SPONGOSPHAERIDAE Haeckel, 1862

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 : 418-419

Family SPONGOSPHAERIDAE Haeckel, 1862

Spongosphaerida Haeckel, 1862: 239, 452 [as a tribe]; 1882: 455 [as a subfamily]. — Mivart 1878: 177 [as a subsection]. — Stöhr 1880: 119 [as a family].

Spongosphaeria – Dunikowski 1882: 187 [as a subfamily].

Spongosphaerinae – Mast 1910: 177. — Popofsky 1912: 93, 111. — Hollande & Enjumet 1960: 68, 97. — Anderson 1983: 51, 57. — Cachon & Cachon 1985: 287 [with wrong authors as Hollande & Enjumet].

Spongosphaera – Hertwig 1937: 22-25 [as a group].

Spongosphaeridae – Hollande & Enjumet 1960: 68, 95, 96. — Anderson 1983: 50, 57. — Cachon & Cachon 1985: 286. — van de Paverd 1995: 104 [with wrong authors as Hollande & Enjumet].

TYPE GENUS. — Spongosphaera Ehrenberg, 1847: 54 [type species by subsequent monotypy: Spongosphaera polyacantha Müller, 1856: 487 ].

INCLUDED GENERA. — Diplospongus Mast, 1910: 61 . — Spongodendron Hollande & Enjumet, 1960: 99. — Spongosphaera Ehrenberg, 1847: 54 (= Hexadoridium n. syn.; Spongosphaeromma synonymized by Kozur & Mostler 1979: 10).

NOMEN DUBIUM. — Spongioconcha.

DIAGNOSIS. — Thick spongy spherical cortical skeleton with a single or double medullary shell and a variable number of threebladed radial spines.

Protoplasm is well observed in Spongosphaera . Endoplasm of brownish gray color, filling a spongy shell. Dark brownish red to reddish brown granular pigments surround the surface of the endoplasm. Axopodia radiate throughout the endoplasm. Algal symbionts are scattered on the endoplasm. Axopodial system of centroaxoplastidtype: the Axoplast is a very small fused point, located within the inner microsphere (inner double medullary shell). Nucleus is located inside the outer medullary shell or is found wrapping it. Significant bundles of axoneme are not present. Instead of bundles, axoneme radiate evenly throughout the intracapsular zone.

STRATIGRAPHIC OCCURRENCE. — early Middle Miocene-Living.

REMARKS

The genus Spongosphaera is characterized by a double medullary shell and straight three-bladed radial spines. We place the genera Diplospongus and Spongodendron into Spongosphaeridae based on the presence of three-bladed radial spines, although both genera seem to have a single medullary shell. As Spongosphaera streptacantha is typically found in plankton samples from tropical to subtropical oceans, many observations were related as well as personally observed. S. streptacantha is the only Spumellaria whose images can be captured in the ocean with an autonomous visual plankton recorder (A-VPR) ( Nakamura et al. 2017: fig. 2.C). Thus, its taxonomic stability and oceanographic response are important. The number of radial beams of this species is varies from six to twelve, its internal structure was also illustrated in detail ( Kurihara & Matsuoka 2004). By referring to this case, other genera belonging to Spongosphaeridae presumably have significant variations. The fine protoplasmic structure was illustrated in Diplospongus ( Hollande & Enjumet 1960: pl. 6, figs 4-9), Spongodendron ( Hollande & Enjumet 1960: pl. 6, figs 1-3; pl. 7, fig. 5) and Spongosphaera ( Hollande & Enjumet 1960: pl. 9, figs 8-10; pl. 22, figs 8, 9; pl. 23, figs 1, 2; pl. 24, fig. 2; pl. 26, fig. 4). An image of living forms was illustrated for Spongosphaera ( Cachon et al. 1989: fig. 1; Matsuoka 2007: fig. 5.a; 2017: figs 6.1, 6.2; Matsuoka et al. 2017: appendix A). According to Cachon (1964), “ Spongosphaera ” is infected with Hollandella myceloides , but it is impossible to amend the taxonomic name for the host without having a more complete image. Spongosphaera streptacantha can exceptionally survive in high temperatures (> 30°C) in the Malacca Strait ( Zhang et al. 2020) and is also regularly found in 17.1-19.4°C in the Japan Sea ( Kurihara & Matsuoka 2010). This is the only one species with this very wide range of survival sea water temperature.

VALIDITY OF GENERA

Spongosphaera

Morphological variation of Spongosphaera was well illustrated in many previous studies ( Kurihara & Matsuoka 2004; van de Paverd 1995: pl. 28, figs 2, 5-7). Hexadoridium is characterized by two concentric medullary lattice shells and a spongy octahedral shell ( Campbell 1954: D60). As the specimen identifiable as Hexadoridium streptacanthum is regarded as Spongosphaera polyacantha form streptacantha by van de Paverd (1995: pl. 2, fig. 2), Hexadorium is a synonym of Spongosphaera . Spongosphaeromma is characterized by two medullary lattice shells surrounded by a cortical shell bearing many radial spines ( Campbell 1954: D68). Nishimura & Yamauchi (1984: 33) seems to be the first paper to illustrate the type species Spongosphaeromma as “ Spongosphaera helioides ” and this morphological character fits with not only the definition of Spongosphaeromma but also the variation in Spongosphaera . Spongosphaera is the oldest available name among them.