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Hystrichokolpoma reductum
Hystrichokolpoma "reductum" Zevenboom and Santarelli in Zevenboom, 1995, p.138, pl.4, figs.7-12. Holotype: Zevenboom, 1995, pl.4, figs.7-9. Name not validly published: considered a manuscript name. Age: latest Early Miocene.
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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 reductum Zevenboom and Santarelli in Zevenboom, 1995. Diagnosis from Zevenboom and Santarelli in Zevenboom (1995, p.138), is a species of Hystrichokolpoma with large penitabular processes, except those reflecting paraplates 6" and 1"’. The parasulcal and paracingular processes are not reflected. Fourteen processes are consistently present, twelve large and two small. Paraplates 2"’ and 3"’ lack processes. The large processes are hollow, slightly fibrous and distally closed, denticulate and perforate. Size: length 40-50 µm, width 50-72 µm, process length 30-40 µm.
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Original description (Zevenboom, 1995)
Manuscript holotype: Sample Sc 99/1, EF(U27), Plate IV, 7-9.
Manuscript paratype: Sample Sc 99/3, EF (G67/3), Plate IV, 10-12
Etmology: In reference to the lack of the paracingular and parasulcal processes and the reducation in number of penitabular processes.
Type locality: Santa Croce di Arcevia section, near Santa Croce, Northeastern Appenines, Italy.
Type stratum: Schlier Formation.
Diagnosis: A species of Hystrichokolpoma with large penitabular processes except those reflecting paraplates 6" and 1"'. The parasulcal and paracingular processes are not reflected.
Dimensions: Height: 40 (45) 50 µm; Width: 50 (58)72 µm, Processes: 30(37)40 µm. N=12.
Description: A species of Hystrichokolpoma with a smooth to faintly granulate periphragm. The endophragm is smooth apart from apical processes, fourteen processes are consistently present, twelve large and two smaller ones. The two smaller processes reflect paraplates 6"and 1"', whereas paraplates 2"', 3"' lack processes. The large processes are hollow, slightly fibrous and distally closed, denticulate and perforate. The archaeopyle is apical (tA). The operculum is free.
Discussion: Hystrichokolpoma reducta differs from all other Hystrichokolpoma species except Hystrichokolpoma pseudooceanicum Zevenboom and Santarelli, 1995 in the reduction or absence of paracingular and parasulcal processes. It differs from Hystrichokolpoma pseudooceanicum Zevenboom and Santarelli, 1995, by its much larger size and thicker wall and by possesing two types of processes instead of only one type. Hystrichokolpoma reducta is also similar to Dinocyst sp. D (Head et al., 1989b) but differs by having an apical archaeopyle rather than an epicystal one and by the consistent presence of the two smaller processes.
Occurences. Italy (this study, Powell, 1986b and Zevenboom et al., 1994 and Zevenboom in press, b, c).
Stratigraphic range: Latest Early Miocene (this study), see Fig. 5.
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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 reductum Zevenboom and Santarelli in Zevenboom, 1995. Diagnosis from Zevenboom and Santarelli in Zevenboom (1995, p.138), is a species of Hystrichokolpoma with large penitabular processes, except those reflecting paraplates 6" and 1"’. The parasulcal and paracingular processes are not reflected. Fourteen processes are consistently present, twelve large and two small. Paraplates 2"’ and 3"’ lack processes. The large processes are hollow, slightly fibrous and distally closed, denticulate and perforate. Size: length 40-50 µm, width 50-72 µm, process length 30-40 µm.
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Original description (Zevenboom, 1995)
Manuscript holotype: Sample Sc 99/1, EF(U27), Plate IV, 7-9.
Manuscript paratype: Sample Sc 99/3, EF (G67/3), Plate IV, 10-12
Etmology: In reference to the lack of the paracingular and parasulcal processes and the reducation in number of penitabular processes.
Type locality: Santa Croce di Arcevia section, near Santa Croce, Northeastern Appenines, Italy.
Type stratum: Schlier Formation.
Diagnosis: A species of Hystrichokolpoma with large penitabular processes except those reflecting paraplates 6" and 1"'. The parasulcal and paracingular processes are not reflected.
Dimensions: Height: 40 (45) 50 µm; Width: 50 (58)72 µm, Processes: 30(37)40 µm. N=12.
Description: A species of Hystrichokolpoma with a smooth to faintly granulate periphragm. The endophragm is smooth apart from apical processes, fourteen processes are consistently present, twelve large and two smaller ones. The two smaller processes reflect paraplates 6"and 1"', whereas paraplates 2"', 3"' lack processes. The large processes are hollow, slightly fibrous and distally closed, denticulate and perforate. The archaeopyle is apical (tA). The operculum is free.
Discussion: Hystrichokolpoma reducta differs from all other Hystrichokolpoma species except Hystrichokolpoma pseudooceanicum Zevenboom and Santarelli, 1995 in the reduction or absence of paracingular and parasulcal processes. It differs from Hystrichokolpoma pseudooceanicum Zevenboom and Santarelli, 1995, by its much larger size and thicker wall and by possesing two types of processes instead of only one type. Hystrichokolpoma reducta is also similar to Dinocyst sp. D (Head et al., 1989b) but differs by having an apical archaeopyle rather than an epicystal one and by the consistent presence of the two smaller processes.
Occurences. Italy (this study, Powell, 1986b and Zevenboom et al., 1994 and Zevenboom in press, b, c).
Stratigraphic range: Latest Early Miocene (this study), see Fig. 5.