Catalog entries: Orbula ducalis
Original description: Cephalis subspherical in lateral view, subtriangular in transverse section, with corners of triangle truncate coinciding with position of vertical and secondary lateral bars which protrude as tiny thorns. Apical horn may be small, thorn-like, or larger and cylindrical. Cephalis and proximal thorax poreless, minutely papillate. Cephalis pitted apically, distally frequently nodose. Internally the collar stricture has six collar pores as in 0. comitata. Externally the collar stricture not distinct as the contour of the cephalis merges with that of the thorax. Thorax with two distinct flaring expansions, the distalmost much broader than the first; subtriangular in transverse section. Aperture constricted, subtriangular, surrounded by a rounded rim with surface minutely papillate. Three ribs extend from the collar stricture and terminate in three short feet at the point where the thorax constricts. Thoracic pores subcircular, arranged quincuncially in vertical rows, gradually increasing in size to the point of greatest expansion; surface tuberculate.
(Based on twenty specimens) Length of cephalis and thorax 100-150µm; greatest width of thorax 190-245µm, of aperture 120-160µm. Distinguishing characters (rw): This species is distinguished from 0. comitata and 0. discipulus as described under those species.
Last occurrence (top): within Paleogene Period (23.03-66.04Ma, top in Chattian stage). Data source: Lazarus et al. 2015 - "P age group"
First occurrence (base): within Paleogene Period (23.03-66.04Ma, base in Danian stage). Data source: Lazarus et al. 2015 - "P age group"
Plot of occurrence data:
Orbula ducalis compiled by the radiolaria@mikrotax project team viewed: 19-9-2020
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