AXOPRUNIDAE Dumitrica, 1985

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 : 467

Family AXOPRUNIDAE Dumitrica, 1985

Axopruninae Dumitrica, 1985: 186 . — De Wever et al. 2001: 209-210. — Afanasieva et al. 2005: S280. — Afanasieva & Amon 2006: 119.

Spongostylida Haeckel, 1882: 455 [nomen dubium, as a tribe];1887: 122, 148 [as a subfamily]. — Schröder 1909: 8 [as a subfamily].

Spongostylinae – Campbell & Clark 1944a: 12 [nomen dubium]. — Frizzell & Middour 1951: 15. — Campbell 1954: D54. — Chediya 1959: 83.

Dorydiscinae Campbell, 1954: D89 [nomen dubium].

Axoprunidae – Suzuki et al. 2009d: 241. — Dumitrica et al. 2010: 287.

TYPE GENUS. — Axoprunum Haeckel, 1887: 298 [type species by monotypy: Axoprunum stauraxonium Haeckel, 1887: 289 ].

INCLUDED GENERA. — Axoprunum Haeckel, 1887: 298 (= Ellipsoxiphium n. syn., Xiphosphaerella n. syn.; Stylacontarium synonymized by Sugiyama et al. 1992: 16). — Dorylonchella Clark & Campbell, 1942: 22.

NOMINA DUBIA. — Dorylonchomma, Dorydiscus , Dorydruppa, Doryphacus, Doryprunum.

DIAGNOSIS. — Heliosaturnaloidea without equatorial ring, with two polar spines and a latticed cortical shell ( Dumitrica et al. 2010: 287). A dark grey endoplasm fills the medullary shell and is additionally observed in its surrounding periphery.

STRATIGRAPHIC OCCURRENCE. — Early Paleocene-Living.

REMARKS

Polycystinea with a spherical to oblong shell with bi-polar spines (also present in the Stylatractidae and Stylosphaeridae ). The initial differentiation marker for Axoprunidae was based on the presence of inner non-bladed bi-polar spines. Instead, the precise identification of this family’s representatives should be based on the presence of a microbursa. Skeletal structure, including growth line, was documented for Axoprunum ( Dumitrica 1985: pl. 3, figs 19, 20; Nishimura 1986: fig. 7.3; Sugiyama & Furutani 1992: pl. 16, figs 9, 11; Sugiyama et al. 1992: pl. 12, fig. 4; Vasilenko 2019: pl. 1, fig. 6). A “ living” image for the Axoprunum collected in the Mesopelagic zone ( Suzuki & Not 2015: fig. 8.10.14) was documented. The last occurrence of “ Axoprunum ” angelinum ( Campbell & Clark 1944a), as senior synonym of “ Stylatractus ” universus Hays 1970 ”, is dated as 0.46 ± 0.04 Ma age in the Pacific ( Matsuzaki et al. 2014; Kamikuri 2017), Atlantic ( Morley & Shackleton 1978) and Southern Ocean ( McIntyre & Kaczmarska 1996). Notwithstanding, no appropriate genus has been proposed for this species (e.g., Nakaseko & Nishimura 1982: pl. 12, figs 3, 4; Dumitrica 1985: pl. 3, figs 16-18; Sugiyama et al. 1992: pl. 13, fig. 3).

VALIDITY OF GENERA

Axoprunum

The central part of the type species for Axoprunum is missing in the type-illustration ( Haeckel 1887: pl. 48, fig. 4), but all other characters, except the central part, are sufficient to specify this genus of the Cenozoic. The definition of Axoprunum in Campbell (1954: D68) is useless because his definition did not include the probable presence of internal shell(s), the presence of six radial beams whose pairs are perpendicular to each other, and the presence of two un-bladed similar opposite polar spines. These characters are fully or partly overlooked in the definition of the remaining genera in Campbell (1954: D54 for Xiphosphaerella , D60 for Stylacontarium and D69 for Ellipsoxiphium ) so that they are useless to understand the differences between these genera. The internal structure is invisible in the type-illustrations for Ellipsoxiphium ( Haeckel 1887: pl. 14, fig. 7) as well as Xiphosphaerella ( Haeckel 1887: pl. 14, fig. 4), but the occurrence of a completely empty shell has not been clearly proved in these two genera. The definition of Xiphosphaerella includes the presence of a papillose to spiny or thorny surface, but this characteristic is not significant (supporting image for Xiphosphaerella ). Until the exact internal structures of Xiphosphaerella and Ellipsoxiphium are documented, the four genera discussed here are regarded as synonyms. Axoprunum , Ellipsoxiphium and Xiphosphaerella were simultaneously published by Haeckel (1887: 124 for Xiphosphaerella , 296 for Ellipsoxiphium and 298 for Axoprunum ). Axoprunum is validated because this is the only genus whose internal structure is illustrated in images of the type.