radiolaria - rads_cenozoic - Phormocyrtis striata praexquisita

Phormocyrtis striata praexquisita

Classification: rads_cenozoic -> Pterocorythidae -> Phormocyrtis -> Phormocyrtis striata -> Phormocyrtis striata praexquisita
Sister taxa: P. striata exquisita, P. striata praexquisita, P. striata striata


Citation: Phormocyrtis striata praexquisita Nishimura 1992
Rank: sub-species
Basionym: Phormocyrtis striata praexquisita
Taxonomic discussion: Nishimura 1992 Approved - Added on Leg 171 by Blome ; Paleogene RW_age: Lower part of Bekoma campechensis Zone.

Catalog entries: Phormocyrtis striata praexquisita

Original description: Cephalis subspherical, quite small, with very small pores all over, bearing a stout conical rod-like apical horn, three-bladed in the proximal part. Collar stricture with four collar pores internally, not defined externally. Cephalic structure has A, V, two L and D; V extends obliquely upward at quite a low angle, two l are incorporated into the stout septal ring. Two L and D are not connected to lateral ribs. Thorax subhemispherical, quite thick-walled, with subcircular pores with well-developed pore frames, slightly rough surface with nodal points. Abdomen inflated pyramidal, thick-walled, with subcircular, large pores, developing three convexly curved keels from the uppermost or median part of the abdomen, constricted aperture, termination ragged.

(Based on 10 specimens) Overall height 120-160 µ, height of cephalis and thorax 40-54 µ, maximum width of cephalis 24-32 µ, width of thorax 42-60 µ. Distinguishing characters (rw): This species seems to be closely related to Phormocyrtis striata exquisita. It is distinguished from the latter by the generally irregular structure of abdomen with outwardly curved keels and not regularly arranged longitudinal rows of pores.
Remarks on original description: Equivalent to Phormocyrtis striata exquisita (Kozlova) Westberg et al., 1980, pl.1, fig.13.




Biogeography and Palaeobiology

Similar species

Geographic distribution


Phylogenetic relations

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within Paleogene Period (23.03-66.04Ma, top in Chattian stage). Data source: Lazarus et al. 2015 - "P age group"
First occurrence (base): within Paleogene Period (23.03-66.04Ma, base in Danian stage). Data source: Lazarus et al. 2015 - "P age group"

Plot of occurrence data:


Nishimura, A. (1992). Paleocene radiolarian biostratigraphy in the northeast Atlantic at Site 384, Leg 43, of the Deep Sea Drilling Project. Micropaleontology. 38(4): 317-362. gs


Phormocyrtis striata praexquisita compiled by the radiolaria@mikrotax project team viewed: 29-11-2022

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