Helotholus


Classification: rads_cenozoic -> hidden -> deleted -> Helotholus
Sister taxa: A. leptoderma, A. undulatum, Clathrocorona, Clathromitridae, Euscenarium, Helotholus, Lamprocylcas, L. parabolica, Pyloniidae inc sed, R. oraculibrachium, S. sp. cf. elliptica, T. tricostatum, Tripophaenoscenium, Unknown, Myelastridae, Archiphormididae, Cenozoic uncertain, H. sp., T. sp., T. sp.

Taxonomy

Citation: Helotholus Jørgensen 1905
Rank: genus
Basionym: Helotholus

Catalog entries: Helotholus

Original description: The four primary spines with the ventral, sagittal one. All five protrude as single spikes, the dorsal one, A, down on the thorax, the ventral, sagittal one in the neck stricture, the one marked D, on the cephalis as an apical spine. The lower part of this latter spine is inside the wall of the cephalis, while it a little higher up runs in the very wall. It is therefore no genuine columella. There;is also an axial spine, as in the other species here mentioned of the Cyrtoidea group. This axial spine starts as usual from the ventral end of the central rod, in the interior of the lattice shell, a little below the neck stricture, and is in elder individuals of Helotholus histricosa divided in two.

The thorax is broadly campanulate, nearly semispherical.
Remarks on original description: [Synonymized with Ceratocyrtis Bütschli by Petrushevskaya, 1971b]

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): at top of Piacenzian Stage (100% up, 2.6Ma, in Piacenzian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Danian Stage (0% up, 66Ma, in Danian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Jørgensen, E (1905). The protist plankton and diatoms in bottom samples: Radiolaria. In, Nordgaard (ed.) Hydrographical and biological investigation in Norwegian Fjord. 49-151. gs

Missing or ambiguous references: ; ;


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Helotholus compiled by the radiolaria@mikrotax project team viewed: 11-4-2021

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