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Trinovantedinium ferugnomatum
Trinovantedinium ferugnomatum De Verteuil and Norris, 1992
Holotype: De Verteuil and Norris, 1992, pl.3, figs.1-3
Locus typicus: Claremont Manor Member of the Eastover Formation, southeast of Cobham Wharf, south bank of the James River
Stratum typicum: Late Miocene
Original diagnosis: De Verteuil and Norris, 1992, p. 412
Small, proximochorate, pigmented, protoperidiniacean cyst, dorsoventrally compressed with rounded-pentagonal outline. Epicyst rounded to conical, and equal to or slightly larger than hypocyst. Antapical lobes symmetrical and poorly or moderately developed. Antapical depression shallow and wide. Processes are penitabular and intratabular, acuminate, capitate or bifid spines, hollow or solid, simple or complex, individual or forming discontinuous linear folds. Archeopyle 2a intercalary, operculum free.
Original description: De Verteuil and Norris, 1992, p. 412
The epicyst varies from straight sided to convex, with an angular to broadly rounded apex. There is no apical horn but prominent complex processes with branched primary shafts are often present at the apex. The hypocyst is straight sided to convex with two poorly developed symmetrical lobes separated by a broad (0.3-0.5 cyst diameter), straight to shallow, concave (less than 25% of the width) antapical depression. The cyst wall appears autophragmal with a finely and unevenly microgranulose texture. The cingulum is clearly marked by two rows of adcingular processes arising from low, discontinuous lists. The penitabular processes are commonly taeniate, as are the complex processes which occur at the apex and antapex. Simple, individual, intratabular processes occur variably on specimens but tend to be largely restricted to areas not including the 2a intercalary plate and the sulcus. The sulcus is shallow and featureless except for the two, 2-3 µm, vertically arranged flagellar scars that occur below the line of the cingulum. The archeopyle is 2a steno- to lati-deltaform with detached operculum.
Dimensions. Length, excluding processes, 30(39)55 µm; holotype 41 µm. Breadth at cingulum, excluding processes: 30(39)48 µm; holotype, 43 µm. Process length, 3-6 µm. Thirty-two specimens measured.
Affinities:
De Verteuil and Norris, 1992, p. 412: Of the three new species of Trinovantedinium described herein, T. ferugnomatum is the smallest. T. papulum has a denser covering of capitate spines which only rarely bifurcate, and T. harpagonium is characterized by an intermediate distribution of orthogonal to recurved bifid processes. T. variabile (Bujak 1984) De Verteuil and Norris, 1992 has flared, aculeate process terminations. T. ferugnomatum is similar in size and shape to T. boreale Bujak 1984, but does not develop the left antapical asymmetry typical of the latter species. Also, in T. boreale the cyst ornament consists almost exclusively of distally capitate spines.
Holotype: De Verteuil and Norris, 1992, pl.3, figs.1-3
Locus typicus: Claremont Manor Member of the Eastover Formation, southeast of Cobham Wharf, south bank of the James River
Stratum typicum: Late Miocene
Original diagnosis: De Verteuil and Norris, 1992, p. 412
Small, proximochorate, pigmented, protoperidiniacean cyst, dorsoventrally compressed with rounded-pentagonal outline. Epicyst rounded to conical, and equal to or slightly larger than hypocyst. Antapical lobes symmetrical and poorly or moderately developed. Antapical depression shallow and wide. Processes are penitabular and intratabular, acuminate, capitate or bifid spines, hollow or solid, simple or complex, individual or forming discontinuous linear folds. Archeopyle 2a intercalary, operculum free.
Original description: De Verteuil and Norris, 1992, p. 412
The epicyst varies from straight sided to convex, with an angular to broadly rounded apex. There is no apical horn but prominent complex processes with branched primary shafts are often present at the apex. The hypocyst is straight sided to convex with two poorly developed symmetrical lobes separated by a broad (0.3-0.5 cyst diameter), straight to shallow, concave (less than 25% of the width) antapical depression. The cyst wall appears autophragmal with a finely and unevenly microgranulose texture. The cingulum is clearly marked by two rows of adcingular processes arising from low, discontinuous lists. The penitabular processes are commonly taeniate, as are the complex processes which occur at the apex and antapex. Simple, individual, intratabular processes occur variably on specimens but tend to be largely restricted to areas not including the 2a intercalary plate and the sulcus. The sulcus is shallow and featureless except for the two, 2-3 µm, vertically arranged flagellar scars that occur below the line of the cingulum. The archeopyle is 2a steno- to lati-deltaform with detached operculum.
Dimensions. Length, excluding processes, 30(39)55 µm; holotype 41 µm. Breadth at cingulum, excluding processes: 30(39)48 µm; holotype, 43 µm. Process length, 3-6 µm. Thirty-two specimens measured.
Affinities:
De Verteuil and Norris, 1992, p. 412: Of the three new species of Trinovantedinium described herein, T. ferugnomatum is the smallest. T. papulum has a denser covering of capitate spines which only rarely bifurcate, and T. harpagonium is characterized by an intermediate distribution of orthogonal to recurved bifid processes. T. variabile (Bujak 1984) De Verteuil and Norris, 1992 has flared, aculeate process terminations. T. ferugnomatum is similar in size and shape to T. boreale Bujak 1984, but does not develop the left antapical asymmetry typical of the latter species. Also, in T. boreale the cyst ornament consists almost exclusively of distally capitate spines.