Stichopilium bicorne, from Haeckel (1887).

Belongs within: Acropyramidoidea.

The Theopiliinae are a group of conical, flattened radiolarians known from the Triassic to the present (Afanasieva et al. 2005).

Characters (from Afanasieva et al. 2005): Two or three (or more, up to eight) segments, conical, flattened. Collar strictum indistinct. Arcs of basal ring developed. Cephalis of type 2. In walls of thorax shelves and constrictions, its upper part may be separated by constriction with pedestal. Skirt extending sideways with one to six concentric rows of pores present or cylindrical orally narrowed terminal segment may be present. Aperture terminal, closed by velum, stretched on shelf, or open. Velum flat or bowl-shaped; penetrated or not penetrated by pores. Wall porous. Pores arranged in transverse concentric rows. Third segment (or skirt) sometimes with longitudinal and transverse rows of pores. Sometimes subsidiary spongy layer developed externally. Spine A externally developing significant apical horn. Short tube-cephalopyle or horn (almost similar to that as apical) connected to spine V. Spines D and L extending as costae in second part of second segment. Their ends sticking free in shape of faceted lateral apophyses of test, but not forming significant feet.

<==Theopiliinae (see below for synonymy)AA05
    |--Clathrocyclas Haeckel 1881AA05
    |--Clathrocycloma Haeckel 1887AA05
    |--Diplocyclas Haeckel 1881AA05
    |--Eucecryphalus Haeckel 1860AA05
    |--Haeckelicyrtidium Kozur & Mostler 1979AA05
    |--Phrenocodon Haeckel 1887AA05
    |--Pterocorythium Haeckel 1887AA05
    |--Salpingocapsa Ruest 1885AA05
    |--Squinabolella Pessagno 1969AA05
    |--Theocalyptra Haeckel 1881AA05
    |--Theopilium Haeckel 1881AA05
    |--Podocampe Haeckel 1881 (n. o.)AA05
    |--Stichocyrtis Haeckel 1881 (n. o.)AA05
    |--Stichopera Haeckel 1881AA05
    |--Cecryphalium Haeckel 1881AA05
    |    `--C. sestrodiscusAA05
    |--Anthocyrtella Haeckel 1881AA05 [=Anthocyrtis Ehrenberg 1847 non Ehrenberg 1846LT61; Anthocyrtida]
    |    |--*A. (Anthocyrtella) mespilus (Ehrenberg 1854) [=*Anthocyrtis mespilus]LT61
    |    `--A. (Anthocyrtura Haeckel 1887)LT61
    `--Stichopilium Haeckel 1881AA05 [=Triacartus Haeckel 1881LT61]
         |--*S. bicorne [=*Triacartus bicornis]LT61
         `--S. cortina Haeckel 1887 [=Triacartus cortina]LT61

Theopiliinae [Podocampida, Stichocyrtdia, Stichoperida, Stichoperidae, Stichoperinae, Stichopilida, Stichopiliidae, Tetracyrtida, Theopiliidae, Triacartidae, Triacartinae]AA05

*Type species of generic name indicated


[AA05] Afanasieva, M. S., E. O. Amon, Y. V. Agarkov & D. S. Boltovskoy. 2005. Radiolarians in the geological record. Paleontological Journal 39 (Suppl. 3): S135–S392.

[LT61] Loeblich, A. R., Jr & H. Tappan. 1961. Remarks on the systematics of the Sarkodina (Protozoa), renamed homonyms and new and validated genera. Proceedings of the Biological Society of Washington 74: 213–234.

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