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Dracodinium varielongitudum
Dracodinium varielongitudum (Williams and Downie, 1966) Costa and Downie, 1979
Originally Wetzeliella, subsequently (and now) Dracodinium.
Holotype: Williams and Downie, 1966, pl.20, fig.4
Locus typicus: London Clay, Sheppey, England
Stratum typicum: early Eocene
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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.
Dracodinium varielongitudum (Williams and Downie, 1966b) Costa and Downie, 1979, has short, broad lateral horns, a short, wide apical horn, and one well-developed antapical horn. Endocyst thick-walled, often coarsely granular. Processes extremely short on the ambitus and increasing in length further away. Processes bifid, acuminate or evexate. Size: pericyst length 96-126 µm, width 90-125 µm, endocyst length 64-79 µm, width 63-84 µm.
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Original diagnosis: Williams and Downie, 1966, p. 196-197: Wetzeliella (Wetzeliella) varielongituda
Periphragm outline sub-rhomboidal, with short broad lateral horns, a short wide apical horn and one well developed (right) antapical horn. Left antapical horn represented by slight protuberance on left antapical margin. Capsule thick walled, often coarsely granular. Processes extremely short on ambitus of periphragm and increasing in length further away from ambitus. Distally processes bifid, aculeate, acuminate or evexate.
Dimensions: holotype: outer shell, length 103 Ám, breadth 100 Ám. Capsule, length 73 Ám, breadth 71 Ám, Observed range: outer shell, length 96-126 Ám, breadth 90-125 Ám. Capsule, length 64-79 Ám, breadth 63-84 Ám. Length / breadth ratio of pericoel 1-1 to 1.1-1.
Original description: Williams and Davey, 1966, p. 197: Wetzeliella (Wetzeliella) varielongituda
One of the diagnostic features of W. varielongituda are the processes. The wall of the periphragm is up to 1/2 Ám in thickness, so that the slender processes have only a minute central tubule, along their length. They are distally closed, proximally open to the pericoel. The processes can be granular and are always simple. The shortest processes occur on the ambitus of the pericoel and particularly is this so on the lateral horns and epitract. It is these processes that can be acuminate or evexate distally. The processes are regularly orientated in simulate complexes or are irregular occurring within the complexes. Typical Wetzeliella tabulation is decipherable, with the archeopyle intercalary.
The horns of W. varielongituda tend to be broad and low, merging imperceptibly with the lateral margins of the periphragm. This is especially so with the apical horn. The capsule is sub-circular in outline, ellipsoidal in cross section and has a wall up to 3.5 Ám thick. The wall often shows local thickening directly opposite the horns. Distance of the capsule from the inner surface of the periphragm is variable.
Affinities:
Williams and Downie, 1966, p. 197: Wetzeliella (Wetzeliella) varielongituda
The nature of the processes, outline of the pericoel and structure of the capsule readily distinguish Wetzeliella (W.) varielongituda from other species of Wetzeliella.
Heilmann-Clausen in Heilmann-Clausen and Costa, 1989, p. 465, pl.4, fig.5,6: Dracodinium cf. varielongitudum
These forms occur immediately below the first samples with typical D. varielongitudum. They seem to be transitional between D. simile and D. varielongitudum. Thus the lateral horns are rather long, like in D. simile, but their bases are broader and more confluent with the lateral margins of the cyst body, in this respect approaching D. varielongitudum.
Originally Wetzeliella, subsequently (and now) Dracodinium.
Holotype: Williams and Downie, 1966, pl.20, fig.4
Locus typicus: London Clay, Sheppey, England
Stratum typicum: early Eocene
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Dracodinium varielongitudum (Williams and Downie, 1966b) Costa and Downie, 1979, has short, broad lateral horns, a short, wide apical horn, and one well-developed antapical horn. Endocyst thick-walled, often coarsely granular. Processes extremely short on the ambitus and increasing in length further away. Processes bifid, acuminate or evexate. Size: pericyst length 96-126 µm, width 90-125 µm, endocyst length 64-79 µm, width 63-84 µm.
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Original diagnosis: Williams and Downie, 1966, p. 196-197: Wetzeliella (Wetzeliella) varielongituda
Periphragm outline sub-rhomboidal, with short broad lateral horns, a short wide apical horn and one well developed (right) antapical horn. Left antapical horn represented by slight protuberance on left antapical margin. Capsule thick walled, often coarsely granular. Processes extremely short on ambitus of periphragm and increasing in length further away from ambitus. Distally processes bifid, aculeate, acuminate or evexate.
Dimensions: holotype: outer shell, length 103 Ám, breadth 100 Ám. Capsule, length 73 Ám, breadth 71 Ám, Observed range: outer shell, length 96-126 Ám, breadth 90-125 Ám. Capsule, length 64-79 Ám, breadth 63-84 Ám. Length / breadth ratio of pericoel 1-1 to 1.1-1.
Original description: Williams and Davey, 1966, p. 197: Wetzeliella (Wetzeliella) varielongituda
One of the diagnostic features of W. varielongituda are the processes. The wall of the periphragm is up to 1/2 Ám in thickness, so that the slender processes have only a minute central tubule, along their length. They are distally closed, proximally open to the pericoel. The processes can be granular and are always simple. The shortest processes occur on the ambitus of the pericoel and particularly is this so on the lateral horns and epitract. It is these processes that can be acuminate or evexate distally. The processes are regularly orientated in simulate complexes or are irregular occurring within the complexes. Typical Wetzeliella tabulation is decipherable, with the archeopyle intercalary.
The horns of W. varielongituda tend to be broad and low, merging imperceptibly with the lateral margins of the periphragm. This is especially so with the apical horn. The capsule is sub-circular in outline, ellipsoidal in cross section and has a wall up to 3.5 Ám thick. The wall often shows local thickening directly opposite the horns. Distance of the capsule from the inner surface of the periphragm is variable.
Affinities:
Williams and Downie, 1966, p. 197: Wetzeliella (Wetzeliella) varielongituda
The nature of the processes, outline of the pericoel and structure of the capsule readily distinguish Wetzeliella (W.) varielongituda from other species of Wetzeliella.
Heilmann-Clausen in Heilmann-Clausen and Costa, 1989, p. 465, pl.4, fig.5,6: Dracodinium cf. varielongitudum
These forms occur immediately below the first samples with typical D. varielongitudum. They seem to be transitional between D. simile and D. varielongitudum. Thus the lateral horns are rather long, like in D. simile, but their bases are broader and more confluent with the lateral margins of the cyst body, in this respect approaching D. varielongitudum.