Family CENTROCUBIDAE Hollande & Enjumet, 1960
Centrocubidae Hollande & Enjumet, 1960: 48, 51, 69, 120-121. — Petrushevskaya 1975: 571. — Anderson 1983: 52. — Dumitrica 1983a: 224 [in Spumellaria]; 1984: 95. — Cachon & Cachon 1985: 286 [in Order Cryptoaxoplastida]. — Kiessling 1999: 44 [in Entactinaria]. — De Wever et al. 2001: 197, 200 [in Entactinaria]. — Afanasieva et al. 2005: S278 [in Order Capsulata]. — Afanasieva & Amon 2006: 116.
Centrocubinae – Petrushevskaya 1979: 108. — Kozur & Mostler 1979:15.
TYPE GENUS. — Centrocubus Haeckel, 1887: 277 [type species by subsequent designation (Campbell 1954: D66): Centrocubus cladostylus Haeckel, 1887: 278].
INCLUDED GENERA (CENOZOIC ONLY). — Centrocubus Haeckel, 1887: 277. — Octodendron Haeckel, 1887: 279 (= Octodendridium with the same type species; Heterospongus n. syn.).
NOMEN DUBIUM. — Octodendronium.
DIAGNOSIS. — The central structure is constructed of a cubic frame and eight rays emerging from the cubic frame. The external part outside the cubic frame consists of a spherical shell made of homogenous layers of coarse polygonal meshes, or a spherical shell made of coarse polygonal meshes. Eight or more radial bladed spines are present. Eight radial spines directly arise from the eight internal rays while the remaining radial spines appear at some points of the shell and are made of coarse polygonal meshes.
The protoplasm is observed in Centrocubus. The endoplasm occupies the central part and appears as a dark brown sphere surrounded by a brownish grey ectoplasm. The ectoplasm is distributed in the inner half of the meshed shell. In regard to the axopodial system of an anaxoplastid-type; no axoplast and no bundles of axonemes are observed. The central structure is attached to the nucleus which is located at the center of the intracapsular zone. Instead of bundles of axoneme, the axoneme densely radiates throughout the endoplasm. No algal symbionts were detected.
STRATIGRAPHIC OCCURRENCE. — early Middle Miocene-Living.
REMARKS
It is nearly impossible to differentiate Centrocubus from Spongodendron and Spongosphaera (Spongosphaeridae) without an examination of its central structure. However, it may be possible to identify these species by an examination of both siliceous skeletal parts and protoplasmic characteristics. A fixed image with dyeing was published for Centrocubus (Aita et al. 2009: pl. 23, fig. 3). The living status of Centrocubus is plausible if the photo of “Ses55” specimen of Sandin et al. (2021) is compared to the pl. 23, fig. 3 of Aita et al. (2009). A specimen covered with protoplasm may appear different when observed. Living specimens of Spongosphaera, Tetrasphaera (? Spongodrymidae), Cladococcus and “ Elaphococcus ” (Cladococcidae) are well documented due to the fact that these genera are commonly found in warm shallow seawaters; such good documentation enables differentiation from Centrocubus easier. The endoplasm of Lychnosphaera (Cladococcidae) never covers the outer part of the skeleton. Consequently, it cannot be confused with Centrocubus even in living cells. However, the living status of Spongodendron has not been confirmed making difficult to compare them with living cells. The living specimen shown in De Wever et al. (1994: figs 13, 16) was identified as Octodendron but it is impossible to confirm this identification given the quality of the images. The fine protoplasmic structure was illustrated for Centrocubus (Hollande & Enjumet 1960: pl. 9, fig. 7; pl. 13, figs 1-8; pl. 26, fig. 3; pl. 60, fig. 1), and Octodendron (pl. 60, fig. 7).
The internal skeletal structure for Centrocubus was documented (Dumitrica 1983a: pl. 3, figs 1-3; van de Paverd 1995: pl. 27, figs 1, 2). The overall character of the specimen illustrated in van de Paverd (1995: pl. 26, fig. 2) is identical to Octodendron, but the central structure is probably the same as that of the Excentroconchidae. A new and undescribed genus probably belongs to this family (e.g., Aita et al. 2009: pl. 40, fig. 1; pl. 43, fig. 3). Old Centrocubidae genera such as the Triassic Arcicubulus (Dumitrica 1983a), the Jurassic Solicubulus (Dumitrica 1983a), and the Cretaceous Marianasphaera (Li & Sashida in Li et al. 2011) and Pessagnulus (Dumitrica 1983a) are also included in this family.
VALIDITY OF GENERA
Octodendron
Octodendridium has the same type species as Octodendron. Genera in the Centrocubidae are mainly classified by the construction of the microsphere, the number of rays from the microsphere, branched patterns of these rays, and relationship of rays with shells. Heterospongus is defined by branched eight main spines, cube-shaped microsphere, radial spines produced from corners (Campbell 1954: D68). Octodendron is defined by latticed cortical shell surrounded by spongy network which may bear small radial spines and no secondary radial spines (Campbell 1954: D68). Ridiculously, attention points are not overlapped each other between these definitions, it is unable to pinpoint the difference points from them. The definition of Octodendron is properly applicable for Heterospongus; on the other hand, that of Heterospongus is also properly applicable for Octodendron. This concludes the synonymy relationship even under the concept of Campbell (1954). As Octodendridium is simultaneously published as a subgenus of Octodendron with Octodendron in Haeckel (1887), Octodendron prioritized over Octodendridium as a valid name.