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Impagidinium modicum ssp. denticulatum
Impagidinium modicum ssp. denticulatum (Brideaux, 1977) Jan du Chêne et al., 1986
Originally Leptodinium modicum ssp. denticulatum, subsequently (and now) Impagidinium modicum ssp. denticulatum.
Holotype: Brideaux, 1977, pl.1, figs.10-11
Locus typicus: Richardson Mountains, District of Mackenzie, Canada
Stratum typicum: Barremian
Original diagnosis: Brideaux, 1977, p.8: Leptodinium modicum ssp. denticulatum
Shape: Pericyst nearly equidimensional to slightly longer than broad, the outline subcircular, ovoid, occasionally somewhat pentagonal; apical and antapical horns lacking. Endocyst as above, the two layers closely appressed; no pericoel development; compression dorso-ventral, if any.
Phragma: Periphragm about 1 µm thick, smooth or scabrate, forming parasutural septa up to 5 µm high; the septa entire-margined but with discrete distal marginal spinules 0.5 to 1.5 µm high, or serrate and with or without spinules; occasional intratabular spinules present, up to 1 µm high. Endophragm about 1 µm thick and smooth.
Paratabulation: Periphragm forming parasutural crests denoting a paratabulation of 4", 6", 6c, 5""", ?1p, 1""""; folding of the phragma distorting the shape of the paraplates. Endophragm showing no evidence of paratabulation.
Archeopyle/operculum: Archeopyle formed by the loss of precingular paraplate 3". Operculum simple, free, somewhat horseshoe shaped, slightly longer than broad; the two layers closely appressed and separating as a unit. Formula P.
Pericingulum/perisulcus: Helicoid pericingulum about 5µ wide and displaced one to one and one-half pericingular widths; six cingular paraplates; perisulcal region in places obscured by folding of the phragma, perisulcus extending about halfway onto the epicyst and terminating posteriorly near the antapex, inclined to the left.
Dimensions - Pericyst length, 45-65 µm; pericyst width, 42-57 µm.
Affinities:
Brideaux, 1977, p. 8: Leptodinium modicum ssp. denticulatum
Leptodinium modicum ssp. denticulatum differs from Leptodinium modicum subsp. modicum in the possession of serrate or denticulate parasutural crests.
Originally Leptodinium modicum ssp. denticulatum, subsequently (and now) Impagidinium modicum ssp. denticulatum.
Holotype: Brideaux, 1977, pl.1, figs.10-11
Locus typicus: Richardson Mountains, District of Mackenzie, Canada
Stratum typicum: Barremian
Original diagnosis: Brideaux, 1977, p.8: Leptodinium modicum ssp. denticulatum
Shape: Pericyst nearly equidimensional to slightly longer than broad, the outline subcircular, ovoid, occasionally somewhat pentagonal; apical and antapical horns lacking. Endocyst as above, the two layers closely appressed; no pericoel development; compression dorso-ventral, if any.
Phragma: Periphragm about 1 µm thick, smooth or scabrate, forming parasutural septa up to 5 µm high; the septa entire-margined but with discrete distal marginal spinules 0.5 to 1.5 µm high, or serrate and with or without spinules; occasional intratabular spinules present, up to 1 µm high. Endophragm about 1 µm thick and smooth.
Paratabulation: Periphragm forming parasutural crests denoting a paratabulation of 4", 6", 6c, 5""", ?1p, 1""""; folding of the phragma distorting the shape of the paraplates. Endophragm showing no evidence of paratabulation.
Archeopyle/operculum: Archeopyle formed by the loss of precingular paraplate 3". Operculum simple, free, somewhat horseshoe shaped, slightly longer than broad; the two layers closely appressed and separating as a unit. Formula P.
Pericingulum/perisulcus: Helicoid pericingulum about 5µ wide and displaced one to one and one-half pericingular widths; six cingular paraplates; perisulcal region in places obscured by folding of the phragma, perisulcus extending about halfway onto the epicyst and terminating posteriorly near the antapex, inclined to the left.
Dimensions - Pericyst length, 45-65 µm; pericyst width, 42-57 µm.
Affinities:
Brideaux, 1977, p. 8: Leptodinium modicum ssp. denticulatum
Leptodinium modicum ssp. denticulatum differs from Leptodinium modicum subsp. modicum in the possession of serrate or denticulate parasutural crests.