LITHOCYCLIIDAE Ehrenberg, 1846

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 : 420-422

Family LITHOCYCLIIDAE Ehrenberg, 1846

Lithocyclidina Ehrenberg, 1846: 385 [as a family]; 1847: 54 [as a family]; 1876: 156. — Schomburgk 1847: 124, 126 [as a family].

Coccodiscida Haeckel, 1862: 240, 485 [as a tribe]; 1882: 458 [as a subfamily]; 1887: 409, 455-458 [as a family]. — Zittel 1876-1880: 124 [rank unknown]. — Mivart 1878: 176 [as subsection]. — Bütschli 1889: 1959 [as a family]. — nec Rüst 1892: 166 [as a family]. — Anderson 1983: 24 [as a family].

Lithocyclida – Haeckel 1882: 458 [as a tribe]; 1887: 458, 459 [as a subfamily].

Staurocyclida Haeckel, 1882: 458 [as a tribe].

Trochodiscida Haeckel, 1887: 411, 412 [nomen dubium, as a subfamily]. — Schröder 1909: 39 [as a subfamily].

Heliosestrida Haeckel, 1887: 421, 427 [as a subfamily]. — Schröder 1909: 41 [as a subfamily].

Coccodiscidae – Poche 1913: 209. — Campbell & Clark 1944b: 14. — Campbell 1954: D82. — Chediya 1959: 128. — Riedel 1967b: 294; 1971: 653-654. — Riedel & Sanfilippo 1971: 1588; 1977: 865. — Kozur & Mostler 1972: 45. — Petrushevskaya & Kozlova 1972: 522. — Nakaseko et al. 1975: 169. — Nakaseko & Sugano 1976: 125. — Dumitrica 1979: 21-22; 1984: 96. — Sanfilippo & Riedel 1980: 1009 ( sensu emend. ). — Anderson 1983: 38-39. — Sanfilippo et al. 1985: 653. — Blueford 1988: 248. — Takahashi 1991: 79. — van de Paverd 1995: 137. — Boltovskoy 1998: 31. — Anderson et al. 2002: 1002. — De Wever et al. 2001: 121. — Afanasieva et al. 2005: S288. — Afanasieva & Amon 2006: 131. — Chen et al. 2017: 137-138.

Lithocyclinae – Campbell & Clark 1944b: 14. — Chediya, 1959: 128.

Heliosestrinae – Campbell & Clark 1944b: 14. — Clark & Campbell 1945: 20. — Campbell 1954: D78. — Chediya 1959: 125.

Trochodiscinae – Campbell 1954: D77 [nomen dubium]. — Chediya 1959: 122.

Coccodiscinae – Campbell 1954: D82. — Kozur & Mostler 1972: 45-46. — Petrushevskaya & Kozlova 1972: 523. — Sanfilippo & Riedel 1980: 1009. — Dumitrica 1984: 97. — Sanfilippo et al. 1985: 653. — De Wever et al. 2001: 121. — Afanasieva et al. 2005: S288. — Afanasieva & Amon 2006: 131.

Lithocycliidae – Petrushevskaya 1986: 128. — Kozlova 1999: 83.

TYPE GENUS. — Lithocyclia Ehrenberg, 1846: 385 [type species by subsequent monotypy: Astromma aristotelis Ehrenberg, 1847: 55 ].

