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Impagidinium cavea
Impagidinium cavea Willumsen, 2011, p.219, figs.9G,J,K; figs.10F–H.
Holotype: Willumsen, 2011, fig.9K.
Age: latest Maastrichtian–early Paleocene.
Original decsription (Willumsen, 2011):
Impagidinium cavea sp. nov. (Figs 9G, J, K; 10F–H)
Types. Holotype, Mead Stream, P30/f955, L18739, SM4781, EF: (P36,4), (Figs 9K). Paratype 1, Grey River, M34/f275, L18275/ 3, SM4782, EF: (N46,3), (Fig. 9G, J). Paratype 2, Mead Stream, P30/f911, SEM stub (Fig. 10F–H).
Type unit and locality. Mead Hill Formation, Mead Stream section, Clarence Valley, Marlborough, New Zealand.
Etymology. Cavea (Latin)¼a hollow place with reference to the prominent hollow and gonal parasutural septa distinctive of this Impagidinium species.
Diagnosis. Suturocavate, circular to oval Impagidinium cyst with prominent, perforated hyaline parasutural septa. The sutural septa increase to almost twice their height in the gonal area. Gonal crests are hollow.
Description. Small- to medium-sized suturocavate cyst, circular to oval with prominent sutural hyaline septa that are 4–8 µm high. Gonally, the septa are hollow and expanded. Intergonal crests are perforated by a few, ca 0.5–1 µm wide circular holes (Fig. 10G–H). The cingulum is 6 µm wide. Archeopyle is precingular formed by loss of plate 3’’. The operculum is free. Total diameter 65(69)79 µm [5 specimens measured]. Septa 7(8)8 µm high [5 specimens measured]. Cingulum 6 µm wide [1 specimen measured].
Remarks. Impagidinium cavea sp. nov. differs from other species of this genus by having hollow septa in the gonal areas and a few perforations in the intergonal septa. Impagidinium cavea has distally pointed projections at gonal positions similar to ‘Hystrichosphaera cingulata’ illustrated by Wilson (1967, p. 68, fig. 36). Crouch (1993, p. 69) also illustrated a similar cyst under the name Impagidinium spp. ovum.
Age and distribution. The FO of Impagidinium cavea is below the sampled sections. The species occurs throughout the uppermost Maastrichtian strata where it is rare to common. Impagidinium cavea has its LO in the middle to upper part of the lower Paleocene radiolarian zone RP2 and was recorded in sections at Branch Stream, Grey River, Fairfield Quarry, Mead Stream and Wharanui Point.
Holotype: Willumsen, 2011, fig.9K.
Age: latest Maastrichtian–early Paleocene.
Original decsription (Willumsen, 2011):
Impagidinium cavea sp. nov. (Figs 9G, J, K; 10F–H)
Types. Holotype, Mead Stream, P30/f955, L18739, SM4781, EF: (P36,4), (Figs 9K). Paratype 1, Grey River, M34/f275, L18275/ 3, SM4782, EF: (N46,3), (Fig. 9G, J). Paratype 2, Mead Stream, P30/f911, SEM stub (Fig. 10F–H).
Type unit and locality. Mead Hill Formation, Mead Stream section, Clarence Valley, Marlborough, New Zealand.
Etymology. Cavea (Latin)¼a hollow place with reference to the prominent hollow and gonal parasutural septa distinctive of this Impagidinium species.
Diagnosis. Suturocavate, circular to oval Impagidinium cyst with prominent, perforated hyaline parasutural septa. The sutural septa increase to almost twice their height in the gonal area. Gonal crests are hollow.
Description. Small- to medium-sized suturocavate cyst, circular to oval with prominent sutural hyaline septa that are 4–8 µm high. Gonally, the septa are hollow and expanded. Intergonal crests are perforated by a few, ca 0.5–1 µm wide circular holes (Fig. 10G–H). The cingulum is 6 µm wide. Archeopyle is precingular formed by loss of plate 3’’. The operculum is free. Total diameter 65(69)79 µm [5 specimens measured]. Septa 7(8)8 µm high [5 specimens measured]. Cingulum 6 µm wide [1 specimen measured].
Remarks. Impagidinium cavea sp. nov. differs from other species of this genus by having hollow septa in the gonal areas and a few perforations in the intergonal septa. Impagidinium cavea has distally pointed projections at gonal positions similar to ‘Hystrichosphaera cingulata’ illustrated by Wilson (1967, p. 68, fig. 36). Crouch (1993, p. 69) also illustrated a similar cyst under the name Impagidinium spp. ovum.
Age and distribution. The FO of Impagidinium cavea is below the sampled sections. The species occurs throughout the uppermost Maastrichtian strata where it is rare to common. Impagidinium cavea has its LO in the middle to upper part of the lower Paleocene radiolarian zone RP2 and was recorded in sections at Branch Stream, Grey River, Fairfield Quarry, Mead Stream and Wharanui Point.