STEPHANIIDAE Haeckel, 1882

Suzuki, Noritoshi, Caulet, Jean-Pierre & Dumitrica, Paulian, 2021, A new integrated morpho- and molecular systematic classification of Cenozoic radiolarians (Class Polycystinea) - suprageneric taxonomy and logical nomenclatorial acts, Geodiversitas 43 (15), pp. 405-573 : 494

Family STEPHANIIDAE Haeckel, 1882

Stephanida Haeckel, 1882: 444 [as a family]; 1887: 937-940 [as a family]. — Lankester 1885: 849 [as a family]. — Bütschli 1889: 1976 [as a family]. — nec Rüst 1892: 176. — Anderson 1983: 29 [as a family].

Stephida – Lankester 1885: 850 [as a family].

Cortinida Haeckel, 1887: 940, 950 [as a subfamily].

Stephaniidae – Poche 1913: 219. — Campbell 1954: D106. — Petrushevskaya 1981: 371; 1986: 132. — Afanasieva et al. 2005: S305. — Afanasieva & Amon 2006: 155.

Stephanidae [sic] – Popofsky 1913: 283-284 (= Stephaniidae ). — Schröder 1914: 87. — Chediya 1959: 167. — Tan & Tchang 1976: 269. — Cachon & Cachon 1985: 291-292. — Chen & Tan 1996: 152. — Tan & Chen 1999: 270. — Tan & Su 2003: 83. — Chen et al. 2017: 165.

Stephaniinae – Campbell 1954: D106.

Cortiniae – Chediya 1959: 169.

TYPE GENUS. — Stephanium Haeckel, 1887: 952 [type species by subsequent designation ( Campbell 1954: D106): Stephanium quadrupes Haeckel, 1887: 952 ] = junior subjective synonym of Zygocircus Bütschli, 1882: 496 [type species by monotypy: Lithocircus productus Hertwig, 1879: 197 ].

INCLUDED GENUS. — Zygocircus Bütschli, 1882: 496 (= Cortina n. syn., Plagiocarpa n. syn., Stephanium n. syn.).

DIAGNOSIS. — The skeleton consists of only a sagittal ring. The Lo-axis is parallel to the Pl-axis while the Md-axis is parallel to Sg-axis. The endoplasm is spherical and located in the area encircled by the sagittal ring. Algal symbionts may or may not be present. Even if present, algal symbionts are uncommon and densely distributed around the endoplasm within the area of the sagittal ring.

STRATIGRAPHIC OCCURRENCE. — early Middle Eocene-Living.

REMARKS

In the case of very young Acanthodesmioidea , it is nearly impossible to differentiate them from the true Zygocircus . “Living” and protoplasm images were illustrated for Zygocircus ( Cachon & Cachon 1985: fig. 53.a; Matsuoka 1993a: fig. 2.3; Suzuki et al. 2009b: figs 3I, 3J; Suzuki & Not 2015: fig. 8.11.3; Matsuoka et al. 2017: Appendix B). The Stephaniidae have been overlooked due to their small size and their transparent protoplasm observed in plankton studies. Zygocircus has simply been identified as Zygocircus productus Hertwig 1879 , even if real specimens may be completely different from the type-illustration in Hertwig (1879). However, this should be avoided as algal symbiont-bearing Zygocircus possesses a different morphology to that of the Zygocircus without algal symbionts.

VALIDITY OF GENERA

Zygocircus

The Zygocircus -form includes not only fully-grown forms but also very young stages of Acanthodesmioidea , being unable to clearly differentiate them. For a simply practical identification, Zygocircus includes here into a single genus the morphotypes with a complete or incomplete D-ring, three or more basal feet directly extending from the initial spicular system and no arches except for the D-ring. Zygocircus was published by Bütschli (1882: 496), the same year as Plagiocarpa by Haeckel (1882: 424). Zygocircus is selected as the valid genus because its type species was illustrated only in 1882.