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Quadrina condita
Quadrina? condita De Verteuil and Norris, 1992
Acritarch
De Verteuil and Norris, 1992 questionably included this species in Quadrina and regarded it as algae incertae sedis.
Holotype: De Verteuil and Norris, 1992, pl.6, fig.7
Locus typicus: St. Leonard Member ("Bed 18") of Choptank Fm, Scientists Cliffs, Chesapeake Bay, Calvert County, Maryland, U.S.A.
Stratum typicum: Late-middle Miocene
Original diagnosis: De Verteuil and Norris, 1992, p.420
Intermediate, pigmented, organic-walled microfossil with a rectangular, square or cruciform outline when compressed. The four corners or lobes each bear a cluster of approximately 8-20 hollow, tapered, and acuminate or capitate processes that are arranged in imperfect circular bands about the lobes. The processes are approximately 30-50% of vesicle diameter in length and appear to communicate with the internal cavity. All other areas are without processes. The wall appears autophragmal and is psilate to irregularly microgranulose. An excystment aperture is present but rarely discernable; it appears to be asymmetrically positioned with respect to the plane of bilateral symmetry passing between the process clusters, being partly within an area of process development.
Dimensions. As oriented in discussion: Apical/antapical height, 25(32)50 µm; holotype, 40 µm. Equatorial diameter, 25(33)52 µm; holotype, 42 µm. Processes, 8-23 µm; holotype, 10-13 µm. Fifteen specimens measured.
Affinities:
De Verteuil and Norris, 1992, p. 423: Quadrina? condita differs from Selenopemphix quanta and other spinate species of Selenopemphix in the clustering of the processes. The new species is significantly larger than Q. pallida and is more square than rectangular. Q. pallida is not known to have a pylome.
Acritarch
De Verteuil and Norris, 1992 questionably included this species in Quadrina and regarded it as algae incertae sedis.
Holotype: De Verteuil and Norris, 1992, pl.6, fig.7
Locus typicus: St. Leonard Member ("Bed 18") of Choptank Fm, Scientists Cliffs, Chesapeake Bay, Calvert County, Maryland, U.S.A.
Stratum typicum: Late-middle Miocene
Original diagnosis: De Verteuil and Norris, 1992, p.420
Intermediate, pigmented, organic-walled microfossil with a rectangular, square or cruciform outline when compressed. The four corners or lobes each bear a cluster of approximately 8-20 hollow, tapered, and acuminate or capitate processes that are arranged in imperfect circular bands about the lobes. The processes are approximately 30-50% of vesicle diameter in length and appear to communicate with the internal cavity. All other areas are without processes. The wall appears autophragmal and is psilate to irregularly microgranulose. An excystment aperture is present but rarely discernable; it appears to be asymmetrically positioned with respect to the plane of bilateral symmetry passing between the process clusters, being partly within an area of process development.
Dimensions. As oriented in discussion: Apical/antapical height, 25(32)50 µm; holotype, 40 µm. Equatorial diameter, 25(33)52 µm; holotype, 42 µm. Processes, 8-23 µm; holotype, 10-13 µm. Fifteen specimens measured.
Affinities:
De Verteuil and Norris, 1992, p. 423: Quadrina? condita differs from Selenopemphix quanta and other spinate species of Selenopemphix in the clustering of the processes. The new species is significantly larger than Q. pallida and is more square than rectangular. Q. pallida is not known to have a pylome.