Polycystinea - Nassellaria - Hilarisiregidae
Original description: Cephalis large, hemispherical, imperforate, covered with layer of microgranular silica. Two horns widely displaced, thin to medium in thickness, short, triradiate in axial section with three narrow grooves alternating with three medium width ridges. Thorax large, ellipsoidal to subhemispherical in outline. Mesh work of thorax double-layered with small triangular or tetragonal pore frames superimposed by large circular pore frames. Four feet relatively massive, elongate, originating from upper portion of thorax. Feet triradiate in axial section with three narrow ridges alternating with three wide grooves. Aperture large, subcircular in outline.
Original remarks: Rolumbus hilarus, n. sp., can be distinguished from other Rolumbus spp. in this report by having a thorax with a double-layered test wall, and by having short horns which are widely displaced.
Etymology: Hilarus-a-um (Latin, adj.) cheerful.
Full reference: K. Y. Yeh. 1987. Taxonomic Studies of Lower Jurassic Radiolaria from East-Central Oregon. National Museum of Natural Science Special Publications 2:1-169
Belongs to Rolumbus according to K. Y. Yeh 1987
Sister taxa: Diceratigalea gastili, Diceratigalea halseyensis, Rolumbus lautus, Rolumbus beatus
Type specimen: NMNS (000117). Its type locality is Suplee-Izee area, OR-589D, which is in a Toarcian marine mudstone/limestone in the Snowshoe Formation of Oregon.
Distribution:
• Jurassic of United States (3: Oregon collections)
Total: 3 collections each including a single occurrence
Specimen images are retrieved through the ePANDDA API.
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