Ceratocyrtis histricosus, from

Belongs within: Nassellaria.
Contains: Theopiliinae, Neosciadiocapsinae, Lampromitrinae.

The Acropyramidoidea are a group of radiolarians known from the Triassic to the present (Afanasieva et al. 2005).

Characters (from Afanasieva et al. 2005): Two, less commonly one to four or more segments. Cephalis of various sizes. Three types of cephalis present: (1) spine A runs free as columella; cephalis not divided into lobes, being separating from thorax by basal arcs; (2) spine A near anterior wall; eucephalic and lateral lobes present; lateral lobes separated from thorax; arcs of basal ring not developed; (3) lobes and main spines of cephalis poorly developed; test mainly conical; external apophyses of spines D and L thin and poorly developed. Thorax forming largest part of external skeleton. In cases of cephalis of types 2 or 3 thorax occasionally having constrictions or transverse thickenings of wall, separating it into two or three, rarely more portions. Walls most often porous. Pores arranged in longitudinal or transverse rows. Finest meshwork with irregular arrangement of bars relatively rarely developed.

Acropyramidoidea [Stichoperilae, Triacartilae]AA05
    |    |--Quasipetasus Blome 1984AA05
    |    |--Pessagnocyrtium Kozur & Mostler 1981AA05
    |    `--Bulbocyrtium Kozur & Mostler 1981AA05
    |         `--B. reticulatumAA05
    |    |--Acropyramis Haeckel 1881AA05
    |    |--Bathropyramis Haeckel 1881AA05
    |    |--Cephalopyramis Haeckel 1881AA05
    |    |--Cinclopyramis Haeckel 1881AA05
    |    |--Cladachnidium Haeckel 1881AA05
    |    |--Enneapleuris Haeckel 1887AA05
    |    |--Haliphormatidium Campbell 1951AA05
    |    |--Litharachnidium Haeckel 1887AA05
    |    |--Peripyramis Haeckel 1881AA05
    |    |--Plectopyramis Haeckel 1881 (see below for synonymy)AA05
    |    |--Polypleuris Haeckel 1887AA05
    |    |--Sethopyramis Haeckel 1881AA05
    |    |--Spongopyramis Haeckel 1887AA05
    |    `--Litharachnium Haeckel 1860AA05
    |         `--L. tentorium Haeckel 1862BC98
    |--Sethophormididae [Sethophormida, Sethophormidae]AA05
    |    |--TheopiliinaeAA05
    |    |--NeosciadiocapsinaeAA05
    |    |--RotaforminaeAA05
    |    |    |--Rotaforma Pessagno 1970AA05
    |    |    `--Saturniforma Pessagno 1970AA05
    |    |--EnneaphormidinaeAA05
    |    |    |--Enneaphormis Haeckel 1881AA05
    |    |    |    `--E. rotulaAA05
    |    |    `--Protoscenium Jorgensen 1905AA05
    |    |         `--P. simplexAA05
    |    `--SethophormidinaeAA05
    |         |--Tetraphormis Haeckel 1881LT61
    |         |--Astrophormis Haeckel 1887AA05
    |         |--Sethophormis Haeckel 1881AA05
    |         |--Theophormis Haeckel 1881AA05
    |         |--Velicuculus Riedel & Campbell 1952AA05
    |         `--Retraphormis Haeckel 1882AA05
         |    |--Acidnomelos Foreman 1968AA05
         |    |--Botryopera Haeckel 1887AA05
         |    |--Cerataarachnium Haeckel 1881AA05
         |    |--Cornutanna Haeckel 1881AA05
         |    |--Cornutosa Haeckel 1881AA05
         |    |--Cornutura Haeckel 1881AA05
         |    |--Lithocampana Clark & Campbell 1942AA05
         |    |--‘Trisulcus’ Popofsky 1913 non Hitchcock 1865AA05
         |    `--Cornutella Ehrenberg 1838 [incl. Ceratarachnium Haeckel 1881, Orthocornutanna Clark & Campbell 1945]AA05
         |         |--*C. clathrata Ehrenberg 1838DZ03
         |         |--C. profunda Ehrenberg 1854BC98
         |         `--C. tella Dumitrica & Zügel 2003DZ03
              |--Antarctissa Petrushevskaya 1967AA05
              |--Bathrocalpis Clark & Campbell 1942AA05
              |--Gondwanaria Petrushevskaya 1975AA05
              |--Helotholus Jorgensen 1905AA05
              |--Periarachnium Haeckel 1881AA05
              |--Phlebarachnium Haeckel 1881AA05
              |--Pseudodictyophimus Petrushevskaya 1971AA05
              |    `--P. gracilipes (Bailey 1856)BC98
              `--Ceratocyrtis Buetschli 1882AA05
                   |--C. galleus (Cleve 1899)BC98
                   |--C. histricosus (Jørgensen 1905)BC98
                   `--C. hyperborea Jørgensen 1905BC98

Plectopyramis Haeckel 1881 [incl. Pyramis Campbell 1954 nec nec Röding 1798 nec Schumacher 1817 nec Colani 1924]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.

[BC98] Bjørklund, K. R., G. Cortese, N. Swanberg & H. J. Schrader. 1998. Radiolarian faunal provinces in surface sediments of the Greenland, Iceland and Norwegian (GIN) Seas. Marine Micropalaeontology 35: 105–140.

[DZ03] Dumitrica, P., & P. Zügel. 2003. Lower Tithonian mono- and dicyrtid Nassellaria (Radiolaria) from the Solnhofen area (southern Germany). Geodiversitas 25 (1): 5–72.

[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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