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Nematosphaeropsis major
Nematosphaeropsis major Head et al., 1989
Holotype: Head et al., 1989, pl.2, figs.1-2
Age: Late Miocene
Original description (Head et al., 1989):
Nematosphaeropsis major n. sp. (Pl. 2, Figs. 1-4)
Holotype. Plate 2, Figures 1, 2; Sample 105-646B-80X-2, 2-4 cm; (1) Q13/1.
Derivation of name. Latin major, with respect to the large size of this species.
Diagnosis. Cysts large, chorate and trabeculate with spherical to subspherical central body and hollow processes that are distally trifurcate (and bifurcate?); each branch supports a pair of narrow, parallel, ribbon-like trabeculae. Wall surface is almost smooth to faintly granulate. Archeopyle precingular Type P (presumably Type Py). Operculum free.
Dimensions. Holotype: central body maximum diameter, 50 µm; overall diameter, 87 µm. Range, maximum central body diameter, 44(50.9)63 yum, overall diameter, 74(81.7)91 µm. Width of trabeculae, 1.0-2.5 µm. Twelve specimens were measured.
Description. Processes are gonal and possibly intergonal. Paratabulation could not be determined, owing to compression of specimens, although appears to be gonyaulacacean and typical for the genus Nematosphaeropsis. The wall surface is commonly faintly granulate. The granules are slightly raised, usually discrete, rounded cushions of 1 µm or less in diameter; this morphology is best observed under interference contrast microscopy. The archeopyle is precingular and presumably formed by detachment of paraplate 3".
Discussion. This species is distinguished by its large size and narrow ribbon-like trabeculae. N. lemniscata Bujak, 1984 is much smaller, with an apparently denser network of trabeculae (presumably due to a greater number of intergonal processes). Both species were present in the same samples and could be readily differentiated. TV. downii Brown, 1986 is similar in size and possibly also in body surface ornament. It differs (1) in having broader trabeculae, which occur as parallel pairs "linked by a thin membrane" (Brown, 1986, p. 7); and (2) in the occasional presence of parasutural features on the cyst wall, which were not observed for N. major n. sp.
Holotype: Head et al., 1989, pl.2, figs.1-2
Age: Late Miocene
Original description (Head et al., 1989):
Nematosphaeropsis major n. sp. (Pl. 2, Figs. 1-4)
Holotype. Plate 2, Figures 1, 2; Sample 105-646B-80X-2, 2-4 cm; (1) Q13/1.
Derivation of name. Latin major, with respect to the large size of this species.
Diagnosis. Cysts large, chorate and trabeculate with spherical to subspherical central body and hollow processes that are distally trifurcate (and bifurcate?); each branch supports a pair of narrow, parallel, ribbon-like trabeculae. Wall surface is almost smooth to faintly granulate. Archeopyle precingular Type P (presumably Type Py). Operculum free.
Dimensions. Holotype: central body maximum diameter, 50 µm; overall diameter, 87 µm. Range, maximum central body diameter, 44(50.9)63 yum, overall diameter, 74(81.7)91 µm. Width of trabeculae, 1.0-2.5 µm. Twelve specimens were measured.
Description. Processes are gonal and possibly intergonal. Paratabulation could not be determined, owing to compression of specimens, although appears to be gonyaulacacean and typical for the genus Nematosphaeropsis. The wall surface is commonly faintly granulate. The granules are slightly raised, usually discrete, rounded cushions of 1 µm or less in diameter; this morphology is best observed under interference contrast microscopy. The archeopyle is precingular and presumably formed by detachment of paraplate 3".
Discussion. This species is distinguished by its large size and narrow ribbon-like trabeculae. N. lemniscata Bujak, 1984 is much smaller, with an apparently denser network of trabeculae (presumably due to a greater number of intergonal processes). Both species were present in the same samples and could be readily differentiated. TV. downii Brown, 1986 is similar in size and possibly also in body surface ornament. It differs (1) in having broader trabeculae, which occur as parallel pairs "linked by a thin membrane" (Brown, 1986, p. 7); and (2) in the occasional presence of parasutural features on the cyst wall, which were not observed for N. major n. sp.