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Charlesdowniea tenuivirgula
Charlesdowniea tenuivirgula, (Williams and Downie, 1966), Lentin and Vozzhennikova, 1989
Originally Wetzeliella, subsequently Kisselevia, thirdly Charlesdowniea, fourthly (and now) Sophismatia.
Holotype: Williams and Downie, 1966, pl.20, fig.2,4, text-fig.49
Locus typicus: London Clay, Sheppey, England
Stratum typicum: Early Eocene
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Original description as Wetzeliella (Wetzeliella) tenuivirgula: [Williams and Downie 1966, p. 188-189]:
Diagnosis:
Periphragm outline pentagonal to ovoidal, with each angle produced into a well developed tapering horn - one apical, two lateral and one or two antapical. Right antapical horn always the longer. Periphragm flattened in cross section, save medially where it encloses the ovoidal capsule. Hollow, slender or branched processes arising from periphragm and arranged in simulate complexes or occurring haphazardly within complexes. Processes terminating distally in elongate, solid secae, sometimes united to secae of adjacent processes; giving rise to interconnections between processes on opposite sides of plate or remaining unconnected.
Tabulation typical of genus, with three sulcal plates.
Archaeopyle usually formed.
Description:
W. tenuivirgula commonly has an outline similar to that of W. articulata, with two well-developed antapical horns, although the left is absent in some individuals. The apical and antapical horns are acuminate distally; the lateral horns are indented, denoting the position of a cingulum. The processes tend to be graded, being longest furthest away from the horns.
Dimensions:
Periphragm, length 125-175 µm; breadth 120-158 µm. Capsule, length, 72-113 µm; breadth 70-104 µm.
Affinities:
In some specimens the majority of the processes are regularly arranged just within the plate boundary and form a simulate complex; they may also arise nearer the plate centre. The secae, besides uniting adjacent processes, often extend across the plate, thus giving rise to a very loosely knit reticulum, totally different, in appearance to that found in W. reticulata. Unconnected acuminate spines, up to 2-3 µm in length, often arise from the interconnecting secae or trabeculae. The trabeculae may be granular or smooth; the secae are usually extremely fine and regular. Processes of adjacent plates are not united. The pre- or postcingular plates may or may not have processes on the side nearest the cingulum. The capsule almost fills the pericoel, apart from the horns, and has a slightly granular wall. W. tenuivirgula differs from W. reticulata in the nature of the secae; in the latter species these are short and complexly anastomosing and are rarely unconnected.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Charlesdowniea tenuivirgula (Williams and Downie, 1966b) Lentin and Vozzhennikova, 1989, has processes terminating distally in elongate, solid secae, sometimes united to secae of adjacent processes, giving rise to interconnections between processes on opposite sides of the plate or remaining unconnected. Processes of adjacent plates are not united.
Size: pericyst length 125-175 µm, width 120-158 µm, endocyst length 72-113 µm, width 70-104 µm
Originally Wetzeliella, subsequently Kisselevia, thirdly Charlesdowniea, fourthly (and now) Sophismatia.
Holotype: Williams and Downie, 1966, pl.20, fig.2,4, text-fig.49
Locus typicus: London Clay, Sheppey, England
Stratum typicum: Early Eocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Wetzeliella (Wetzeliella) tenuivirgula: [Williams and Downie 1966, p. 188-189]:
Diagnosis:
Periphragm outline pentagonal to ovoidal, with each angle produced into a well developed tapering horn - one apical, two lateral and one or two antapical. Right antapical horn always the longer. Periphragm flattened in cross section, save medially where it encloses the ovoidal capsule. Hollow, slender or branched processes arising from periphragm and arranged in simulate complexes or occurring haphazardly within complexes. Processes terminating distally in elongate, solid secae, sometimes united to secae of adjacent processes; giving rise to interconnections between processes on opposite sides of plate or remaining unconnected.
Tabulation typical of genus, with three sulcal plates.
Archaeopyle usually formed.
Description:
W. tenuivirgula commonly has an outline similar to that of W. articulata, with two well-developed antapical horns, although the left is absent in some individuals. The apical and antapical horns are acuminate distally; the lateral horns are indented, denoting the position of a cingulum. The processes tend to be graded, being longest furthest away from the horns.
Dimensions:
Periphragm, length 125-175 µm; breadth 120-158 µm. Capsule, length, 72-113 µm; breadth 70-104 µm.
Affinities:
In some specimens the majority of the processes are regularly arranged just within the plate boundary and form a simulate complex; they may also arise nearer the plate centre. The secae, besides uniting adjacent processes, often extend across the plate, thus giving rise to a very loosely knit reticulum, totally different, in appearance to that found in W. reticulata. Unconnected acuminate spines, up to 2-3 µm in length, often arise from the interconnecting secae or trabeculae. The trabeculae may be granular or smooth; the secae are usually extremely fine and regular. Processes of adjacent plates are not united. The pre- or postcingular plates may or may not have processes on the side nearest the cingulum. The capsule almost fills the pericoel, apart from the horns, and has a slightly granular wall. W. tenuivirgula differs from W. reticulata in the nature of the secae; in the latter species these are short and complexly anastomosing and are rarely unconnected.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Charlesdowniea tenuivirgula (Williams and Downie, 1966b) Lentin and Vozzhennikova, 1989, has processes terminating distally in elongate, solid secae, sometimes united to secae of adjacent processes, giving rise to interconnections between processes on opposite sides of the plate or remaining unconnected. Processes of adjacent plates are not united.
Size: pericyst length 125-175 µm, width 120-158 µm, endocyst length 72-113 µm, width 70-104 µm