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Trithyrodinium evittii
From Fensome et al., 2019:
Trithyrodinium evittii Drugg, 1967, p.20, pl.3, figs.2–3; pl.9, fig.2.
Holotype: Drugg, 1967, pl.3, fig.2.
Taxonomic junior synonym: Trithyrodinium fragile, according to Nøhr-Hansen and Dam (1999, p.129).
Locus typicus: Escarpado Canyon, California
Stratum typicum: Danian
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Original diagnosis: Drugg, 1967, p.20
Similar in morphology to members of the genus Deflandrea except that the archeopyle operculum is composed of three intercalary plates functioning as a unit (see pl. 9 fig. 2). Test rounded with one short apical and two short antapical horns. The test wall is thin and smooth. The test cavity is filled by a large rounded cyst of fairly rigid construction. The cyst wall is about 1 µm thick and often finely punctate. The cysts are commonly found separated from the tests in which case they are easily identifiable by the peculiar nature of the opening. A circular girdle is present on the test and is delineated by low flanges. A longitudinal furrow is suggested by folds originating near the antapical horns. The length of the test ranges from 75 to 95 µm and the width ranges from 60 to 80 µm.
Affinities:
Drugg, 1967, p.20: The forms Deflandrea thomasi Cookson and Eisenack 1961, D. granulifera Manum 1963, D. verrucosa Manum 1963, and Hexagonifera suspecta Manum and Cookson 1964 resemble Trithyrodinium evittii in that the opercula are tripartite. They differ in that the three plates of the operculum do not function as a unit. The generic name Trithyrodinium has been used informally by Dr. Evitt of Stanford University who has long been aware of such Deflandrea-like forms with tripartite opercula.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Trithyrodinium evittii Drugg, 1967. Trithyrodinium evittii has an archeopyle composed of three anterior intercalary plates. Operculum foederate. Pericyst rounded with one short apical and two short antapical horns. The periphragm is thin and smooth. Large circular endocyst filling pericyst except in area or horns. Cornucavate. Endocyst about 1 µm thick and often finely punctate. Isolated endocysts common. Cingulum more or less circular and delineated by low flanges. Length: 75-95 µm, width 60-80 µm.
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Trithyrodinium evittii Drugg, 1967, p.20, pl.3, figs.2–3; pl.9, fig.2.
Holotype: Drugg, 1967, pl.3, fig.2.
Taxonomic junior synonym: Trithyrodinium fragile, according to Nøhr-Hansen and Dam (1999, p.129).
Locus typicus: Escarpado Canyon, California
Stratum typicum: Danian
---------------------------------------------------------------------------------------------------
Original diagnosis: Drugg, 1967, p.20
Similar in morphology to members of the genus Deflandrea except that the archeopyle operculum is composed of three intercalary plates functioning as a unit (see pl. 9 fig. 2). Test rounded with one short apical and two short antapical horns. The test wall is thin and smooth. The test cavity is filled by a large rounded cyst of fairly rigid construction. The cyst wall is about 1 µm thick and often finely punctate. The cysts are commonly found separated from the tests in which case they are easily identifiable by the peculiar nature of the opening. A circular girdle is present on the test and is delineated by low flanges. A longitudinal furrow is suggested by folds originating near the antapical horns. The length of the test ranges from 75 to 95 µm and the width ranges from 60 to 80 µm.
Affinities:
Drugg, 1967, p.20: The forms Deflandrea thomasi Cookson and Eisenack 1961, D. granulifera Manum 1963, D. verrucosa Manum 1963, and Hexagonifera suspecta Manum and Cookson 1964 resemble Trithyrodinium evittii in that the opercula are tripartite. They differ in that the three plates of the operculum do not function as a unit. The generic name Trithyrodinium has been used informally by Dr. Evitt of Stanford University who has long been aware of such Deflandrea-like forms with tripartite opercula.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Trithyrodinium evittii Drugg, 1967. Trithyrodinium evittii has an archeopyle composed of three anterior intercalary plates. Operculum foederate. Pericyst rounded with one short apical and two short antapical horns. The periphragm is thin and smooth. Large circular endocyst filling pericyst except in area or horns. Cornucavate. Endocyst about 1 µm thick and often finely punctate. Isolated endocysts common. Cingulum more or less circular and delineated by low flanges. Length: 75-95 µm, width 60-80 µm.
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