Original descriptions of taxa - also emended descriptions for a few taxa. For coccolithophores, and many calcispheres, these are pages from the Farinacci & Howe Catalog of Calcareous Nannofossils. In other cases (e.g. non-calcifying haptophytes) the data is directly compiled on this site. The "Catalogue of Calcareous Nannofossils" was originally compiled by Prof A. Farinacci 1969-1989, since 2000 it has been updated and extended by Richard Howe - see The Farinacci and Howe Catalog - an Introduction.
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Farinacci - Discoaster asymmetroivrachiones.pdf
Varol & Bowman 2024 pl33 f13-24.jpg
Varol & Bowman 2024 fig 9-05.JPG
Varol & Bowman 2024 fig 9-06.JPG
Current identification:
Compiled data
Citation: Discoaster asymmetroivrachiones Varol & Bowman 2024Taxonomic rank: speciesType specimens: Holotype: Plate 33, Figs. 13-24 (same specimen). Type age (chronostrat): Zone NN7, Middle Miocene. Type locality: IODP Leg 354, Hole 1451B, Ninetyeast Ridge, Bengal Fan, Indian Ocean, core 23R, section 1W, 104-105 cm. Type repository: Varol Research, LlandudnoRepository Country: Wales
Original Description An asymmetrical pentagonal species has segments with strongly tapering arms with simple terminations. The distinct proximal ridges without any knob decorate the proximal side, and sutural ridges created by the deep cavities are present on the distal side. Size: Dimensions of holotype: Maximum diameter: 7.88 µm, Diameter of the central area: 3.92 µm, Length of arms: 1.98 µm, Diameter of the proximal knob: 4.16 µm (measurements from bright field micrograph) Etymology: From the Greek asymmetroivrachiones, asymmetrical arms - refers to its asymmetrical arms. Extra details from original publication Remarks:Discoaster asymmetroivrachiones and Discoaster bengalica have pentagonal outlines. Discoaster asymmetroivrachiones have an asymmetrical outline with strongly tapering arms without bifurcations. Discoaster bengalica is a symmetrical species with tapering arms with bifurcated termination.
Occurrence: This species is recorded from IODP Leg 354, Hole 1451B, Ninetyeast Ridge, Bengal Fan, Indian Ocean and rarely various commercial oil wells in the Gulf of Mexico.
Varol, O. & Bowman, A. R. (2024). The new Middle Miocene genus Olladiscoaster, and related and associated discoasters. Grzybowski Foundation Special Publication. 28: 1-102. gs
Discoaster asymmetroivrachiones: Catalog entry compiled by Jeremy Young. Viewed: 6-9-2026