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Impagidinium agremon
Impagidinium agremon Willumsen, 2011, p.219–220, figs.9F,H,L; figs.10C–E.
Holotype: Willumsen, 2011, fig.9L.
Age: latest Maastrichtian–early Paleocene.
Original description (Willumsen, 2011):
Impagidinium agremon sp. nov. (Figs 9F, H, L; 10C–E)
Types. Holotype, Mead Stream, P30/f917, slide L18310/2, 6 mm, EF: S43,3 (Fig. 9L). Paratype 1, mid-Waipara River, M34/f195, slide L18330/3, 16 mm, EF: R34,1 (Fig. 9H). Paratype 2, mid-Waipara River, M34/f171, slide L14881/1, 16 mm, EF: H42,1/G42,3 (Fig. 9F)
Type unit and locality. Mead Hill Formation, Mead Stream section, Clarence Valley, Marlborough, New Zealand.
Etymology. Agremon (Greek) = net or open network refering to the reticulate surface ornamentation characteristic of this species.
Diagnosis. Circular Impagidinium cyst, with an intratabular reticulate ornamentation. Sutural septa are hyaline, low to medium height and with prominent gonal septa Operculum generally detached.
Description. A medium-sized, circular cyst with ca 4–8 µm high hyaline sutural septa. The septa are more prominent in the gonal positions. Intratabular areas are ornamented with a low, irregular reticulum (Figs 9, F–L; 10C–E). Muri are ca 0.5–1.0 µm high and form crests between the gonal areas. The lumina of the reticulum have a diameter of ca 2–3 µm. Tabulation in the sulcal area was not observed. Total diameter 57(63) 70 µm [5 specimens]. Septa 4(5)8 µm high [5 specimens measured]. Cingulum 3 µm wide [2 specimens measured]. Lumina in the reticulum 2(3)3 µm in diameter [4 specimens measured].
Remarks. Impagidinium agremon sp. nov. differs from I. maculatum Cookson & Eisenack, 1961, I. pentahedrias Damassa, 1979 and I. elegans Cookson & Eisenack, 1965 in having a regular reticulate granulate surface ornamentation, rather than a ‘dotted’ or granulate surface; I. agremon differs from I. cassiculus Wilson, 1988 by having an intratabular, reticulate surface and lacking a membranous apical horn; I. agremon differs from I. parvireticulatum Wilson, 1988 by its intratabular reticulate surface ornamentation and parasutural septa with an even crest; and from I. maghribensis Slimani, 2007 by its intratabular, reticulate surface, relatively more expanded sutural septa and larger size. In a previous palynological study of samples from Mead Stream, Wilson recorded and illustrated this species as Impagidinium sp. (Strong et al. 1995, fig. 13.11, 13.12).
Age and distribution. The FO of Impagidinium agremon was not observed in the sampled interval and it occurs throughout the uppermost Maastrichtian. Its LO is within the lower Paleocene strata assigned to the uppermost part of radiolarian Zone RP2 (Hollis et al. 2003b); it is common to rare. It was recorded from: Angora Stream, Branch Stream, Chancet Rocks, Fairfield Quarry, Grey River, Mead Stream, midWaipara River, Tawanui Stream, Wharanui Point and Woodside Creek. Schiøler (in Laird et al. 2003) also recorded this species in sections from Tora, southeast Wairarapa, New Zealand.
Holotype: Willumsen, 2011, fig.9L.
Age: latest Maastrichtian–early Paleocene.
Original description (Willumsen, 2011):
Impagidinium agremon sp. nov. (Figs 9F, H, L; 10C–E)
Types. Holotype, Mead Stream, P30/f917, slide L18310/2, 6 mm, EF: S43,3 (Fig. 9L). Paratype 1, mid-Waipara River, M34/f195, slide L18330/3, 16 mm, EF: R34,1 (Fig. 9H). Paratype 2, mid-Waipara River, M34/f171, slide L14881/1, 16 mm, EF: H42,1/G42,3 (Fig. 9F)
Type unit and locality. Mead Hill Formation, Mead Stream section, Clarence Valley, Marlborough, New Zealand.
Etymology. Agremon (Greek) = net or open network refering to the reticulate surface ornamentation characteristic of this species.
Diagnosis. Circular Impagidinium cyst, with an intratabular reticulate ornamentation. Sutural septa are hyaline, low to medium height and with prominent gonal septa Operculum generally detached.
Description. A medium-sized, circular cyst with ca 4–8 µm high hyaline sutural septa. The septa are more prominent in the gonal positions. Intratabular areas are ornamented with a low, irregular reticulum (Figs 9, F–L; 10C–E). Muri are ca 0.5–1.0 µm high and form crests between the gonal areas. The lumina of the reticulum have a diameter of ca 2–3 µm. Tabulation in the sulcal area was not observed. Total diameter 57(63) 70 µm [5 specimens]. Septa 4(5)8 µm high [5 specimens measured]. Cingulum 3 µm wide [2 specimens measured]. Lumina in the reticulum 2(3)3 µm in diameter [4 specimens measured].
Remarks. Impagidinium agremon sp. nov. differs from I. maculatum Cookson & Eisenack, 1961, I. pentahedrias Damassa, 1979 and I. elegans Cookson & Eisenack, 1965 in having a regular reticulate granulate surface ornamentation, rather than a ‘dotted’ or granulate surface; I. agremon differs from I. cassiculus Wilson, 1988 by having an intratabular, reticulate surface and lacking a membranous apical horn; I. agremon differs from I. parvireticulatum Wilson, 1988 by its intratabular reticulate surface ornamentation and parasutural septa with an even crest; and from I. maghribensis Slimani, 2007 by its intratabular, reticulate surface, relatively more expanded sutural septa and larger size. In a previous palynological study of samples from Mead Stream, Wilson recorded and illustrated this species as Impagidinium sp. (Strong et al. 1995, fig. 13.11, 13.12).
Age and distribution. The FO of Impagidinium agremon was not observed in the sampled interval and it occurs throughout the uppermost Maastrichtian. Its LO is within the lower Paleocene strata assigned to the uppermost part of radiolarian Zone RP2 (Hollis et al. 2003b); it is common to rare. It was recorded from: Angora Stream, Branch Stream, Chancet Rocks, Fairfield Quarry, Grey River, Mead Stream, midWaipara River, Tawanui Stream, Wharanui Point and Woodside Creek. Schiøler (in Laird et al. 2003) also recorded this species in sections from Tora, southeast Wairarapa, New Zealand.