PHACODISCIDAE 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 : 424

Family PHACODISCIDAE Haeckel, 1882

Phacodiscida Haeckel, 1882: 456 [as a subfamily]; 1887: 409, 419-421 [as a family]. — Bütschli 1889: 1958 [as a family]. — nec Rüst 1892: 165 [as a family]. — Schröder 1909: 3 [as a family]. — Anderson 1983: 24 [as a family].

Phacodisciden – Haecker 1907: 123.

Phacodiscidae – Haecker 1908: 444. — Popofsky 1912: 126. — Clark & Campbell 1942: 38; 1945: 20. — Campbell & Clark 1944b: 14. — Campbell 1954: D78. — Orlev 1959: 443. — Chediya 1959: 124. — Riedel 1967b: 294; 1971: 653. — Nigrini 1974: 1065. — Nakaseko et al. 1975: 169. — Nakaseko & Sugano 1976: 125. — Tan & Tchang 1976: 241. — Riedel & Sanfilippo 1977: 864. — Dumitrica 1979: 21. — Kozur & Mostler 1979: 35 ( sensu emend. ). — Tan & Su 1982: 151. — Anderson 1983: 38. — Takahashi 1991: 89. — Chen & Tan 1996: 151. — Hollis 1997: 40. — Boltovskoy 1998: 31. — Tan 1998: 203. — Tan & Chen 1999: 204. — Anderson et al. 2002: 1002.

Phacodiscinae – Campbell 1954: D78. — Petrushevskaya & Kozlova 1972: 522. — Dumitrica 1984: 96-97.

TYPE GENUS. — Phacodiscus Haeckel, 1882: 457 [type species by subsequent designation ( Campbell 1954: D78): Phacodiscus rotula Haeckel, 1887: 424 ].

INCLUDED GENERA. — Periphaena Ehrenberg, 1874: 246 (= Astrophacomma , Heliodiscomma synonymized by Sanfilippo & Riedel 1973: 522; Perizona synonymized by Kozur & Mostler 1972: 19). — Phacodiscus Haeckel, 1882: 457 (= Phacodiscinus with the same type species; Astrophacilla n. syn., Paracenodiscus n. syn., Phacodisculus n. syn., Prunulum n. syn., Prunuletta n. syn., Sethodiscinus n. syn.).

INVALID NAME. — Coccymelium .

NOMINA DUBIA. — Conophacodiscus, Pentadiscus, Triadiscus.

DIAGNOSIS. — Shell roughly flat, consists of a large convex lensshaped latticed shell. Radial beams arise from the outer medullary shell and radiate to both sides of the equatorial plane. These beams are connected to the large latticed shell. Exterior structure outside of the large latticed shell absent or exclusively represented by a simple solid flat circular edge which is surrounded by distinctive solid arrowhead-like short spines. No structure extends to both sides of the equatorial plane.

STRATIGRAPHIC OCCURRENCE. — Early Eocene-Living.

REMARKS

Phacodiscus shares a homeomorphous appearance to Heliodiscus representatives without spines. The latter genus is a living form and has a characteristic microsphere, always eccentrically placed in the second inner shell (outer double medullary shell). The Phacodiscidae are an extinct family, whereas Heliodiscidae is a common component of living plankton. Periphaena has a special distinguishable pore near its center on one side of the cortical shell, probably an exit for the axoflagellum ( Sugiyama & Furutani 1992: pl. 16, fig. 6). The internal skeletal structure of Periphaena has been illustrated ( Sugiyama & Furutani 1992: pl. 16, fig. 5).

VALIDITY OF GENERA

Phacodiscus

The same type species was designated for the following combinations of genera: Phacodiscus and Phacodiscinus ; and Prunulum , Prunuletta and Coccymelium . Haeckel (1887) seems to propose new taxon name for differently oriented specimens in some cases. Sethodiscinus is considered to have a simple medullary shell ( Campbell 1954: D78), but the innermost shell is known to be easily dissolved. Phacodiscus is validated due to the oldest available name among them. The type image for Phacodiscus is poor ( Haeckel 1887: pl. 35, fig. 7) but it is unfortunately “ Phacodiscus ” can be precisely identified by using this poor image.