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Impagidinium variaseptum
Impagidinium variaseptum Marret and de Vernal, 1997, p.385,387, pl.3, figs.1-5.
Holotype: Marret and de Vernal, 1997, pl.3, figs.3-5.
Age: Holocene.
Original description (Marret and de Vernal, 1997)
Etymology: Latin, varia (variable) and septum (crest) in reference to the septa with variable height. Diagnosis: Proximate suturocavate cyst of subspherical shape. The cyst wall is thin, with a scabrate surface. Septa are more or less well-developed and are smooth to finely ornamented. The distal edge of the septa are indented, while the proximal apart overlay partially the paraplates. Boss is apical.,Paratabulation is of the gonyaulacacean type. Archeopyle is precingular. Operculum is absent.
Holotype: Plate III, 3-5, Slide E55-05, UQP: 3265/2. England Finder reference: 058. Repository: GEOTOP, Universite du Quebec a Montreal (Canada).
Dimensions: Holotype, central body 44 x 41 µm, height of septa 3 to 4.8 µm. Cyst body range 47 (57) 75 µm; height septa 3 to 11 µm. Number of specimens measured 21.
Description: The cyst is proximate, suturocavate, and subspherical. The cyst wall is usually thin (1µm), scabrate between crests and smooth to finely ornamented (including microgranulate) on orests. The septa are well-developed around the cyst body, and are of variable height. The distal edges of the sutures are stauromate. The broad bases of the septa are partially developed on the paraplates. Ornament on the sutural septa is coarser than that observed on the cyst membrane. Crests bear raised bosses in gonal and intergonal positions. Apical boss is present. Paratabulation is expressed by a sutural arrangement, of the gonyaulacacean type. Archeopyle is of type P The sulcus area is devoid of tabulation (see Plate III, 3).
Comparisons: I. variaseptum sp. nov. differs from other Impagidinium species by the unusual variabilityof the septa height over the cyst body and the presence of raised bosses on the sutural crests, in gonal and intergonal positions.
Remarks: Some specimens show a thicker wall layer (1.5 µm) and higher septa (12 µm), welldeveloped in the apical and antapical areas. The wall surface also is finely microgranulate and the cyst body is often bigger (65 to 75 pm) compared to those with lower septa.
Occurrence: Common in surface sediments of the southeastern Indian Ocean, west of Tasmania and southwestern Pacific Ocean, east of New Zealand (Sun and McMinn, 1994). 1. variaseptum sp. nov.,
however, seems to have an affinity for outer-neritic environments in contrast to the oceanic character of the other Impagidinium species.
Holotype: Marret and de Vernal, 1997, pl.3, figs.3-5.
Age: Holocene.
Original description (Marret and de Vernal, 1997)
Etymology: Latin, varia (variable) and septum (crest) in reference to the septa with variable height. Diagnosis: Proximate suturocavate cyst of subspherical shape. The cyst wall is thin, with a scabrate surface. Septa are more or less well-developed and are smooth to finely ornamented. The distal edge of the septa are indented, while the proximal apart overlay partially the paraplates. Boss is apical.,Paratabulation is of the gonyaulacacean type. Archeopyle is precingular. Operculum is absent.
Holotype: Plate III, 3-5, Slide E55-05, UQP: 3265/2. England Finder reference: 058. Repository: GEOTOP, Universite du Quebec a Montreal (Canada).
Dimensions: Holotype, central body 44 x 41 µm, height of septa 3 to 4.8 µm. Cyst body range 47 (57) 75 µm; height septa 3 to 11 µm. Number of specimens measured 21.
Description: The cyst is proximate, suturocavate, and subspherical. The cyst wall is usually thin (1µm), scabrate between crests and smooth to finely ornamented (including microgranulate) on orests. The septa are well-developed around the cyst body, and are of variable height. The distal edges of the sutures are stauromate. The broad bases of the septa are partially developed on the paraplates. Ornament on the sutural septa is coarser than that observed on the cyst membrane. Crests bear raised bosses in gonal and intergonal positions. Apical boss is present. Paratabulation is expressed by a sutural arrangement, of the gonyaulacacean type. Archeopyle is of type P The sulcus area is devoid of tabulation (see Plate III, 3).
Comparisons: I. variaseptum sp. nov. differs from other Impagidinium species by the unusual variabilityof the septa height over the cyst body and the presence of raised bosses on the sutural crests, in gonal and intergonal positions.
Remarks: Some specimens show a thicker wall layer (1.5 µm) and higher septa (12 µm), welldeveloped in the apical and antapical areas. The wall surface also is finely microgranulate and the cyst body is often bigger (65 to 75 pm) compared to those with lower septa.
Occurrence: Common in surface sediments of the southeastern Indian Ocean, west of Tasmania and southwestern Pacific Ocean, east of New Zealand (Sun and McMinn, 1994). 1. variaseptum sp. nov.,
however, seems to have an affinity for outer-neritic environments in contrast to the oceanic character of the other Impagidinium species.