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Impagidinium californiense
Impagidinium californiense Damassa, 1979
Holotype: Damassa, 1979, pl.5, fig.3-6; Jan du Chene et al., 1986, pl.52, fig.18
Paratype: Damassa, 1979
Locus typicus: Costal Belt, Franciscan Complex, California, USA
Stratum typicum: Early-Middle Eocene
Original diagnosis: Damassa, 1979, p. 829-830
Cyst conspicuously spherical. septa low but prominent. Delineation of paratabulation variable in apical and sulcal regions. Archeopvle slightly reduced. rounded pentagonal.
Original description: Damassa, 1979, p. 830
Cyst spherical. 77-100 µm in diameter (mean = 88µm, holotype = 90µm, 12 specimens measured), characterized by low but prominent parasutural septa. Autophragm about 2 µm thick. elevated to form thin, translucent septa, with slightly irregular edges, 36 µm in height. Surface of cyst appears smooth at magnifications up to approximately 1000x, but appears rugulate at higher magnifications. Septum between the first and fourth apical paraplates may be lacking, or partially to completely developed. In some specimens a preapical paraplate is indicated. Parasulcal septa highly variable in development! but generally septa at least partially delineate 1""", rs, ras, and ls. The anterior sulcal paraplate also may be expressed by a short extension of septa into the parasulcus from either side. Archeopvle precingular, reduced, outline often rounded and slightly irregular. Ends of paracingulum offset a distance approximately equal to width at left side of parasulcus. Width of paracingulum greater on left side than on right side of parasulcus. Paratabulation. - ?pr, 3-4", 6", 6c, 4-5s, 1p, 6""", 1"""". Inferred thecal tabulation. -1pr, 4", 6", 6c, 5s, 1p, 6""", 1"""".
Affinities:
Damassa, 1979, p. 830: Impagidinium californiense is similar in overall size and shape to I. victorianum (Cookson & Eisenack) Stover & Evitt, 1978. However, I. victorianum lacks the septa between the first and sixth cingular paraplates and adjacent postcingulars. Septa are also differently developed in the sulcal region, the anterior and posterior sulcal paraplates being defined by septa, whereas the remainder of the parasulcus is undifferentiated (Cookson & Eisenack, 1965, p. 123). In contrast, I. californiense has complete paracingular septa as well as at least portions of the septa which delineate the smaller sulcal paraplates. I. californiense may be distinguished readily from I. maculatum (Cookson & Eisenack) Stover & Evitt, 1978 by its lack of a distinctly granulate wall texture. Although the surface of I. californiense appears smooth at magnifications up to 1000x, at high magnifications as seen in SEM the wall is distinctly rugulate (PI. 5, fig. 13).
The apical and sulcal regions are variable in I. californiense, as shown in Pl. 5, figs. 49, and Text-fig. 8. The presence of a preapical plate in the thecate stage of I. californiense seems probable, based on the configuration of the apical paraplates and the partial development of a preapical paraplate in some specimens. The septa which delineate the right sulcal paraplate are consistently developed, and may assist in identifying this species.
Holotype: Damassa, 1979, pl.5, fig.3-6; Jan du Chene et al., 1986, pl.52, fig.18
Paratype: Damassa, 1979
Locus typicus: Costal Belt, Franciscan Complex, California, USA
Stratum typicum: Early-Middle Eocene
Original diagnosis: Damassa, 1979, p. 829-830
Cyst conspicuously spherical. septa low but prominent. Delineation of paratabulation variable in apical and sulcal regions. Archeopvle slightly reduced. rounded pentagonal.
Original description: Damassa, 1979, p. 830
Cyst spherical. 77-100 µm in diameter (mean = 88µm, holotype = 90µm, 12 specimens measured), characterized by low but prominent parasutural septa. Autophragm about 2 µm thick. elevated to form thin, translucent septa, with slightly irregular edges, 36 µm in height. Surface of cyst appears smooth at magnifications up to approximately 1000x, but appears rugulate at higher magnifications. Septum between the first and fourth apical paraplates may be lacking, or partially to completely developed. In some specimens a preapical paraplate is indicated. Parasulcal septa highly variable in development! but generally septa at least partially delineate 1""", rs, ras, and ls. The anterior sulcal paraplate also may be expressed by a short extension of septa into the parasulcus from either side. Archeopvle precingular, reduced, outline often rounded and slightly irregular. Ends of paracingulum offset a distance approximately equal to width at left side of parasulcus. Width of paracingulum greater on left side than on right side of parasulcus. Paratabulation. - ?pr, 3-4", 6", 6c, 4-5s, 1p, 6""", 1"""". Inferred thecal tabulation. -1pr, 4", 6", 6c, 5s, 1p, 6""", 1"""".
Affinities:
Damassa, 1979, p. 830: Impagidinium californiense is similar in overall size and shape to I. victorianum (Cookson & Eisenack) Stover & Evitt, 1978. However, I. victorianum lacks the septa between the first and sixth cingular paraplates and adjacent postcingulars. Septa are also differently developed in the sulcal region, the anterior and posterior sulcal paraplates being defined by septa, whereas the remainder of the parasulcus is undifferentiated (Cookson & Eisenack, 1965, p. 123). In contrast, I. californiense has complete paracingular septa as well as at least portions of the septa which delineate the smaller sulcal paraplates. I. californiense may be distinguished readily from I. maculatum (Cookson & Eisenack) Stover & Evitt, 1978 by its lack of a distinctly granulate wall texture. Although the surface of I. californiense appears smooth at magnifications up to 1000x, at high magnifications as seen in SEM the wall is distinctly rugulate (PI. 5, fig. 13).
The apical and sulcal regions are variable in I. californiense, as shown in Pl. 5, figs. 49, and Text-fig. 8. The presence of a preapical plate in the thecate stage of I. californiense seems probable, based on the configuration of the apical paraplates and the partial development of a preapical paraplate in some specimens. The septa which delineate the right sulcal paraplate are consistently developed, and may assist in identifying this species.