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Impagidinium aspinatum
Impagidinium aspinatum (Cookson and Eisenack, 1974) Damassa, 1979
Originally Spiniferites cornutus var. aspinatus, subsequently Spiniferites cornutus subsp. aspinatus, thirdly (and now) Impagidinium aspinatum.
Holotype: Cookson and Eisenack 1974, pl.23, fig.6
Locus typicus: Rivernook Bed, SW Victoria, Australia
Stratum typicum: Paleocene
Translation Cookson and Eisenack, 1974: GSC, courtesy R. Fensome
Original diagnosis: Cookson and Eisenack, 1974, p. 63: Spiniferites cornutus ssp. aspinatus
Shell oval, apical horn relatively short, yet fairly broad with blunt tip. Processes missing. Field-boundaries and girdle demarcated by low lists. Longitudinal furrow extending downwardly almost in a straight-lined manner. Girdle highly helicoidal, its extremities ventrally displaced by about one
furrow-width. Surface distinctly granular.
Dimensions: shell about 74 x 57 µm, overall 88 x 65 µm; horn about 15 µm, list-height 4-5 µm. One specimen ; Rivernook Bed, Paleocene.
Supplemental diagnosis: Damassa, 1979, p. 826
Proximate cyst having a rather coarsely granulate wall. Parasutural septa indicate paratabulation; septa betu een apical paraplates 1"/2", 2"/3", and 3"/4" are fused and extended into a three-bladed horn.
Description: Damassa, 1979, p. 826:
Proximate cyst, ellipsoidal, autophragm with a total thickness of about 2 µm. Length, 53-65 µm (mean = 59 µm, of 11 specimens). Equatorial diameter 40-54 µm (mean = 46 µm, of 11 specimens). Parasutural septa about 2-8 µm in height (mean = 59µm, of 13 specimens), except the septa between apical paraplates 1"/2", 2"/3", 3"/4" which are fused and extended into a threebladed horn 12-28 µm long (mean = 20 µm, of 8 specimens). Septum 1"/4" ends below the apex of the cyst. No antapical horn is present. Surface of cyst ornamented uith rather coarse granules about 1 µm in diameter. Ends of paracingulum strongly offset, separated by about 1.5 times the width of the paracingulum. Paratabulation on the ventral surface incompleteIy developed; the posterior sulcal, posterior intercalary and first postcingular paraplates are partially or completely delineated by septa, the remaining sulcal paraplates are not distinguished. Sixth precingular paraplate triangular in outline, smaller than 1"-5". Archeopyle formed by loss of the third precingular paraplate, pentagonal in outline. Operculum free. Paratabulation. 4", 6", 6c, 1p, ps, 5-6""", 1"""". Inferred thecal tabulation. 4", 6", 6c, 1p, 5s, 6""", 1"""".
Remarks: Cookson and Eisenack, 1974, p. 63: Spiniferites cornutus ssp. aspinatus
The specimen is slightly polyhedrally deformed. The horn is three-sided, since 3 lists are involved. Its lower portion has almost parallel edges, the upper third portion is conical. It appears to be solid. The absence of the processes represents a parallel case to the Sp. cingulatus.
Originally Spiniferites cornutus var. aspinatus, subsequently Spiniferites cornutus subsp. aspinatus, thirdly (and now) Impagidinium aspinatum.
Holotype: Cookson and Eisenack 1974, pl.23, fig.6
Locus typicus: Rivernook Bed, SW Victoria, Australia
Stratum typicum: Paleocene
Translation Cookson and Eisenack, 1974: GSC, courtesy R. Fensome
Original diagnosis: Cookson and Eisenack, 1974, p. 63: Spiniferites cornutus ssp. aspinatus
Shell oval, apical horn relatively short, yet fairly broad with blunt tip. Processes missing. Field-boundaries and girdle demarcated by low lists. Longitudinal furrow extending downwardly almost in a straight-lined manner. Girdle highly helicoidal, its extremities ventrally displaced by about one
furrow-width. Surface distinctly granular.
Dimensions: shell about 74 x 57 µm, overall 88 x 65 µm; horn about 15 µm, list-height 4-5 µm. One specimen ; Rivernook Bed, Paleocene.
Supplemental diagnosis: Damassa, 1979, p. 826
Proximate cyst having a rather coarsely granulate wall. Parasutural septa indicate paratabulation; septa betu een apical paraplates 1"/2", 2"/3", and 3"/4" are fused and extended into a three-bladed horn.
Description: Damassa, 1979, p. 826:
Proximate cyst, ellipsoidal, autophragm with a total thickness of about 2 µm. Length, 53-65 µm (mean = 59 µm, of 11 specimens). Equatorial diameter 40-54 µm (mean = 46 µm, of 11 specimens). Parasutural septa about 2-8 µm in height (mean = 59µm, of 13 specimens), except the septa between apical paraplates 1"/2", 2"/3", 3"/4" which are fused and extended into a threebladed horn 12-28 µm long (mean = 20 µm, of 8 specimens). Septum 1"/4" ends below the apex of the cyst. No antapical horn is present. Surface of cyst ornamented uith rather coarse granules about 1 µm in diameter. Ends of paracingulum strongly offset, separated by about 1.5 times the width of the paracingulum. Paratabulation on the ventral surface incompleteIy developed; the posterior sulcal, posterior intercalary and first postcingular paraplates are partially or completely delineated by septa, the remaining sulcal paraplates are not distinguished. Sixth precingular paraplate triangular in outline, smaller than 1"-5". Archeopyle formed by loss of the third precingular paraplate, pentagonal in outline. Operculum free. Paratabulation. 4", 6", 6c, 1p, ps, 5-6""", 1"""". Inferred thecal tabulation. 4", 6", 6c, 1p, 5s, 6""", 1"""".
Remarks: Cookson and Eisenack, 1974, p. 63: Spiniferites cornutus ssp. aspinatus
The specimen is slightly polyhedrally deformed. The horn is three-sided, since 3 lists are involved. Its lower portion has almost parallel edges, the upper third portion is conical. It appears to be solid. The absence of the processes represents a parallel case to the Sp. cingulatus.