Belongs within: Cidaroida.
The Goniocidarinae are a group of more or less flattened sea urchins known from the Eocene to the present (Fell 1966).
Characters (Fell 1966): Test usually flattened above and below. Grooves or pits, or both, on horizontal sutures of interambulacra and ambulacra, commonly confluent with median vertical grooves. Primary tubercles adorally noncrenulate, aborally noncrenulate or weakly subcrenulate. Pores nonconjugate, close together. Tridentate pedicellariae unknown. Globiferous pedicellariae present, small forms with end tooth, large forms without it.
<==Goniocidarinae [Goniocidarina]F66
|--Psilocidaris Mortensen 1927F66
| `--*P. echinulata Mortensen 1927F66
|--Schizocidaris Mortensen 1903F66
| `--*S. assimilis Mortensen 1903F66
|--Rhopalocidaris Mortensen 1927F66
| |--*R. hirsutispina (de Meijere 1904) [=Cidaris hirsutispinus]F66
| `--R. gracilis Döderlein 1885MG-H11
`--Goniocidaris Desor in Agassiz & Desor 1846 [=Adelcidaris Cotton & Godfrey 1942; incl. Stephanocidaris Agassiz 1863]F66
|--G. (Goniocidaris)F66
| |--*G. (G.) tubaria (Lamarck 1816) [=Cidarites tubaria, *Adelcidaris tubaria]F66
| |--G. (G.) hebeF66
| |--G. (G.) pusillaF66
| `--G. (G.) umbraculumF66
|--G. (Aspidocidaris Mortensen 1928)F66
| |--G. (*A.) alba (Mortensen 1928) [=*Aspidocidaris alba]F66
| `--G. (A.) parasolF66
|--G. (Cyrtocidaris Mortensen 1927)F66
| `--G. (*C.) tenuispina Mortensen 1927F66
|--G. (Discocidaris Döderlein 1885)F66
| `--G. (*D.) mikado Döderlein 1885F66
`--G. (Petalocidaris Mortensen 1903)F66
`--G. (*P.) florigera Agassiz 1879F66
*Type species of generic name indicated
References
[F66] Fell, H. B. 1966. Cidaroids. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt U. Echinodermata 3 vol. 1 pp. U312–U339. The Geological Society of America, Inc., and The University of Kansas Press.
[MG-H11] McEnnulty, F. R., K. L. Gowlett-Holmes, A. Williams, F. Althaus, J. Fromont, G. C. B. Poore, T. D. O’Hara, L. Marsh, P. Kott, S. Slack-Smith, P. Alderslade & M. V. Kitahara. 2011. The deepwater megabenthic invertebrates on the western continental margin of Australia (100–1100 m depths): composition, distribution and novelty. Records of the Western Australian Museum Supplement 80: 1–191.