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Enneadocysta partridgei
Enneadocysta partridgei Stover and Williams, 1995
Taxonomic senior synonym: Hystrichosphaeridium (as Enneadocysta) dictyostilum, according to Fensome et al. (2007, p.396).
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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.
Enneadocysta partidgei Stover and Williams, 1995, has 21 to 23 processes, nine or 10 on the epicyst, nine on the hypocyst and three to five paracingular processes. Processes slightly to moderately expanded distally, simply branched, or more commonly, vasiform; expanded part irregularly fenestrate or reticulate, ends may be recurved and margins more or less circular, very rarely polygonal and uneven to ragged. 3"’ tends to be the widest of the postcingular processes. Process formula is 4', 5-6", 3-5c, 6"’, 2"”, 1ps. Usually four paracingular processes. Size: body length 44 - 58 µm, overall 88-128 µm. This species, from the Southern Hemisphere, was previously identified as Areosphaeridium diktyplokum
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Stover and Williams, 1995, p. 113-114
Plate 4, figures 4a-e, 5; plate 5, figures 1a-c, 2a-c, 3a-c, 4, 5a-b: text-figure 1, nos. D, J
- Hystrichosphaeridium sp. Canwell et al. 1960, p. 701, fig. 1
- Cordosphaeridium diktyoplokus (Klumpp 1953) Eisenack 1963b, Cranwell 1964, p. 398-404, figs. 2,3a-3c
- Areosphaeridium diktyoplokus (Klumpp 1953) Eaton 1971, Haskell and Wilson 1975, p.724, pl.1, fig.1
- Areosphaeridium sp. cf. Areosphaeridium diktyoplokus (Klumpp 1953) Eaton 1971, Goodman and Ford 1983, p. 865, pl. 8, fig.4
- Areosphaeridium diktyoplokus (Klumpp 1953) Eaton 1971. Wrenn and Hart 1988. p. 346-347. fig. 15. no. 6.
Description:
Shape: Cysts skolochorate, occasionally subspherical, but more frequently lenticular with parasulcal notch offset to the left.
Wall relafionships: Autophragm only.
Wall features: Autophragm smooth to faintly granulate and bears 21 to 23 intratabular processes, nine or 10 on epicyst, nine on hypocyst and three to five paracingular processes. Process stems solid and faintly fibroid, narrowest at about mid-length and rarely fenestrate or branched. Processes slightly to moderately expanded distally, simply branched, or more commonly, vasiform; expanded part irregularly fenestrate or reticulate, ends may be recurved, and margins are more or less circular, very rarely polygonal, and uneven to ragged. Process length fairly uniform on individual specimens; however, the width of stems at mid-length differs somewhat depending on positions of processes, with the wider processes occurring on the precingular and postcingular paraplates on the dorsal surface. Stems of paracingular processes are narrow, about 1.0 to 2.0 Ám wide and their tips are correspondingly smaller and less complex than those on processes with wider stems. The distal ends are usually vasiform with ragged margins, but may also be "T"- or "V"-shaped and transversely elongate. Of the nine hypocystal processes, 3''' is generally wider than the others (pl. 5, fig. 1 c),which tend to be more or less similar in size.
Excystment type: Archeopyle apical; operculum tetratabular, simple, generally longer transversely than dorso-ventrally, because of dorso-ventral compression, and free. Operculum always bears four processes, with one of the dorsal processes sometimes branched.
Paratabulation: Indicated on the epicyst by principal archeopyle suture, short accessory sutures and locations of intratabular processes. Elsewhere on central body, paratabulation indicated solely by process positions. Process formula: 4', 5-6'', 3-5c, 6''', 2'''', 1ps. First and last precingular paraplates approximately equal in width; peaked anterior margin of paraplate 6'' asymmetrical, with left side shorter than right. Hypocystal processes arranged in the partiform pattern.
Paracingulum: Indicated by three to five paracingular processes. The most common number of processes is four (pl. 4, figs. 4a-e), less commonly three, rarely five. When four paracingular processes are present, they are almost always situated along the lateral surfaces, with two on the right side and two on the left side (pl. 4, figs. 4a-e). Furthermore, the positions of the paracingular processes relative to certain precingular processes appear to be constant. For example, 1c. 3c and 4c are located to the right of 1'', 3'' and 4''. respectively and 2c is either in line with or to the left of 2''.
Parasulcus: Limits of parasulcus indicated anteriorly by the position of the parasulcal notch and posteriorly by the location of the posterior sulcal process.
