Lithocyclia

Cannartus tubarius, from here.

Belongs within: Corticata.

The Lithocyclia lineage of radiolarians originated in the middle Eocene with discoidal forms (Lithocyclia) that later evoleved into ellipsoidal forms (Cannartus and Ommatartus).

Characters (from Sanfilippo & Riedel 1980, as Coccodiscidae): Discoidal forms consisting of a lenticular cortical shell enclosing a small single or double medullary shell, and surrounded by an equatorial zone of spongy or concentrically-chambered structure, OR forms with ellipsoidal cortical shell, usually equatorially constricted and enclosing a single or double medullary shell, the opposite poles of the shell generally bearing spongy columns and/or single or multiple latticed caps.

Lithocyclia
    |--L. ocellus P98
    `--+--L. aristotelis P98
       `--+--L. angusta P98
          `--Cannartus P98
               |--C. tubarius P98
               `--+--C. violina P98
                  `--+--C. mammiferus P98
                     `--+--C. laticonus P98
                        |--+--‘Ommatartus’ hughesi P98
                        |  `--C. petterssoni P98
                        `--Ommatartus P98
                             |--O. antepenultimus P98
                             `--+--O. penultimus P98
                                `--+--O. avitus P98
                                   `--O. tetrathalamus P98

*Type species of generic name indicated

REFERENCES

[P98] Prothero, D. R. 1998. Bringing Fossils to Life: An introduction to paleobiology. WCB McGraw-Hill: Boston.

Sanfilippo, A., & W. Riedel. 1980. A revised generic and suprageneric classification of the artiscins (Radiolaria). Journal of Paleontology 54 (5): 1008-1011.