields. A large elongate-trapezoid pylome develops on the dorsal side of the epitheca in both the internal body and outer membrane.
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Modified description:
(Jan du Chêne et al. (1986a, p.309) referred to the description of this genus by Stover and Evitt (1978, p.185) as an emendation, although the latter authors did not indicate it to be an emendation. )
Stover and Evit, 1978, p. 185:
Synopsis:
Cysts bicavate, elongate ellipsoidal, with an apical horn; endocyst ellipsoidal to ovoidal; paratabulation gonyaulacacean, indicated by smooth parasutural ridges and by typically short gonal processes at some of the paraplate junctures; archaeopyle precingular, Type P.
Description:
Shape: Elongate ellipsoidal with an apical horn and, usually, a truncated antapical end.
Wall relationships: Cysts bicavate; endocyst ellipsoidal to ovoidal; apical and antapical pericoels moderately to well developed.
Wall features: Low smooth parasutural ridges on all or part of periphragm; typically short gonal processes with triffurcate tips present at intersections of some parasutures.
Paratabulation: Indicated by parasutural ridges and reinforced in part by gonal processes; gonyaulacacean, formula: 3-4`?, 6``, 6c, 5-6```, 1p, 1````. Paratabulation in apical area often undecipherable.
Archaeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Indicated by six rectangular to subrectangular paraplates; ventral ends generally strongly offset.
Parasulcus: Generally delimited by parasutural features, but margins may be poorly defined on hypocyst.
Size: Intermediate to large.
Affinities:
Rottnestia differs from Hystrichosphaeropsis and Psaligonyaulax in possessing gonal processes, which are lacking on the other two genera.
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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.
Rottnestia Cookson and Eisenack, 1961b. Synopsis from Stover and Evitt (1978), Cysts bicavate, elongate ellipsoidal, with an apical horn; endocyst ellipsoidal to ovoidal; paratabulation gonyaulacacean, indicated by smooth parasutural ridges and by typically short gonal processes at some of the paraplate junctions; archeopyle precingular, type P.
[Rottnestia, Cookson and Eisenack, 1961b, p. 40, 42.
Tax. sr. syn.: Hystrichosphaeropsis, according to Sarjeant (1966b, p.139) — however, Stover and Evitt (1978, p.185) retained Rottnestia; Triblastula, according to Yun Hyesu (1981, p.22) — however, Jan du Chêne et al. (1986a, p.309) retained Rottnestia.
Type species: Hystrichosphaera borussica, Eisenack, 1954b (pl.9, fig.5)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Cookson and Eisenack, 1961]:
Description:
The shell consists, like those of a number of fossil dinoflagellates, of an internal body and a thin outer membrane. The internal body is clearly an oval in shape. The outer membrane is in contact with the internal body in the central region but extends beyond it apically and antapically. The apical expansion is surmounted by a median conical or cylindrical horn; the antapical expansion is squarish in shape with sharp to rounded angles. The shell is crossed by a median helicoid girdle and a relatively broad longitudinal furrow runs obliquely across the ventral surface. The surface of the outer membrane is divided into the pre- and post-equatorial fields the limits of which run into the edges supporting the apical and antapical expansions. Forked appendages may or may not be developed at the corners of the fields. A large elongate-trapezoid pylome develops on the dorsal side of the epitheca in both the internal body and outer membrane.
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Modified description:
(Jan du Chêne et al. (1986a, p.309) referred to the description of this genus by Stover and Evitt (1978, p.185) as an emendation, although the latter authors did not indicate it to be an emendation. )
Stover and Evit, 1978, p. 185:
Synopsis:
Cysts bicavate, elongate ellipsoidal, with an apical horn; endocyst ellipsoidal to ovoidal; paratabulation gonyaulacacean, indicated by smooth parasutural ridges and by typically short gonal processes at some of the paraplate junctures; archaeopyle precingular, Type P.
Description:
Shape: Elongate ellipsoidal with an apical horn and, usually, a truncated antapical end.
Wall relationships: Cysts bicavate; endocyst ellipsoidal to ovoidal; apical and antapical pericoels moderately to well developed.
Wall features: Low smooth parasutural ridges on all or part of periphragm; typically short gonal processes with triffurcate tips present at intersections of some parasutures.
Paratabulation: Indicated by parasutural ridges and reinforced in part by gonal processes; gonyaulacacean, formula: 3-4`?, 6``, 6c, 5-6```, 1p, 1````. Paratabulation in apical area often undecipherable.
Archaeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Indicated by six rectangular to subrectangular paraplates; ventral ends generally strongly offset.
Parasulcus: Generally delimited by parasutural features, but margins may be poorly defined on hypocyst.
Size: Intermediate to large.
Affinities:
Rottnestia differs from Hystrichosphaeropsis and Psaligonyaulax in possessing gonal processes, which are lacking on the other two genera.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Rottnestia Cookson and Eisenack, 1961b. Synopsis from Stover and Evitt (1978), Cysts bicavate, elongate ellipsoidal, with an apical horn; endocyst ellipsoidal to ovoidal; paratabulation gonyaulacacean, indicated by smooth parasutural ridges and by typically short gonal processes at some of the paraplate junctions; archeopyle precingular, type P.