STYLOSPHAERIDAE Haeckel, 1887

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 : 459-460

Family STYLOSPHAERIDAE Haeckel, 1887

sensu Dumitrica (1985)

Stylosphaerida Haeckel, 1887: 121 [as a family], 133 [as a subfamily]. — Rüst 1892: 141 [as a family]. — Anderson 1983: 23 [as a family].

Stylosphaeridae – Haecker 1908: 440. — Popofsky 1912: 83. — Clark & Campbell 1942: 24; 1945: 11. — Campbell & Clark 1944a: 10; 1944b: 4. — Frizzell & Middour 1951: 12. — Deflandre 1953: 417. — Campbell 1954: D53. — Chediya 1959: 78. — Orlev 1959: 433. — Zhamoida & Kozlova 1971: 79. — Tan & Su 1982: 141. — Dumitrica 1984: 98; 1985: 185. — Chen & Tan 1996: 150. — Tan 1998: 121. — Tan & Chen 1999: 144. — De Wever et al. 2001: 117. — Bragin 2007: 889. — Bragin 2011: 753. — Matsuzaki et al. 2015: 10. — Chen et al. 2017: 124. — Dumitrica & Hungerbühler 2017: 88.

Stylosphaerinae – Clark & Campbell 1942: 24; 1945: 11. — Campbell & Clark 1944b: 4. — Frizzell & Middour 1951: 13. — Campbell 1954: D53. — Kozur & Mostler 1979: 15; 1984: 118. — Afanasieva et al. 2005: S273. — Afanasieva & Amon 2006: 110. — Bragin 2007: 889. — Bragin 2011: 753.

Stylosphaerids – Sugiyama et al. 1992: 11.

TYPE GENUS. — Stylosphaera Ehrenberg, 1846: 385 [type species by monotypy: Stylosphaera hispida Ehrenberg, 1854b: 246 ]

INCLUDED GENERA. — Druppatractona Haeckel, 1887: 326 . — Lithatractona Haeckel, 1887: 322 . — Spongatractus Haeckel, 1887: 350 (=? Spongoprunum n. syn.; Spongoxiphus synonymized by Sanfilippo & Riedel 1973: 519). — Stylosphaera Ehrenberg, 1846: 385 (= Stylosphaerella with the same type species; Stylosphaerissa n. syn.).

NOMINA DUBIA. — Lithatractium, Lithatractylis, Stylosphaeromma.

DIAGNOSIS. — The skeleton consists of one to three concentric shells and two prominent polar spines (that may be absent in older species). The skeleton may also consist of one to three concentric shells with a cluster of shorter polar spines instead of one prominent polar spine. A single or double internal shell is present, the innermost shell is always of ovoid or pyriform shape. The outermost shell is robust and latticed, or made by fine spongy layer. It is of spherical to ellipsoid shape and is connected to the inner shells by many radial spines. The polar spine is usually three-bladed (cylindrical in rare cases) and originates from the innermost shell. The polar spine that joins the sharp end of the pyriform inner shell tends to be shorter than the opposite polar spine. Intraspecific variability, reveals a spectrum of morphotypes differing by having numerous radial beams from the opposite side of the pyriform inner shell, which give rise to the radial spines. Additional radial secondary spines may sometimes be present on the external shell.

STRATIGRAPHIC OCCURRENCE. — Late Campanian-Living.

REMARKS

The Stylosphaeridae are externally similar to the Axoprunidae and Stylatractidae by them having two prominent polar spines. The former family is distinguishable from the Axoprunidae in that the latter has cylindrical polar spines, and microbursa-type microspheres (see remarks for Heliosaturnaloidea ). Stylosphaeridae is also different from the Stylatractidae due to its spherical innermost shell. The genera belonging to the Stylosphaeridae can be identified by the number of shells and the type of the polar spines (cylindrical or three-bladed). It is only possible to differentiate Lithatractona from Stylatractona (Stylatractidae) by an examination of the innermost shell. The number and length of radial spines are variable at species level. This is recognized in the late Eocene to early Middle Miocene Stylosphaera radiosa ( Gorbunov 1979: pl. 2, figs 2a-2e; Nakaseko 1955: pl. 2, fig. 6; pl. 3, fig. 1; pl. 4, fig. 6; pl. 5, figs 1, 4; Suzuki et al. 2009d: pl. 1, figs 9, 10) and in the extant Stylosphaera pyriformis ( Takahashi 1991: pl. 15, fig.12-14; Itaki & BjØrklund 2007: pl. 6, figs 9-13; Nishimura 2015: pl. 11, figs 2-5, 7, 8; Chen et al. 2017: pl. 15, figs 18-21; pl. 28, figs 12-16; pl. 30, figs 8-10; pl. 35, figs 12-19). These observations were possible by the presence of co-occurring variable forms in a single sample. The number and length of radial spines are an important characteristic at genus level but need to be carefully examined. Internal structure for Druppatractus ( Nakaseko & Nishimura 1982: pl. 20, fig. 2) and Stylosphaera ( Nakaseko & Nishimura 1982: pl. 19, fig. 4; pl. 21, figs 1, 3; pl. 24, figs 1, 4; Nishimura 1982: pl. 2, figs 1-7; Sugiyama & Furutani 1992: pl. 15, figs 2, 6, 7) was well illustrated.

VALIDITY OF GENERA

Spongatractus

The synonymy between Spongatractus and Spongoxiphus was well established by Sanfilippo & Riedel (1973). Any real specimen identifiable as Spongoprunum , the type species of Spongoprunum , have not been so far illustrated. Spongoprunum is tentatively synonymized with Spongatractus due to the occurrence of their spongy elongate shells. Spongatractus , Spongoprunum and Spongoxiphus were simultaneously published in Haeckel (1887: 350 for Spongatractus , 347 for Spongoprunum , and 353 for Spongoxiphus ). In respect to the first reviser rule, Spongatractus is selected as a valid genus between Spongatractus and Spongoxiphus .

Stylosphaera

Stylosphaerella has the same type species as Stylosphaera . Stylosphaerissa is defined by two concentric lattice shells, irregular pores with dissimilar sizes, no by-spines or thorns on the surface ( Campbell 1954: D53). The specimen most similar to the illustration of Stylosphaera nana ( Haeckel 1887: pl. 16, figs 12, 13) was found in an upper Paleocene to lower Eocene sample from the Pacific Ocean (supporting image of Stylosphaerissa ). Based on this specimen, all morphological features, except the shape of the inner shell, do exactly match between them. The real sample has a pyriform inner shell and subsequently Stylosphaerissa is a synonym of Stylosphaera . The oldest available genus is Stylosphaera .