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Batiacasphaera imperfecta
Batiacasphaera imperfecta, Stover and Helby, 1987
Holotype: Stover and Helby, 1987, fig.2A-B
Locus typicus: Perth Basin, W Australia
Stratum typicum: Barremian-Early Aptian
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Original description: [Stover and Helby, 1987, p. 261-262]:
Description:
Cysts proximate, subspherical to ellipsoidal with a moderately thick autophragm (about 2-2.5 µm).
Outer surface of autophragm composed of low, narrow, discontinuous ridges forming an imperfect reticulum with height and width generally less than 0.5 µm. Lumina circular to irregularly polygonal, varying in maximum diameter from less than 1 µm to 5 µm, most lumina 3 µm or less in diameter.
Archeopyle apical, type [tA], with zigzag principal suture; accessory sutures between precingular paraplates rarely present. Operculum free, large relative to cyst diameter, constituent paraplates not differentiated on opercular surface.
Paratabulation expressed by the archeopyle only, indications of a paracingulum and parasulcus absent.
Dimensions:
The measurements for 25 specimens without opercula are: length 34(44)54 µm, width 27(35)46 µm. Specimens with opercula are 8-13 µm longer.
Affinities:
Batiacasphaera imperfecta differs from B. reticulata (Davey) Davey 1979a in having an imperfect and somewhat larger meshed reticulum, an angular archeopyle margin, and a thicker autophragm. The average size of B. reticulata is greater than that of B. imperfecta, although the size ranges of the two species overlap.
Holotype: Stover and Helby, 1987, fig.2A-B
Locus typicus: Perth Basin, W Australia
Stratum typicum: Barremian-Early Aptian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Stover and Helby, 1987, p. 261-262]:
Description:
Cysts proximate, subspherical to ellipsoidal with a moderately thick autophragm (about 2-2.5 µm).
Outer surface of autophragm composed of low, narrow, discontinuous ridges forming an imperfect reticulum with height and width generally less than 0.5 µm. Lumina circular to irregularly polygonal, varying in maximum diameter from less than 1 µm to 5 µm, most lumina 3 µm or less in diameter.
Archeopyle apical, type [tA], with zigzag principal suture; accessory sutures between precingular paraplates rarely present. Operculum free, large relative to cyst diameter, constituent paraplates not differentiated on opercular surface.
Paratabulation expressed by the archeopyle only, indications of a paracingulum and parasulcus absent.
Dimensions:
The measurements for 25 specimens without opercula are: length 34(44)54 µm, width 27(35)46 µm. Specimens with opercula are 8-13 µm longer.
Affinities:
Batiacasphaera imperfecta differs from B. reticulata (Davey) Davey 1979a in having an imperfect and somewhat larger meshed reticulum, an angular archeopyle margin, and a thicker autophragm. The average size of B. reticulata is greater than that of B. imperfecta, although the size ranges of the two species overlap.