Size: Intermediate to large; measurement of 25 specimens: body length without opercula, 44Ám (50 Ám) 58 Ám; specimens with opercula 15 Ám to 20 Ám longer; body width including processes, 88 Ám (100 Ám) 128 Ám; length of processes, 18 Ám to 32 Ám, with the majority of processes in 24 Ám to 30 Ám range. Width of process stems, exclusive of those of paracingular processes, varies from 2.5 Ám to about 5.0 Ám at midlength. Width of distal terminations from 14 Ám to 32 Ám. Mean values are shown in parentheses.
Comments:
Of the approximately 50 specimens for which the paratabulation was determined, only one had five rather than six precingular processes (the process on paraplate 6'' was absent).
In most previous publications on Early Tertiary Southern Hemisphere dinoflagellates, this species was identified as Areosphaeridium diktyoplokus. Although Cranwell ( 1964), in consultation with A. Eisenack, noted differences between Southern and Northern Hemisphere specimens, they regarded the differences as intraspecific. Goodman and Ford (1983) were reluctant to assign Southern Hemisphere specimens unequivocally to Areosphaeridium diktyoplokus and, in fact, stated ... "We believe that none of the Southern Hemisphere forms reported to date should be attributed to A. diktyoplokus s.s.". Wrenn and Hart (1988) were less emphatic than Goodman and Ford, and assumed that specimens from both hemispheres represented one species. They remarked, however, that a comparison study was in order.
Holotype:
Specimen illustrated in Plate 4, figures 4a-e. Location: EPR slide CC11-3-2, coordinates R01.0+14.3, Exxon Production Co., Research Center, Houston, Texas. U.S.A.
Type locality and stratum:
Locality: D.S.D.P., Leg 29, Tasman Sea Site 283.
Stratum: upper Middle Eocene in core sample 11 -3 (119- 121 cm).
Stratigraphic and geographic data:
The chronostratigraphic range of Enneadocysta partridgei is late Mid Eocene (Bartonian) to Early Oligocene (Rupelian).
Enneadocysta partridgei is confined to the Southern Hemisphere. It has been recorded from Antarctica, Antarctic Ocean (Seymour Island), Tasman Sea, Australia, New Zealand, Argentina, Brazil, Chile and South Atlantic Ocean (Falkland Plateau). Pre-upper Mid Eocene occurrences require verification.
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Taxonomic senior synonym: Hystrichosphaeridium (as Enneadocysta) dictyostilum, according to Fensome et al. (2007, p.396).
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Enneadocysta partidgei Stover and Williams, 1995, has 21 to 23 processes, nine or 10 on the epicyst, nine on the hypocyst and three to five paracingular processes. Processes slightly to moderately expanded distally, simply branched, or more commonly, vasiform; expanded part irregularly fenestrate or reticulate, ends may be recurved and margins more or less circular, very rarely polygonal and uneven to ragged. 3"’ tends to be the widest of the postcingular processes. Process formula is 4', 5-6", 3-5c, 6"’, 2"”, 1ps. Usually four paracingular processes. Size: body length 44 - 58 µm, overall 88-128 µm. This species, from the Southern Hemisphere, was previously identified as Areosphaeridium diktyplokum
--------------------------------------------------
Stover and Williams, 1995, p. 113-114
Plate 4, figures 4a-e, 5; plate 5, figures 1a-c, 2a-c, 3a-c, 4, 5a-b: text-figure 1, nos. D, J
- Hystrichosphaeridium sp. Canwell et al. 1960, p. 701, fig. 1
- Cordosphaeridium diktyoplokus (Klumpp 1953) Eisenack 1963b, Cranwell 1964, p. 398-404, figs. 2,3a-3c
- Areosphaeridium diktyoplokus (Klumpp 1953) Eaton 1971, Haskell and Wilson 1975, p.724, pl.1, fig.1
- Areosphaeridium sp. cf. Areosphaeridium diktyoplokus (Klumpp 1953) Eaton 1971, Goodman and Ford 1983, p. 865, pl. 8, fig.4
- Areosphaeridium diktyoplokus (Klumpp 1953) Eaton 1971. Wrenn and Hart 1988. p. 346-347. fig. 15. no. 6.
Description:
Shape: Cysts skolochorate, occasionally subspherical, but more frequently lenticular with parasulcal notch offset to the left.
Wall relafionships: Autophragm only.
