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Selenopemphix prionota
Selenopemphix prionota Levy and Harwood, 2000, p.216, pl.8, figs.k–l.
Holotype: Levy and Harwood, 2000, pl.8, fig.k.
Age: middle-late Eocene.
Original description (Levy and Harwood, 2000)
Derivation of name. Greek, prionota, jagged, serrated, in reference to the crenulate to echinate paracingular frill.
Holotype. Plate 8, Figure k. UNSM PB99-05: Sample E 214, slide 5, middle to upper Eocene erratic, McMurdo Sound, Antarctica.
Description. Shape. A peridinioid dinoflagellate cyst that is compressed along its polar axis. In polar view Selenopemphix prionota has an elliptical shape (because of compression along the polar axis, specimens are typically observed in polar view). In equatorial view the cyst has a polygonal shape. The lateral margins of the epicyst are straight and converge toward the apex where a short, blunt apical horn occurs. The hypocyst consists of two rounded to pointed antapical projections.
Paratabulation. Indicated by an intercalary archeopyle and paracingular frill.
Phragma. Smooth thin autophragm.
Paracingulum. Indicated by a broad equatorial region and a paracingular frill. The paracingular region is circumscribed with a broad frill that possesses echinate to crenellate sculpture along its distal margin.
Parasulcus. Indicated in polar view by a concave section in the equatorial margin of the hypocyst and in equatorial view by a longitudinal break in the paracingulum. Archeopyle. The archeopyle appears to be an intercalary type la. However, in many specimens the thin autophragm is broken or tom, and as a result, the position
of the archeopyle is obscured.
Dimensions. One specimen measured: dorso-ventral width - 30μm, lateral width - 36μm.
Comments/comparison. This species is similar to Selenopemphix nephroides but differs in that it possesses a crenulate to echinate paracingular frill. Selenopemphix prionota is similar to Selenopemphix sp. 5 of Head and
Norris (1989) and may be conspecific. S. prionota differs from S. coronata (Bujak in Bujak et al., 1980) and S. brevispinosa (Head et al., 1989) by lacking distal bifurcation or expansion on the spines that surround the paracingulum. Selenopemphix prionota is a rare taxon in the McMurdo Erratics. Stratigraphic Occurrence. Middle to upper Eocene erratics, McMurdo Sound, Antarctica.
Holotype: Levy and Harwood, 2000, pl.8, fig.k.
Age: middle-late Eocene.
Original description (Levy and Harwood, 2000)
Derivation of name. Greek, prionota, jagged, serrated, in reference to the crenulate to echinate paracingular frill.
Holotype. Plate 8, Figure k. UNSM PB99-05: Sample E 214, slide 5, middle to upper Eocene erratic, McMurdo Sound, Antarctica.
Description. Shape. A peridinioid dinoflagellate cyst that is compressed along its polar axis. In polar view Selenopemphix prionota has an elliptical shape (because of compression along the polar axis, specimens are typically observed in polar view). In equatorial view the cyst has a polygonal shape. The lateral margins of the epicyst are straight and converge toward the apex where a short, blunt apical horn occurs. The hypocyst consists of two rounded to pointed antapical projections.
Paratabulation. Indicated by an intercalary archeopyle and paracingular frill.
Phragma. Smooth thin autophragm.
Paracingulum. Indicated by a broad equatorial region and a paracingular frill. The paracingular region is circumscribed with a broad frill that possesses echinate to crenellate sculpture along its distal margin.
Parasulcus. Indicated in polar view by a concave section in the equatorial margin of the hypocyst and in equatorial view by a longitudinal break in the paracingulum. Archeopyle. The archeopyle appears to be an intercalary type la. However, in many specimens the thin autophragm is broken or tom, and as a result, the position
of the archeopyle is obscured.
Dimensions. One specimen measured: dorso-ventral width - 30μm, lateral width - 36μm.
Comments/comparison. This species is similar to Selenopemphix nephroides but differs in that it possesses a crenulate to echinate paracingular frill. Selenopemphix prionota is similar to Selenopemphix sp. 5 of Head and
Norris (1989) and may be conspecific. S. prionota differs from S. coronata (Bujak in Bujak et al., 1980) and S. brevispinosa (Head et al., 1989) by lacking distal bifurcation or expansion on the spines that surround the paracingulum. Selenopemphix prionota is a rare taxon in the McMurdo Erratics. Stratigraphic Occurrence. Middle to upper Eocene erratics, McMurdo Sound, Antarctica.