radiolaria - rads_cenozoic - Joergensenium arcticum radiolaria - rads_cenozoic - Joergensenium arcticum

Joergensenium arcticum

Classification: rads_cenozoic -> Actinommidae -> Quinquecapsulariidae -> Joergensenium -> Joergensenium arcticum
Sister taxa: J. arcticum, J. clevei, J. rotatile, J. sp.


Citation: Joergensenium arcticum Ikenoue et al. 2016
taxonomic rank: species
Basionym: Joergensenium arcticum Ikenoue et al. 2016
2003 Actinomma leptoderma leptoderma - Itaki et al. Plate 1, Fig. 12
2015 Joergensenium sp. A - Ikenoue et al. Plate 4, figs. 1-5
2016 Joergensenium arcticum - Ikenoue et al. Text-Fig. 2.2; Plates 1-6

Catalog entries: Joergensenium arcticum

Original description: Description: Shell spherical consisting of one simple or double cortical shell and one double medullary shell consisting of microsphere and second medullary shell. Microsphere looks like a pentagonal prism the corners of which bear one ray. One lateral edge is straight, the other four are curved and bear also a ray in their middle, so that the total number of rays originated in the microsphere is 14. All microspheric rays stop in the wall of the second medullary shell (partly seen on Plate 2, Figs. 1c, 2a, 3c; Plate 6, Figs. 2b c) and are interconnected by arches that form in its wall with slightly marked constrictions and slightly marked cupolas. Second medullary shell thin-walled with rounded pores of irregular size and arrangement. Their cupolas bear one to two three-bladed radial bars prolonged outside the cortical shell into about 10-15 relatively long pointed spines. Cortical shell is spherical and may be single (Plate 2, Figs. 4-8; Plate 5, Fig. 1; Plate 6, Fig. 1) or double (Plate 3, Figs. 1-7; Plate 4, Figs. 1-2; Plate 5, Figs. 2-3). When single, it is thin walled and has rounded pores of various shapes, sizes and arrangement (Plate 2, Fig. 7a; Plate 5, Fig. 1). When double, the external one is close to the internal shell, spongy-like, fibrillar, formed of thin threads uniting very irregularly the ends of numerous by-spines arising from the wall of the inner cortical shell (Plate 3, Figs. 3, 5-6; Plate 5, Figs. 2-3).


Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): Extant. Data source:
First occurrence (base): within Recent modern (0.00-0.00Ma, base in "Holocene" stage). Data source:

Plot of occurrence data:


Ikenoue, T., Bjorklund, K. R., Kruglikova, S. B., Onodera, J., Kimoto, K. & Harada, N. (2015). Flux variations and vertical distributions of siliceous Rhizaria (Radiolaria and Phaeodaria) in the western Arctic Ocean: indices of environmental changes. Biogeosciences. 12(6): 2019-2046. gs

Ikenoue, T., Bjørklund, K. R., Dumitrica, P., Krabberoed, A. K. & Kimoto, K. (2016). Two new living Entactinaria (Radiolaria) species from the Arctic province: Joergensenium arcticum n. sp. and Joergensium clevei n. sp. Marine Micropaleontology. 124: 75-94. gs

Itaki, T., Ito, M., Narita, H., Ahagon, N. & Sakai, H. (2003a). Depth distribution of radiolarians from the Chukchi and Beaufort Seas, western Arctic. Deep-Sea Research Part I: Oceanographic Research Papers. 50(12): 1507-1522. gs


Joergensenium arcticum compiled by the radiolaria@mikrotax project team viewed: 3-3-2024

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