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Muderongia aequicornus
Muderongia aequicornus Arhus in Arhus et al., 1990; emend. Monteil, 1991
Holotype: Arhus et al., 1990, fig.12H
Age: Early Barremian
Original description (Arnhus, 1990):
Muderongia aequicornus sp. nov. Fig. llJ, Fig. 12B, G, H (holotype)
Derivation of name. - With reference to the equal lengths of the right and left lateral horn and also to the two equal antapical horns.
Material. - Borehole 7320/3-U-1 at 27.440 m. A few specimens recorded per slide from seven samples, but more commonly in one sample from the top of the core.
Description. - Proximate cyst, cornucavate. Endophragm rounded, more or less protruding into the five horns. The apical and two straight antapical diverging horns are about 50 µm long and gently tapering throughout their length. Stout, blunt lateral horns, in the order of 15 µm long with paracingular notches. Operculum usually detached. Paraplates not discernible.
Remarks. - In spite of the often difficult distinction of species within this genus, the morphology of this species shows little variation in core 7320/3-U-l. Muderongia testudinaria Burger 1980 and Muderongia asymmetrica Brideaux 1977 are the most similar species, but both have relatively long postcingular extensions of their cingular horns. The antapical horns of M. asymmetrica are of unequal length.
Stratigraphic range. -Known only from the Lower Barremian.
Holotype: Arhus et al., 1990, fig.12H
Age: Early Barremian
Original description (Arnhus, 1990):
Muderongia aequicornus sp. nov. Fig. llJ, Fig. 12B, G, H (holotype)
Derivation of name. - With reference to the equal lengths of the right and left lateral horn and also to the two equal antapical horns.
Material. - Borehole 7320/3-U-1 at 27.440 m. A few specimens recorded per slide from seven samples, but more commonly in one sample from the top of the core.
Description. - Proximate cyst, cornucavate. Endophragm rounded, more or less protruding into the five horns. The apical and two straight antapical diverging horns are about 50 µm long and gently tapering throughout their length. Stout, blunt lateral horns, in the order of 15 µm long with paracingular notches. Operculum usually detached. Paraplates not discernible.
Remarks. - In spite of the often difficult distinction of species within this genus, the morphology of this species shows little variation in core 7320/3-U-l. Muderongia testudinaria Burger 1980 and Muderongia asymmetrica Brideaux 1977 are the most similar species, but both have relatively long postcingular extensions of their cingular horns. The antapical horns of M. asymmetrica are of unequal length.
Stratigraphic range. -Known only from the Lower Barremian.