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Heteraulacacysta campanula
Heteraulacacysta campanula Drugg and Loeblich, 1967
Holotype: Drugg and Loeblich, 1967, pl.1, fig.8a-c
Paratype: Drugg and Loeblich, 1967, pl 1, fig.6-7
Locus typicus: Little Stave Creek, 3,5 miles N of Jackson, Washington County, Alabama, U.S.A.
Stratum typicum: Middle 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.
Heteraulacacysta campanula Drugg and Loeblich, Jr., 1967, has thin endophragm and periphragm. The endophragm is smooth, the periphragm is commonly ornamented with grana and irregular spines that may fuse to form a crude microreticulum. The sutural ledges are 5 µm high and radially striate. The cingular flanges are 7 µm wide and are also radially striate. Size: length 55-72 µm, width 63-97 µm.
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Original description: Drugg and Loeblich, 1967, p. 183-184
Diagnosis (same as for the genus with additional comments): Proximate fossil cyst with a cingular archeopyle. The epitract is bell-shaped, the hypotract is cup-shaped, and the transverse section is more or less circular. The tabulation is 3', 7'', 5''', 3''''. Plates 1'' and 7'' are commonly absent or weakly expressed. Both endophragm and periphragm are thin. The endophragm is smooth but the periphragm is commonly ornamented with grana and irregular spines that may fuse to form a very crude microreticulum. The sutural ledges arise from the periphragm and are about 5 Ám wide and are radially striate. The cingular flanges are about 7 Ám wide and radially striate. They fit closely together with no cingular furrow between them, but they may be displaced laterally from each other. The tabulation is clearly of the Heteraulacus type (text-fig. 2a-d) except that plates 1'' and 7'' are indistinct or absent alltogether, being submerged in the sulcal furrow. Morgenroth (1966, p. 7, pl. 2, fig. 7-9) described a fossil form which he referred to the extant species Goniodoma polyedricum (Pouchet) J÷rgensen, 1899. This fossil form exhibits plates 1'' and 7'' very clearly. A small triangular area, present at the apex of the epitract, presumably reflects the apical pore of the living Heteraulacus.
Dimensions: Holotype, 70 Ám high, 90 Ám wide. Range 55-72 Ám high, 63-97 Ám wide. The holotype is of average size.
Matsuoka and Bujak, 1988, p.46
Thecal affinities: This species may be closely related to the modern genus Triadinium ( = Goniodoma Stein, 1883, or Heteraulacus Diesing, 1850). Drugg and Loeblich (1967) observed that the paratabulation of Heteraulacacysta campanula is similar to that of modern thecate species Triadinium polyedricus ( = Heteraulacus polyedricus), particularly with respect to the presence of an apical pore paraplate and three antapical paraplates. Stover and Evitt (1978) subsequently considered that this cyst species is more closely related to the genus Pyrodinium than to the Triadinium, but did not clarify their opinion.
Pyrodinium and Triadinium hoth have the same plate formula of 3', 7", 6c, 6''', 1'''', 1p, 5s, but the distinction between them is based on the distribution of plates. In the genus Triadinium the first precingular plate is separated from the second apical plate, whereas in the genus Pyrodinium plate 1" contacts plate 2'.
According to the present observations and the paratypes illustrated by Drugg and Loeblich (1967; pl. 1, fig. 6), Heteraulacacysta campanula does not possess a first precingular paraplate which contacts the second apical paraplate. H. campanula may therefore be more closely related to the modern genus Triadinium.
Holotype: Drugg and Loeblich, 1967, pl.1, fig.8a-c
Paratype: Drugg and Loeblich, 1967, pl 1, fig.6-7
Locus typicus: Little Stave Creek, 3,5 miles N of Jackson, Washington County, Alabama, U.S.A.
Stratum typicum: Middle 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.
Heteraulacacysta campanula Drugg and Loeblich, Jr., 1967, has thin endophragm and periphragm. The endophragm is smooth, the periphragm is commonly ornamented with grana and irregular spines that may fuse to form a crude microreticulum. The sutural ledges are 5 µm high and radially striate. The cingular flanges are 7 µm wide and are also radially striate. Size: length 55-72 µm, width 63-97 µm.
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Original description: Drugg and Loeblich, 1967, p. 183-184
Diagnosis (same as for the genus with additional comments): Proximate fossil cyst with a cingular archeopyle. The epitract is bell-shaped, the hypotract is cup-shaped, and the transverse section is more or less circular. The tabulation is 3', 7'', 5''', 3''''. Plates 1'' and 7'' are commonly absent or weakly expressed. Both endophragm and periphragm are thin. The endophragm is smooth but the periphragm is commonly ornamented with grana and irregular spines that may fuse to form a very crude microreticulum. The sutural ledges arise from the periphragm and are about 5 Ám wide and are radially striate. The cingular flanges are about 7 Ám wide and radially striate. They fit closely together with no cingular furrow between them, but they may be displaced laterally from each other. The tabulation is clearly of the Heteraulacus type (text-fig. 2a-d) except that plates 1'' and 7'' are indistinct or absent alltogether, being submerged in the sulcal furrow. Morgenroth (1966, p. 7, pl. 2, fig. 7-9) described a fossil form which he referred to the extant species Goniodoma polyedricum (Pouchet) J÷rgensen, 1899. This fossil form exhibits plates 1'' and 7'' very clearly. A small triangular area, present at the apex of the epitract, presumably reflects the apical pore of the living Heteraulacus.
Dimensions: Holotype, 70 Ám high, 90 Ám wide. Range 55-72 Ám high, 63-97 Ám wide. The holotype is of average size.
Matsuoka and Bujak, 1988, p.46
Thecal affinities: This species may be closely related to the modern genus Triadinium ( = Goniodoma Stein, 1883, or Heteraulacus Diesing, 1850). Drugg and Loeblich (1967) observed that the paratabulation of Heteraulacacysta campanula is similar to that of modern thecate species Triadinium polyedricus ( = Heteraulacus polyedricus), particularly with respect to the presence of an apical pore paraplate and three antapical paraplates. Stover and Evitt (1978) subsequently considered that this cyst species is more closely related to the genus Pyrodinium than to the Triadinium, but did not clarify their opinion.
Pyrodinium and Triadinium hoth have the same plate formula of 3', 7", 6c, 6''', 1'''', 1p, 5s, but the distinction between them is based on the distribution of plates. In the genus Triadinium the first precingular plate is separated from the second apical plate, whereas in the genus Pyrodinium plate 1" contacts plate 2'.
According to the present observations and the paratypes illustrated by Drugg and Loeblich (1967; pl. 1, fig. 6), Heteraulacacysta campanula does not possess a first precingular paraplate which contacts the second apical paraplate. H. campanula may therefore be more closely related to the modern genus Triadinium.