Discoaster diplasiastike
Set number: 3863
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10µm
Holotype in the mobile mount
Discoaster diplasiastike Varol & Bowman, 2024
Species have a large central area with sutural and distal ridges, deep cavities on the distal side, and a bulged proximal side with a platform created by ridges. The parallel-sided arms terminate in double bifurcation.
From the Greek diplasiastike, doubled - refers to double limbs of the bifurcation at the end of the segments.
Maximum diameter: 11.35 µm, Diameter of the central area: 6.36 µm, Length of the arms: 2.49 µm, maximum height: 5.82 µm (measurements from bright field micrograph).
The arms of the segments are much shorter than the diameter of the central area (about half). The segments terminate with bifurcation made by double limbs. The pre-terminal limbs are perpendicular to the length of the segments, but the terminal limbs make an obtuse angle with the length of the segments. The angle between the terminal limbs is acute (about 50-70º). The inner arm area is half-moon in shape.
The distal side is ornamented with prominent sutural ridges, deep cavities and distal ridges. The ridges create a proximal platform to decorate the bulged proximal side.
Discoaster diplasiastike differs from double-limbed bifurcated Discoaster emblematicus, Discoaster saundersii and Discoaster durioi by having a proximally bulged central area with proximal ridges and a platform and distal ridges. It is further distinguished from Discoaster saundersii by having sutural ridges and cavities on the distal side. Discoaster diplasiastike is differentiated from Discoaster mendomobensis by having double-limbed bifurcation and a proximally bulged central area with proximal ridges and a platform and distal ridges.
Varol, O. & Bowman, A. R. 2024. The New Middle Miocene Genus Olladiscoaster, and Related and Associated Discoasters. Grzybowski Foundation Special Publication, 28: 1-103 pp.
Holotype
Discoaster diplasiastike
Varol & Bowman, 2024
Middle Miocene
USGS-NASA Langley Core, Hampton, VA (USA)