INCLUDED GENERA. — Cromyatractus Haeckel, 1887: 334 (= Cromyatractium with the same type species; Caryatractus n. syn.). — Heliosestrum Haeckel, 1882: 457 (= Heliosestantha with the same type species; Astrosestrum synonymized by Kozur & Mostler 1972: 19; Astrosestantha n. syn., Astrophacura n. syn.). — Heliostylus Haeckel, 1882: 457 (= Astrostylus synonymized by Kozur & Mostler 1972: 19; Stylodiscus synonymized by Sanfilippo & Riedel 1973: 522, Stylentodiscus n. syn.). — Lithocyclia Ehrenberg, 1846: 385 (= Astrocyclia synonymized by Riedel & Sanfilippo 1970: 522; Coccodiscus synonymized by Kozur & Mostler 1972: 46). — Phacostaurus Haeckel, 1882: 457 (= Phacostaurium with the same type species; Astrostaurus synonymized with Kozur & Mostler 1972: 19; Crucidiscus n. syn., Heliostaurus n. syn., Sethostaurium n. syn., Sethostaurus n. syn., Staurentodiscus n. syn.). — Phacotriactis Sutton, 1896: 61 . — Sethostylus Haeckel 1882: 457 (= Sethostylium with the same type species; Amphicyclia synonymized by Petrushevskaya & Kozlova 1972: 522; Phacostylus n. syn., Phacostylium n. syn.). — Staurocyclia Haeckel, 1882: 458 (= Coccostaurus synonymized by Campbell 1954: D82). — Triactiscus Haeckel, 1882: 457 (= Trigonocyclia n. syn.).

NOMINA DUBIA. — Coccocyclia , Echinactura , Heliosestomma , Pristodiscus , Stauractinium , Stauractura , Stauracturium , Staurexodiscus , Stylexodiscus , Theodiscoma , Theodiscura , Theodiscus , Trochodisculus , Trochodiscus .

JUNIOR HOMONYM. — Staurodiscus Krasheninnikov, 1960 (= Heliosestrum ) nec Haeckel, 1879.

DIAGNOSIS. — Shell roughly flat, consisting of a large convex lensshaped latticed shell. Radial beams arise from the outer medullary shell and radiate to both sides of the equatorial plane. They are connected to the large latticed shell. No three-dimensional gridlike arms are observed. One of the following exterior structures is present outside of the large latticed shell: - a wide ring made of a grid-like structure (e.g., Cromyatractus , Lithocyclia , Staurocyclia ); - a solid flat circular edge surrounded by many solid arrowhead-like short spines (e.g., Heliosestrum ); - and/or two to four solid spines distributed under two-fold, threefold or four-fold symmetries (e.g., Cromyatractus , Heliostylus, Phacostaurus , Phacotriactis , Staurocyclia, Triactiscus ). Radial spines, if present, are not connected with the double medullary shell; or connected to the double medullary shell (e.g., Amphicyclia, Cromyatractus and Heliostylus ). No significant structures develop on each of the two sides of the equatorial plane.

STRATIGRAPHIC OCCURRENCE. — Late Paleocene-Living.

REMARKS

This family used to be named Coccodiscidae . However, the oldest senior synonym is Lithocycliidae Ehrenberg 1846 , and not Coccodiscidae Haeckel 1862 . Lithocycliidae was used as a valid family (see synonymy above); the valid family name must therefore be Lithocycliidae . The Lithocycliidae are distinguished from the Astracturidae due to presence of three-dimensional grid-like arms. Lithocycliidae are also distinguished from the Phacodiscidae in the absence of any exterior structure excepting a simple, circular solid edge. Differing from the distinguishing characteristics of the family Lithocycliidae ; Amphicyclia, Cromyatractus and Heliostylus possess two polar primary radial beams connected by the polar radial spines and a spindle-shaped second inner shell which is connected to the innermost shell by a few radial beams. These three genera are to be separated from the Lithocycliidae . The drawings of Astrostaurus , Crucidiscus and Staurocyclia show a crisscrossing of four radial beams in the third shell, but these structures have not been observed in an actual specimen. Heliodiscus (Heliodiscidae) is sometimes confused with Heliosestrum due to the presence of equatorial radial spines, but the former genus has a characteristically different microsphere that is unusually located in the second inner shell. It should be noted that the Lithocycliidae is an extinct family whereas the Heliodiscidae is a living family. Moreover, overall images of Heliosestrum can be distinguished from Heliodiscus by the observed lateral profile of the cortical and pore patterns ( Suyari & Yamasaki 1987: pl. 3, fig. 15; 1988: pl. 3, fig. 14). Scanning electron images of Heliosestrum are also similar to those of Lithocyclia , but the latter tends to have an increased number of systematically arranged pores on the cortical shell and lattice margin ( Suyari & Yamasaki 1988: pl. 8, fig. 14).

