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Alterbia microgranulata
Alterbia microgranulata, (Stanley, 1965), Lentin and Williams, 1976
Combination illegitimate: the generic name Alterbia is illegitimate.
Holotype: Stanley, 1965, pl.19, figs.4-5
Locus typicus: South Dakota, USA
Stratum typicum: Paleocene
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Original description as Deflandrea microgranulata: [Stanley, 1965, p. 219]:
Description:
Outer cyst subcircular in dorso-ventral view;
length 54-57 µm, width 45-48 µm;
outer cyst wall smooth and thin.
Apical horn conically shaped, length about 7 µm; apical horn appears to bear a pore at its distal end. Antapical horns unequal in length with left one being short (about 5 µm in length), whereas the right one is only slightly developed.
Inner cyst completely fills outer cyst, pentagonally shaped with the postelior end flattened;
small granulations with a diameter of about 0.3 µm ornament the membrane of the inner cyst.
Girdle characterized by a wide band that is well developed on the dorsal side and blends into the furrow on the ventral side.
Archeopyle often distinct with the anterior and posterior sides being about equal in length.
Affinities:
Deflandrea microgranulata, closely resembles D. ventriosa Alberti, 1959. The only difference that could be determined from Alberti's description and illustration is that D. microgranulata has a slightly smaller size and the apical horn bears a distal pore.
Combination illegitimate: the generic name Alterbia is illegitimate.
Holotype: Stanley, 1965, pl.19, figs.4-5
Locus typicus: South Dakota, USA
Stratum typicum: Paleocene
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Original description as Deflandrea microgranulata: [Stanley, 1965, p. 219]:
Description:
Outer cyst subcircular in dorso-ventral view;
length 54-57 µm, width 45-48 µm;
outer cyst wall smooth and thin.
Apical horn conically shaped, length about 7 µm; apical horn appears to bear a pore at its distal end. Antapical horns unequal in length with left one being short (about 5 µm in length), whereas the right one is only slightly developed.
Inner cyst completely fills outer cyst, pentagonally shaped with the postelior end flattened;
small granulations with a diameter of about 0.3 µm ornament the membrane of the inner cyst.
Girdle characterized by a wide band that is well developed on the dorsal side and blends into the furrow on the ventral side.
Archeopyle often distinct with the anterior and posterior sides being about equal in length.
Affinities:
Deflandrea microgranulata, closely resembles D. ventriosa Alberti, 1959. The only difference that could be determined from Alberti's description and illustration is that D. microgranulata has a slightly smaller size and the apical horn bears a distal pore.