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Apteodinium vescum
From Fensome et al., 2019:
Apteodinium? vescum Matsuoka, 1983b, p.139, pl.5, figs.7–8. Holotype: Matsuoka, 1983b, pl.5, fig.7; Jan du Chêne et al., 1986a, pl.12, fig.7. Originally Apteodinium, subsequently (and now) Apteodinium?. Questionable assignment:
Lucas-Clark (1987, p.180). Age: Early-Middle Miocene.
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Original description: [Matsuoka, 1983b]:
Apteodinium vescum sp. nov.
PI. 5, figs. 7-8
Derivation of name: Latin, vescus, thin, with reference to the thin cyst wall.
Diagnosis: Spherical to rounded pentagonal cyst with apical projection. Smooth autophragm without any ornamentation. Both paracingulum and parasulcus not indicated by any feature. Archeopyle probably precingular and formed by loss of the 3" paraplate. Paratabulation not observed.
Holotype: KMD slide NNA 3-5 (16.3/127.2), pl. 5, fig. 7. Sample NNA 3, Shimoseki Formation equivalent to the Nanatani Formation - late Early-to-early Middle Miocene. Loc.: Matsuoka, Shibata City, Nigata Prefecture, Central Japan.
Description: The intermediate proximate cyst is spherical to rounded pentagonal and consists of one layer, autophragm. The epicyst has a small conical projection at the apex. Any ornamentation indicating paraplates, paracingulum and parasulcus is not developed. There are a few small and thicked areas with circular outline surrounded by a "halo iust like as Apteodinium maculatum. The trapezoidal archeopyle may indicate
precingular type and may be derived from loss of the 3" paraplate. In a few specimens, the operculum is sill
attached on the dorsal area.
Dimensions: Holotype: Length of cyst 89.5 μm, width of cyst 89.5 μm, length of apical projection 5.2 μm.
Other specimens: Length of cyst 56-90 μm, width of cyst 60-90 μm, length of apical projection 3.7-5.2 μm.
Occurrence: Rare in the Nanatani Formation and its equivalent formations (ate Early-to-early Midle Miocene).
Remarks: Apteodinium vescum sp. nov. differs from A. maculatum in having a smooth autophragm and from modern Protoperidinium cysts in probably possessing a precingular archeopyle.
Apteodinium? vescum Matsuoka, 1983b, p.139, pl.5, figs.7–8. Holotype: Matsuoka, 1983b, pl.5, fig.7; Jan du Chêne et al., 1986a, pl.12, fig.7. Originally Apteodinium, subsequently (and now) Apteodinium?. Questionable assignment:
Lucas-Clark (1987, p.180). Age: Early-Middle Miocene.
---------------------------------------------------------------------------------------------------
Original description: [Matsuoka, 1983b]:
Apteodinium vescum sp. nov.
PI. 5, figs. 7-8
Derivation of name: Latin, vescus, thin, with reference to the thin cyst wall.
Diagnosis: Spherical to rounded pentagonal cyst with apical projection. Smooth autophragm without any ornamentation. Both paracingulum and parasulcus not indicated by any feature. Archeopyle probably precingular and formed by loss of the 3" paraplate. Paratabulation not observed.
Holotype: KMD slide NNA 3-5 (16.3/127.2), pl. 5, fig. 7. Sample NNA 3, Shimoseki Formation equivalent to the Nanatani Formation - late Early-to-early Middle Miocene. Loc.: Matsuoka, Shibata City, Nigata Prefecture, Central Japan.
Description: The intermediate proximate cyst is spherical to rounded pentagonal and consists of one layer, autophragm. The epicyst has a small conical projection at the apex. Any ornamentation indicating paraplates, paracingulum and parasulcus is not developed. There are a few small and thicked areas with circular outline surrounded by a "halo iust like as Apteodinium maculatum. The trapezoidal archeopyle may indicate
precingular type and may be derived from loss of the 3" paraplate. In a few specimens, the operculum is sill
attached on the dorsal area.
Dimensions: Holotype: Length of cyst 89.5 μm, width of cyst 89.5 μm, length of apical projection 5.2 μm.
Other specimens: Length of cyst 56-90 μm, width of cyst 60-90 μm, length of apical projection 3.7-5.2 μm.
Occurrence: Rare in the Nanatani Formation and its equivalent formations (ate Early-to-early Midle Miocene).
Remarks: Apteodinium vescum sp. nov. differs from A. maculatum in having a smooth autophragm and from modern Protoperidinium cysts in probably possessing a precingular archeopyle.