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Valvaeodinium atlanticum
Valvaedinium atlanticum (Habib, 1972) Lentin and Williams, 1993
Originally Tenua Eisenack, 1958, subsequently Sentusidinium?, thirdly Fromea, fourthly Kylindrocysta, fifthly (and now) Valvaeodinium.
Taxonomic junior synonym: Fromea complicata (Appendix A), according to Davies (1983, p.31) — however, Jansonius (1989, p.65) retained Fromea complicata..
Holotype: Habib, 1972, pl.4, fig.2
Locus typicus: DSDP Leg.11 Site , North Atlantic
Stratum typicum: Callovian-Oxfordian
Original description: Habib, 1972, p. 375: Tenua atlantica
Relatively small untabulated proximate cysts. Outline of hypotract rectangular, epitract triangular. Hypotract same size or slightly larger than epitract. Cyst longer than wide; it is widest in the region of the cingulum, although a distinctive cingulum is not evident. Apical archeopyle small; its margin is zig-zag suggesting six precingular plates and a sulcus below; operculum triangular but well-rounded. Wall is thin and densely granulate.
Maximum size of seven measured specimens 24-35 µm.
Affinities:
Habib, 1972, p. 375: Tenua atlantica
This species of Tenua is distinguished by its form and small apical archeopyle. In several specimens, including the holotype, there is evidence of faint sutures reflecting a minimum of six precingular plates and five or six postcingular plates. Further detailed examination of additional specimens is necessary before it can be determined if a tabulation is present.
Originally Tenua Eisenack, 1958, subsequently Sentusidinium?, thirdly Fromea, fourthly Kylindrocysta, fifthly (and now) Valvaeodinium.
Taxonomic junior synonym: Fromea complicata (Appendix A), according to Davies (1983, p.31) — however, Jansonius (1989, p.65) retained Fromea complicata..
Holotype: Habib, 1972, pl.4, fig.2
Locus typicus: DSDP Leg.11 Site , North Atlantic
Stratum typicum: Callovian-Oxfordian
Original description: Habib, 1972, p. 375: Tenua atlantica
Relatively small untabulated proximate cysts. Outline of hypotract rectangular, epitract triangular. Hypotract same size or slightly larger than epitract. Cyst longer than wide; it is widest in the region of the cingulum, although a distinctive cingulum is not evident. Apical archeopyle small; its margin is zig-zag suggesting six precingular plates and a sulcus below; operculum triangular but well-rounded. Wall is thin and densely granulate.
Maximum size of seven measured specimens 24-35 µm.
Affinities:
Habib, 1972, p. 375: Tenua atlantica
This species of Tenua is distinguished by its form and small apical archeopyle. In several specimens, including the holotype, there is evidence of faint sutures reflecting a minimum of six precingular plates and five or six postcingular plates. Further detailed examination of additional specimens is necessary before it can be determined if a tabulation is present.