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Homotryblium
From Williams et al., 2017:
[Homotryblium, Davey and Williams, 1966b, p. 100
Type species: Homotryblium tenuispinosum, Davey and Williams, 1966b (pl.12, fig.5)]
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Original description: [Davey and Williams, 1966]:
Diagnosis:
Subspherical chorate cyst with central body composed of thin endophragm and surrounding periphragm which gives rise to processes.
Processes intratabular, cylindrical to tubiform, open distally, reflecting a tabulation of 3`, 6``, 6c, 6```, 1p, 1```` and 1-5s. Processes not in communication with cavity of the central body.
Archaeopyle epitractal, suture running just above cingulum processes.
Description:
The genus Homotryblium is unusual in possessing an epitractal archaeopyle which has a compound operculum composed of the apical and precingular plate series. It is an easily recognizable genus because of the nature of this archaeopyle the possession of only 3 apical processes. Dinoflagellate cysts possessing epitractal archaeopyles are rare. Rhaetogonyaulax and Dichadogonyaulax are both described by Sarjeant, as possessing epitractal archaeopyles.
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Modified description:
Stover and Evitt 1978, p. 210:
Synopsis:
Cysts skolochorate, acavate; body subspherical with about 25 normally tubular intratabular processes; paratabulation gonyaulacacean, indicated on epicyst by processes and opercular pieces, on rest of cyst by processes only; combination archeopyle, Type A+3A+6P.
Description:
Shape: Body subspherical; isolated hypocysts commonly seen in apical- antapical orientation.
Wall relationships: Cysts acavate; endophragm and periphragm appressed between processes.
Wall features: No parasutural features on hypocyst; on epicyst, opercular pieces separate along paraplate boundaries. Intratabular processes hollow, open, and generally expanded distally; each process consists of one or more tubes. Periphragm between processes smooth, scabrate, or granular.
Paratabulation: Indicated on epicyst by intratabular processes, archeopyle sutures, and opercular pieces, and on hypocyst by intratabular processes only; gonyaulacacean, formula: 0-1pr, 4`, 6``, 6c, 5-6```, 1p, 1````, 2+s. When five postcingular processes are present they are interpreted as representing plates 2```, to 6```.
Archeopyle: Combination archeopyle, Type A+3A+6P; principal archeopyle suture straight along apical margin of paracingulum except at midventral surface, where it follows the outline of the parasulcal tab and the shallow depression on its right side. Parasulcal tab corresponds to high position of anterior sulcal paraplate; the depression corresponds to low position of paraplate 6``. Six precingular and first apical paraplates separate individually; apical paraplates 2` and 4`, although separated from the other seven opercular pieces, remain together; operculum free.
Paracingulum: Indicated by six processes and by archeopyle margin.
Parasulcus: Position indicated by parasulcal tab and two or more parasulcal processes.
Size: Intermediate to large.
Affinities:
Homotryblium differs from Hemicystodinium and Eocladopyxis, which also have a combination Type A+3A+6P archeopyle, in having intratabular rather than nontabular processes. Hystrichosphaeridium, which has intratabular processes like those of Homotryblium, possesses an apical archeopyle.
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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.
Homotryblium Davey and Williams, 1966b. Synopsis from Stover and Evitt (1978, p.210), cysts skolochorate, acavate; body subspherical with about 25 normally tubular intratabular processes; paratabulation gonyaulacacean, indicated on epicyst by processes and opercular pieces, on rest of cyst by processes only; combination archeopyle, type A + (3A) + 6P. 1` metasert.
[Homotryblium, Davey and Williams, 1966b, p. 100
Type species: Homotryblium tenuispinosum, Davey and Williams, 1966b (pl.12, fig.5)]
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Original description: [Davey and Williams, 1966]:
Diagnosis:
Subspherical chorate cyst with central body composed of thin endophragm and surrounding periphragm which gives rise to processes.
Processes intratabular, cylindrical to tubiform, open distally, reflecting a tabulation of 3`, 6``, 6c, 6```, 1p, 1```` and 1-5s. Processes not in communication with cavity of the central body.
Archaeopyle epitractal, suture running just above cingulum processes.
Description:
The genus Homotryblium is unusual in possessing an epitractal archaeopyle which has a compound operculum composed of the apical and precingular plate series. It is an easily recognizable genus because of the nature of this archaeopyle the possession of only 3 apical processes. Dinoflagellate cysts possessing epitractal archaeopyles are rare. Rhaetogonyaulax and Dichadogonyaulax are both described by Sarjeant, as possessing epitractal archaeopyles.
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Modified description:
Stover and Evitt 1978, p. 210:
Synopsis:
Cysts skolochorate, acavate; body subspherical with about 25 normally tubular intratabular processes; paratabulation gonyaulacacean, indicated on epicyst by processes and opercular pieces, on rest of cyst by processes only; combination archeopyle, Type A+3A+6P.
Description:
Shape: Body subspherical; isolated hypocysts commonly seen in apical- antapical orientation.
Wall relationships: Cysts acavate; endophragm and periphragm appressed between processes.
Wall features: No parasutural features on hypocyst; on epicyst, opercular pieces separate along paraplate boundaries. Intratabular processes hollow, open, and generally expanded distally; each process consists of one or more tubes. Periphragm between processes smooth, scabrate, or granular.
Paratabulation: Indicated on epicyst by intratabular processes, archeopyle sutures, and opercular pieces, and on hypocyst by intratabular processes only; gonyaulacacean, formula: 0-1pr, 4`, 6``, 6c, 5-6```, 1p, 1````, 2+s. When five postcingular processes are present they are interpreted as representing plates 2```, to 6```.
Archeopyle: Combination archeopyle, Type A+3A+6P; principal archeopyle suture straight along apical margin of paracingulum except at midventral surface, where it follows the outline of the parasulcal tab and the shallow depression on its right side. Parasulcal tab corresponds to high position of anterior sulcal paraplate; the depression corresponds to low position of paraplate 6``. Six precingular and first apical paraplates separate individually; apical paraplates 2` and 4`, although separated from the other seven opercular pieces, remain together; operculum free.
Paracingulum: Indicated by six processes and by archeopyle margin.
Parasulcus: Position indicated by parasulcal tab and two or more parasulcal processes.
Size: Intermediate to large.
Affinities:
Homotryblium differs from Hemicystodinium and Eocladopyxis, which also have a combination Type A+3A+6P archeopyle, in having intratabular rather than nontabular processes. Hystrichosphaeridium, which has intratabular processes like those of Homotryblium, possesses an apical archeopyle.
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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.
Homotryblium Davey and Williams, 1966b. Synopsis from Stover and Evitt (1978, p.210), cysts skolochorate, acavate; body subspherical with about 25 normally tubular intratabular processes; paratabulation gonyaulacacean, indicated on epicyst by processes and opercular pieces, on rest of cyst by processes only; combination archeopyle, type A + (3A) + 6P. 1` metasert.