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Apteodinium ellipticum
Apteodinium ellipticum, He Chengquan et al. 2005a, p. 246–247; pl.19, figs.1–7.
Holotype: He Chengquan et al. 2005a, pl.19, fig.2.
Occurrence: Comparative abundant in the upper part of the Biqu Formation and rare in the base of the Xueshan Formation, Qoimaco section, Tanggulashan Townshop, Golmud, Qinghai
Age: Late Jurassic.
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Original description: [He Chengquan et al., 2005a]:
Description:
Cyst proximate, dorso-vertally compressed, ellipsoidal to roundly rhomboidal in outline, length greater than width. Epicyst and hypocyst nearly equal in length, semicircular or arched. Apex and antapex broadly rounded, without apical or antapical horns. Paracingulum usually narrower, about 3.5 µm ± wide, occasionally 4.8 µm wide. Parasulcus indicated more or less, outline comparatively indistinct. Autophragm about 1 µm thick, or apposed of compressed inner and outer layers, surface densely granular to granular-rugate; some granules higher, denticulate at some part of outline. Surface of several specimens seems granular to punctate. No parasutural feature except paracingulum.
Paratabulation indicted by archeopyle and paracingulum.
Archeopyle precingular, Type P (3’’). Operculum free.
Dimensions (µm):
Cyst 40-52 long, 35.5-48.9 wide; holotype 47 long, 42 wide.
Affinities/Comments:
The new species resembles Late Cretaceous Apteodinium sparsum or Eocene A. granorugosum and A. tenuicinctum in shape and ornamentation, all of which lack apical and antapical protrusion and have similar ornamentation. But the new species id different in a smaller cyst, ellipsoidal but not spherical outline, thicker wall, developed ornamentation (higher granular-rugae, denticulate at some part of outline), and a narrow and nearly planar paracinulum. A. granorugosum has high paracingular ridges, a thin autophragm, thin and weak granule; A. sparsum has a broad paracingulum and high parallel transverse equatorial ridges, a thin autophragm and short rugae with few granules; A. tenuicinctum has a thin autophragm, thin and weak granules, and no parasulcus.
Holotype: He Chengquan et al. 2005a, pl.19, fig.2.
Occurrence: Comparative abundant in the upper part of the Biqu Formation and rare in the base of the Xueshan Formation, Qoimaco section, Tanggulashan Townshop, Golmud, Qinghai
Age: Late Jurassic.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [He Chengquan et al., 2005a]:
Description:
Cyst proximate, dorso-vertally compressed, ellipsoidal to roundly rhomboidal in outline, length greater than width. Epicyst and hypocyst nearly equal in length, semicircular or arched. Apex and antapex broadly rounded, without apical or antapical horns. Paracingulum usually narrower, about 3.5 µm ± wide, occasionally 4.8 µm wide. Parasulcus indicated more or less, outline comparatively indistinct. Autophragm about 1 µm thick, or apposed of compressed inner and outer layers, surface densely granular to granular-rugate; some granules higher, denticulate at some part of outline. Surface of several specimens seems granular to punctate. No parasutural feature except paracingulum.
Paratabulation indicted by archeopyle and paracingulum.
Archeopyle precingular, Type P (3’’). Operculum free.
Dimensions (µm):
Cyst 40-52 long, 35.5-48.9 wide; holotype 47 long, 42 wide.
Affinities/Comments:
The new species resembles Late Cretaceous Apteodinium sparsum or Eocene A. granorugosum and A. tenuicinctum in shape and ornamentation, all of which lack apical and antapical protrusion and have similar ornamentation. But the new species id different in a smaller cyst, ellipsoidal but not spherical outline, thicker wall, developed ornamentation (higher granular-rugae, denticulate at some part of outline), and a narrow and nearly planar paracinulum. A. granorugosum has high paracingular ridges, a thin autophragm, thin and weak granule; A. sparsum has a broad paracingulum and high parallel transverse equatorial ridges, a thin autophragm and short rugae with few granules; A. tenuicinctum has a thin autophragm, thin and weak granules, and no parasulcus.