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Impagidinium tectum
Impagidinium tectum Biffi and Manum, 1988
Holotype: Biffi and Manum, 1988, pl.12, fig.3-4
Locus typicus: Ca" Tosi Section, Marche Region, Central Italy
Stratum typicum: Late Oligocene-Early Miocene
Original diagnosis: Biffi and manum 1988, p. 207: Impagidinium tectum
Proximate cyst of ovoid to subphaerical shape, epicyst and hypocyst of approximately equal size. Cyst wall slightly more than 1 µm thick; thin outer and inner layers separated by a columellar layer. Wall in surface view microreticulate to finely pitted. Parasutural septa formed by outermost wall layer, paratabulation formula 4", 6", 6c, 5"", lp, 1"", ps. Paraplate 6" small and subtriangular, its contact with 4" very short. Paraplates 1" and 4" of almost equal size and narrowly elongate shape, allowing 1" and 5" to extend almost to the apex. Sulcal area not subdivided.
Dimensions -- Holotype: cyst length 70 µm; breadth 44 µm septa included (3-5 µm). Mean values (bracketed) and extremes (n = 25): cyst length 46(55)72 µm; breadth 40(49)64 µm.
Original description: Biffi and manum 1988, p. 207: Impagidinium tectum
Parasutural septa appear to be formed by twin layers of the outermost cyst wall layer; they lack the microreticulate pattern seen in the cyst wall, but may appear sparsely pitted. The double-layered nature of the septa is evident from a median line seen along their bases in surface view of the cyst wall, and also, from septal junctions in ambital view. The two layers leave no appreciable parasutural pericoel between them except occasionally at parasutural junctions, especially along the cingulum. The sulcus is not subdivided (Pl. 12, fig. 3).
Remarks: Biffi and manum 1988, p. 207
This species resembles Leptodinium italicum n. sp. in overall morphology and size; Leptodinium italicum n. sp. has a periphragm of spongy nature as opposed to columellar in the present species, plus a distinct apical horn and very high crests. Impagidinium tectum n. sp. differs from I. gibrensis Michoux in having the sulcal area not subdivided and a microreticulate surface. The presence of an apical boss and the sulcal paratabulation completely expressed separate I. sphaericum (Wall) from our new species; Impagidinium dispertitum (Cookson & Eisenack) appears related but the structure and characteristic stratification of the wall clearly distinguishes our species.
Occurrences:
Monte ConeroSR 992 - SR 995 rare
Ca" FusconiPAL 103 - PAL lOG rare to common
Montebello d"UrbinoPAL 114 - PAL 133 common
Ca" Tosi PAL201 - PAL 214 commontoabundant
Holotype: Biffi and Manum, 1988, pl.12, fig.3-4
Locus typicus: Ca" Tosi Section, Marche Region, Central Italy
Stratum typicum: Late Oligocene-Early Miocene
Original diagnosis: Biffi and manum 1988, p. 207: Impagidinium tectum
Proximate cyst of ovoid to subphaerical shape, epicyst and hypocyst of approximately equal size. Cyst wall slightly more than 1 µm thick; thin outer and inner layers separated by a columellar layer. Wall in surface view microreticulate to finely pitted. Parasutural septa formed by outermost wall layer, paratabulation formula 4", 6", 6c, 5"", lp, 1"", ps. Paraplate 6" small and subtriangular, its contact with 4" very short. Paraplates 1" and 4" of almost equal size and narrowly elongate shape, allowing 1" and 5" to extend almost to the apex. Sulcal area not subdivided.
Dimensions -- Holotype: cyst length 70 µm; breadth 44 µm septa included (3-5 µm). Mean values (bracketed) and extremes (n = 25): cyst length 46(55)72 µm; breadth 40(49)64 µm.
Original description: Biffi and manum 1988, p. 207: Impagidinium tectum
Parasutural septa appear to be formed by twin layers of the outermost cyst wall layer; they lack the microreticulate pattern seen in the cyst wall, but may appear sparsely pitted. The double-layered nature of the septa is evident from a median line seen along their bases in surface view of the cyst wall, and also, from septal junctions in ambital view. The two layers leave no appreciable parasutural pericoel between them except occasionally at parasutural junctions, especially along the cingulum. The sulcus is not subdivided (Pl. 12, fig. 3).
Remarks: Biffi and manum 1988, p. 207
This species resembles Leptodinium italicum n. sp. in overall morphology and size; Leptodinium italicum n. sp. has a periphragm of spongy nature as opposed to columellar in the present species, plus a distinct apical horn and very high crests. Impagidinium tectum n. sp. differs from I. gibrensis Michoux in having the sulcal area not subdivided and a microreticulate surface. The presence of an apical boss and the sulcal paratabulation completely expressed separate I. sphaericum (Wall) from our new species; Impagidinium dispertitum (Cookson & Eisenack) appears related but the structure and characteristic stratification of the wall clearly distinguishes our species.
Occurrences:
Monte ConeroSR 992 - SR 995 rare
Ca" FusconiPAL 103 - PAL lOG rare to common
Montebello d"UrbinoPAL 114 - PAL 133 common
Ca" Tosi PAL201 - PAL 214 commontoabundant