VALIDITY OF GENERA

Cromyatractus

Cromyatractus and Cromyatractum have the same type species. Cromyatractus has two medullary shells and two cortical shells whereas Caryatractus is marked by three or more elliptical lattice shells ( Campbell 1954: D70). As displayed by the supporting images for Cromyatractus and Cromyatractum, the number of shells is different in ontogenetic stages and/or following preservation. All these available genera are established in the same publication ( Haeckel 1887: 334 for Cromyatractus , 335 for Cromyatractum and 336 for Caryatractus ), the valid genus is objectively decided to be Cromyatractus because the remaining two available names are established as subgenera of Cromyatractus under Article 24.1 of ICZN (1999).

Heliosestrum

The combination of Astrosestrum and Astrosestantha , and that of Heliosestrum and Heliosestantha have respectively the same type species. The differences among the genera we synonymize here are the number of radial spines on the margin of the shell, the state of development of a solid equatorial girdle, a spiny or smooth cortical shell ( Campbell 1954: D78 for Astrosestrum and Heliosestrum and D82 for Astrophacura ). These characteristics were regarded as intraspecific variations in numerous papers. Astrosestrum and Heliosestrum are the oldest available name published in 1882. Hollis (1997: 41) acted as a first reviser to validate Heliosestrum .

Phacostaurus

The combination of Phacostaurus and Phacostaurium , of Crucidiscus and Staurentodiscus , and of Sethostaurus and Sethostaurium is based respectively on the same type species. Phacostaurus is characterized by a simple margin ( Campbell 1954: D79), Astrostaurus by a solid equatorial girdle or a corona of tiny by-spines ( Campbell 1954: D80), Crucidiscus by internal centripetal rods ( Campbell 1954: D79), Sethostaurus by a simple medullary shell and a simple margin ( Campbell 1954: D81), and Heliostaurus by a solid equatorial girdle ( Campbell 1954: D81). As other genera in the Lithocycliidae , the state of development of the solid equatorial ring and the tiny by-spines are intraspecies variations. However, the presence of internal centripetal rods may be different among genera. Four oldest available names were simultaneously published in Haeckel (1882: 457 for Phacostaurus , Astrostaurus , Sethostaurus and Heliostaurus ). As there are no fundamental differences among them, we selected Phacostaurus which is well illustrated in Haeckel (1887).

Sethostylus

The combined Phacostylus and Phacostylium , and the combined Sethostylus and Sethostylium have the same type species, respectively. Amphicyclia is characterized by two solid spines, no chambered arms, and double medually shells ( Campbell 1954: D82); Phacostylus by a margin of the disc with two opposite radial spines and a double medullary shell ( Campbell 1954: D78, 80); Sethostylus by a disc with a simple margin, two opposite radial spines and a simple medullary shell ( Campbell 1954: D78, 81). A thick cortical shell such as in Sethostylus prevents any observation of the innermost shell. As far as we read the distinguishing morphological characteristics written in Campbell (1954), nothing appears different among these three genera except for the connection between a radial spine and the outer medullary shell. Amphicyclia , Phacostylus and Sethostylus were established in the same publication ( Haeckel 1882: 485, 457, in ascending order). Nobody had used Amphicyclia except Kozur & Mostler 1972 in a wrong way; however, Sethostylus has been used by Petrushevskaya & Kozlova (1972: 522) and even they considered Phacostylus a junior synonym of Sethostylus . In such case Sethostylus has priority over Amphicyclia .

Triactiscus

The illustrations of the type species of Triactiscus and Trigonocyclia show obviously different internal structures but no specimens supporting the illustration of Trigonocyclia were found. Triactiscus is an available name older than Trigonocyclia .