radiolaria - rads_cenozoic - Phormocyrtis ligulata radiolaria - rads_cenozoic - Phormocyrtis ligulata

Phormocyrtis ligulata

Classification: rads_cenozoic -> Pterocorythidae -> Phormocyrtis -> Phormocyrtis ligulata
Sister taxa: P. alexandrae, P. cubensis, P. embolum, P. ligulata, P. proxima, P. striata, P. turgida, P. sp.


Citation: Phormocyrtis ligulata Clark & Campbell 1942
taxonomic rank: species

Catalog entries: Phormocyrtis ligulata

Original description: Shell smooth, with maximum breadth high up on thorax, the shell as a whole generally spindle-shaped, with strong surface ribs; apical horn usually relatively short (never exceeding 0.26 and sometimes only 0.1 total length), conical in outline (not exceeding 5° except in exceptional individuals), equally bladed, with four fins, tip usually sharp, basally fused to the top of the cephalis, sometimes asymmetrical although typically vertical; cephalis conical (often about 45°, exceptionally as much as 70°), the top rounded off and merged with the base of the horn, the base distinguished by change in contour at its junction with thorax, its length hardly more than 0.1 total length, and its basal diameter perhaps 1.5 times as much as the height, its sides sometimes convex and more or less rarely asymmetrical; thorax with strongly rounded shoulder reaching a maximum diameter of 0.43 total length near 0.5 total length (being approximately 45°); below this wide level the thorax rapidly contracts (48°) to the lower margin with regularly decreasing diameter, the breadth at the lowest level, commonly about 0.4 total length (sometimes more as in Fig. 22), the lowest level of thorax marked by an internal, horizontal, narrowed, septal band; abdomen continued in contour with the thorax (48°) and squarely truncated (except, of course as torn or injured) around the aperture whose diameter is most usually about 0.24 total length; wall uniform, trim; surface of cephalis, with vertical rows of four to six small, circular pores and with strong, apically decurrent, vertical, convergent, creases or ribs separating the rows, these ribs continued basally with those of the thorax; of thorax, with a dozen to fifteen vertical rows of six or eight, round, not very large, well-spaced pores, between the rows; the ribs of the cephalis are continued in similar number as even stronger and higher creaselike ribs; of abdomen, with the same number of rows of pores, these pores about three or four in a vertical row, larger and much more irregular (or even rectangular) than those of the thorax; sometimes they are more or less fused and run together in twos and threes, otherwise the framework glassy, and the ribs die away gradually above the middle of the abdomen having been continued that far from the thorax; aperture simple, its margin often torn and ragged.


Biogeography and Palaeobiology

Biostratigraphic distribution

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

Plot of occurrence data:



Phormocyrtis ligulata compiled by the radiolaria@mikrotax project team viewed: 21-7-2024

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