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Hystrichokolpoma rigaudiae
Hystrichokolpomarigaudiae Deflandre and Cookson, 1955, p.279-281, pl.6, figs.6,10; text-fig.42. Holotype: Deflandre and Cookson, 1955, pl.6, fig.6. Taxonomic junior synonyms: Galea xiphea and Hystrichosphaeridium stellatum, both according to Sarjeant (1983, p.104) - however, Srivastava (1995, p.306) retained Hystrichosphaeridium (as and now Florentinia) stellatum; Hystrichosphaeridium perifurcatum, according to Jain (1982, p.53). This name was not validly published in Deflandre and Cookson (1954, p.1236), who did not give a description. Age: Eocene-Miocene. Locus typicus: Australia
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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.
Hystrichokolpoma rigaudiae Deflandre and Cookson, 1955, has two types of processes. Bases of large processes form quadrangular outlines on central body. Large processes closed distally, generally widened and provided with more or less numerous and sometimes relatively long horns. The narrow tubular processes are slightly widened or divided at their extremities which are either open or closed; when open they have denticulate to aculeate margins. There are about 10 equatorial processes. Size: central body 35-45 µm, length of processes 20-30 µm, width of large processes 8-13 µm, length of narrow processes 18-25 µm.
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Original description: Deflandre and Cookson, 1955, p. 279-281.
Shell globular, more or less ellipsoidal, with approximately axial symmetry and processes of two kinds not communicating with the interior, disposed in parallel series starting from one pole considered as apical. Antapical pole with a large aperture having a straight or angular margin. Bases of the large processes marked by lines forming quadrangular area that give the impression of plates. Large processes always closed at their distal extremities, generally widened and provided with more or less numerous and sometimes relatively long horns. The large process situated at the apical pole is often longer than the others and is sometimes prolonged into a hollow horn. The narrow tubular processes are slightly widened or divided at their extremities, which are wither open or closed. Certain filiform processes seem to be solid throughout. The narrow processes forming the equatorial series are about 10 in number, of which some may be paired. Between the equatorial series and the apex there is a circle of 4 large appendages and a space occupied by a small number (3-5) of narrow processes similar to those of the equatorial belt. Below the equator there is a circle of 6 large processes, or in certain specimens one of these processes may, perhaps, be duplicated or replaced by several thinner appendages. Membrane of the shell smooth or indistinctly granular.
Dimensions: Diameter of shell c. 35-45 Ám, length of processes 20-30 Ám, breadth of large processes 8-13 Ám, length of narrow processes 18-25 Ám.
Remarks: H. rigaudiae differs considerably from H. cinctum Klumpp, the type species of the genus: (i) in the general form of the large processes, which are rarely cylindrical but usually slightly narrowed and then widened at their extremities, which are always closed; (ii) in the smaller number of narrow although apparently more robust equatorial processes. Klumpp (1953) has indicated that the large cornet-shaped appendages are wither widely open or prolonged into a point with a small terminal opening, the latter apparently the normal condition, the former more likely the result of imperfect preservation.
Matsuoka and Bujak, 1988, p.47
Thecal affinities: Based on the paratabulation represented by the processes and archeopyle, Hystrichokolpoma rigaudiae may have affinities with the Gonyaulacaceae. However, no modern genus of this family possesses 1" and 2~ paraplates which are strongly reduced, and a 4' paraplate which contacts the anterior sulcal paraplate, all features characteristic of Hystrichokolpoma.
Heilmann-Clausen in Heilmann-Clausen and Costa, 1989, p. 466, pl 15, fig.2,3: Hystrichokolpoma aff. rigaudiae
The antapical process is lagenate and distally closed, like in H. rigaudae. Other processes are tubiform with ramified aculei at the distal endings. These processes also appear to be closed.
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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.
Hystrichokolpoma rigaudiae Deflandre and Cookson, 1955, has two types of processes. Bases of large processes form quadrangular outlines on central body. Large processes closed distally, generally widened and provided with more or less numerous and sometimes relatively long horns. The narrow tubular processes are slightly widened or divided at their extremities which are either open or closed; when open they have denticulate to aculeate margins. There are about 10 equatorial processes. Size: central body 35-45 µm, length of processes 20-30 µm, width of large processes 8-13 µm, length of narrow processes 18-25 µm.
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Original description: Deflandre and Cookson, 1955, p. 279-281.
Shell globular, more or less ellipsoidal, with approximately axial symmetry and processes of two kinds not communicating with the interior, disposed in parallel series starting from one pole considered as apical. Antapical pole with a large aperture having a straight or angular margin. Bases of the large processes marked by lines forming quadrangular area that give the impression of plates. Large processes always closed at their distal extremities, generally widened and provided with more or less numerous and sometimes relatively long horns. The large process situated at the apical pole is often longer than the others and is sometimes prolonged into a hollow horn. The narrow tubular processes are slightly widened or divided at their extremities, which are wither open or closed. Certain filiform processes seem to be solid throughout. The narrow processes forming the equatorial series are about 10 in number, of which some may be paired. Between the equatorial series and the apex there is a circle of 4 large appendages and a space occupied by a small number (3-5) of narrow processes similar to those of the equatorial belt. Below the equator there is a circle of 6 large processes, or in certain specimens one of these processes may, perhaps, be duplicated or replaced by several thinner appendages. Membrane of the shell smooth or indistinctly granular.
Dimensions: Diameter of shell c. 35-45 Ám, length of processes 20-30 Ám, breadth of large processes 8-13 Ám, length of narrow processes 18-25 Ám.
Remarks: H. rigaudiae differs considerably from H. cinctum Klumpp, the type species of the genus: (i) in the general form of the large processes, which are rarely cylindrical but usually slightly narrowed and then widened at their extremities, which are always closed; (ii) in the smaller number of narrow although apparently more robust equatorial processes. Klumpp (1953) has indicated that the large cornet-shaped appendages are wither widely open or prolonged into a point with a small terminal opening, the latter apparently the normal condition, the former more likely the result of imperfect preservation.
Matsuoka and Bujak, 1988, p.47
Thecal affinities: Based on the paratabulation represented by the processes and archeopyle, Hystrichokolpoma rigaudiae may have affinities with the Gonyaulacaceae. However, no modern genus of this family possesses 1" and 2~ paraplates which are strongly reduced, and a 4' paraplate which contacts the anterior sulcal paraplate, all features characteristic of Hystrichokolpoma.
Heilmann-Clausen in Heilmann-Clausen and Costa, 1989, p. 466, pl 15, fig.2,3: Hystrichokolpoma aff. rigaudiae
The antapical process is lagenate and distally closed, like in H. rigaudae. Other processes are tubiform with ramified aculei at the distal endings. These processes also appear to be closed.