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Trithyrodinium pentagonum
Trithyrodinium pentagonum May, 1980
Now Pierceites. Originally Trithyrodinium, subsequently (and now) Pierceites.
Holotype: May, 1980, pl.10, figs.13-14
Locus typicus: Atlantic Highlands, New Jersey
Stratum typicum: Maastrichtian
Original description: May, 1980, p.87-88
Cyst single layered autoblast, pentagonal in dorso-ventral outline; dorso-ventrally flattened; tapering apically from cingulum in near linear fashion, deviating at apex to form short, rounded apical horn; tapering antapically from cingulum with slightly concave sides to broadly truncated antapex bearing 2 short antapical horns. Apical horn relatively short (up to 19 µm long), tapering, distally rounded. Left antapical horn relatively short (up to 15 µm long), broadly tapering, V-shaped, blunt-tipped. Right antapical horn short (up to 5 µm long), broad, rounded protrusion. Outline between antapical horns concave and slanting downward to left antapical horn. Autophragm faintly granular to microrugulate; nontabulated. Cingulum slightly levorotatory, ca. 1/2 cingulum width offset, visible mainly dorsally and ventrally, but generally not laterally; formed of 2 parallel folds in autophragm. Sulcus shallow; extends nearly vertically from between terminal ends of cingulum to antapex, intersecting antapex between antapical horns. Archeopyle intercalary (Type 3I); opercular pieces (la, 2a, and 3a plate equivalents) generally in place, but don"t appear attached; 2a plate equivalent hexagonal in outline; la and 3a pentagonal.
Discussion: Characteristic features of T. pentagonum are the pentagonal outline, single wall layer, intercalary archeopyle (Type 3I), and broad blunt antapical processes.
Dimensions: Holotype--L x W, 67 x 49 µm, apical horn length 9 µm, left antapical horn length 8 µm. Observed range (20 specimens measured): length 62-87 µm, width 50-62 µm, apical horn length 9-10 µm, left antapical horn length 2-15 µm, right antapical horn length 3-5 µm. Wall layer, less than 1 µm thick.
Affinities:
May, 1980, p.88: T. pentagonum is dissimilar from T. evittii Drugg 1967 by lacking a distinct endoblast and anterior and posterior pericoels. It is dissimilar from T. fragile Davey 1969 by possessing cingulum and sulcus in some specimens, and in being single layered.
Now Pierceites. Originally Trithyrodinium, subsequently (and now) Pierceites.
Holotype: May, 1980, pl.10, figs.13-14
Locus typicus: Atlantic Highlands, New Jersey
Stratum typicum: Maastrichtian
Original description: May, 1980, p.87-88
Cyst single layered autoblast, pentagonal in dorso-ventral outline; dorso-ventrally flattened; tapering apically from cingulum in near linear fashion, deviating at apex to form short, rounded apical horn; tapering antapically from cingulum with slightly concave sides to broadly truncated antapex bearing 2 short antapical horns. Apical horn relatively short (up to 19 µm long), tapering, distally rounded. Left antapical horn relatively short (up to 15 µm long), broadly tapering, V-shaped, blunt-tipped. Right antapical horn short (up to 5 µm long), broad, rounded protrusion. Outline between antapical horns concave and slanting downward to left antapical horn. Autophragm faintly granular to microrugulate; nontabulated. Cingulum slightly levorotatory, ca. 1/2 cingulum width offset, visible mainly dorsally and ventrally, but generally not laterally; formed of 2 parallel folds in autophragm. Sulcus shallow; extends nearly vertically from between terminal ends of cingulum to antapex, intersecting antapex between antapical horns. Archeopyle intercalary (Type 3I); opercular pieces (la, 2a, and 3a plate equivalents) generally in place, but don"t appear attached; 2a plate equivalent hexagonal in outline; la and 3a pentagonal.
Discussion: Characteristic features of T. pentagonum are the pentagonal outline, single wall layer, intercalary archeopyle (Type 3I), and broad blunt antapical processes.
Dimensions: Holotype--L x W, 67 x 49 µm, apical horn length 9 µm, left antapical horn length 8 µm. Observed range (20 specimens measured): length 62-87 µm, width 50-62 µm, apical horn length 9-10 µm, left antapical horn length 2-15 µm, right antapical horn length 3-5 µm. Wall layer, less than 1 µm thick.
Affinities:
May, 1980, p.88: T. pentagonum is dissimilar from T. evittii Drugg 1967 by lacking a distinct endoblast and anterior and posterior pericoels. It is dissimilar from T. fragile Davey 1969 by possessing cingulum and sulcus in some specimens, and in being single layered.