Wall features: Autophragm smooth to faintly granulate and bears 21 to 23 intratabular processes, nine or 10 on epicyst, nine on hypocyst and three to five paracingular processes. Process stems solid and faintly fibroid, narrowest at about mid-length and rarely fenestrate or branched. Processes slightly to moderately expanded distally, simply branched, or more commonly, vasiform; expanded part irregularly fenestrate or reticulate, ends may be recurved, and margins are more or less circular, very rarely polygonal, and uneven to ragged. Process length fairly uniform on individual specimens; however, the width of stems at mid-length differs somewhat depending on positions of processes, with the wider processes occurring on the precingular and postcingular paraplates on the dorsal surface. Stems of paracingular processes are narrow, about 1.0 to 2.0 Ám wide and their tips are correspondingly smaller and less complex than those on processes with wider stems. The distal ends are usually vasiform with ragged margins, but may also be "T"- or "V"-shaped and transversely elongate. Of the nine hypocystal processes, 3''' is generally wider than the others (pl. 5, fig. 1 c),which tend to be more or less similar in size.
Excystment type: Archeopyle apical; operculum tetratabular, simple, generally longer transversely than dorso-ventrally, because of dorso-ventral compression, and free. Operculum always bears four processes, with one of the dorsal processes sometimes branched.
Paratabulation: Indicated on the epicyst by principal archeopyle suture, short accessory sutures and locations of intratabular processes. Elsewhere on central body, paratabulation indicated solely by process positions. Process formula: 4', 5-6'', 3-5c, 6''', 2'''', 1ps. First and last precingular paraplates approximately equal in width; peaked anterior margin of paraplate 6'' asymmetrical, with left side shorter than right. Hypocystal processes arranged in the partiform pattern.
Paracingulum: Indicated by three to five paracingular processes. The most common number of processes is four (pl. 4, figs. 4a-e), less commonly three, rarely five. When four paracingular processes are present, they are almost always situated along the lateral surfaces, with two on the right side and two on the left side (pl. 4, figs. 4a-e). Furthermore, the positions of the paracingular processes relative to certain precingular processes appear to be constant. For example, 1c. 3c and 4c are located to the right of 1'', 3'' and 4''. respectively and 2c is either in line with or to the left of 2''.
Parasulcus: Limits of parasulcus indicated anteriorly by the position of the parasulcal notch and posteriorly by the location of the posterior sulcal process.
Size: Intermediate to large; measurement of 25 specimens: body length without opercula, 44Ám (50 Ám) 58 Ám; specimens with opercula 15 Ám to 20 Ám longer; body width including processes, 88 Ám (100 Ám) 128 Ám; length of processes, 18 Ám to 32 Ám, with the majority of processes in 24 Ám to 30 Ám range. Width of process stems, exclusive of those of paracingular processes, varies from 2.5 Ám to about 5.0 Ám at midlength. Width of distal terminations from 14 Ám to 32 Ám. Mean values are shown in parentheses.
Comments:
Of the approximately 50 specimens for which the paratabulation was determined, only one had five rather than six precingular processes (the process on paraplate 6'' was absent).
In most previous publications on Early Tertiary Southern Hemisphere dinoflagellates, this species was identified as Areosphaeridium diktyoplokus. Although Cranwell ( 1964), in consultation with A. Eisenack, noted differences between Southern and Northern Hemisphere specimens, they regarded the differences as intraspecific. Goodman and Ford (1983) were reluctant to assign Southern Hemisphere specimens unequivocally to Areosphaeridium diktyoplokus and, in fact, stated ... "We believe that none of the Southern Hemisphere forms reported to date should be attributed to A. diktyoplokus s.s.". Wrenn and Hart (1988) were less emphatic than Goodman and Ford, and assumed that specimens from both hemispheres represented one species. They remarked, however, that a comparison study was in order.
Holotype:
Specimen illustrated in Plate 4, figures 4a-e. Location: EPR slide CC11-3-2, coordinates R01.0+14.3, Exxon Production Co., Research Center, Houston, Texas. U.S.A.
Type locality and stratum:
Locality: D.S.D.P., Leg 29, Tasman Sea Site 283.
Stratum: upper Middle Eocene in core sample 11 -3 (119- 121 cm).
Stratigraphic and geographic data:
The chronostratigraphic range of Enneadocysta partridgei is late Mid Eocene (Bartonian) to Early Oligocene (Rupelian).
Enneadocysta partridgei is confined to the Southern Hemisphere. It has been recorded from Antarctica, Antarctic Ocean (Seymour Island), Tasman Sea, Australia, New Zealand, Argentina, Brazil, Chile and South Atlantic Ocean (Falkland Plateau). Pre-upper Mid Eocene occurrences require verification.
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