Type species:Spongosaturnalis ? hexagonus Yao, 1972 (OD)
Description:Ring and outer spines strongly bladed. Outline of ring hexagonal to octogenal [sic] or subquadratically rounded. 4-8 very strong outer spines. Two massive polar spines opposite to interspine spaces on the outer margin of the ring. No auxiliary spines. Ring often a little constricted in the polar spine attachment region. Cortical shells spongy, widely separated from the inner margin of the ring. Medullary shell latticed.
Remarks:By increase of the number of marginal spines the hexagonal to octogonal outline of the ring is transformed to a polygonal to subcircular one. In this manner the genus Spongosaturnalis Campbell and Clark, 1944b, evolved in the Cretaceous from Hexosaturnalis n.gen. Praehexasaturnalis n.gen. from the Norian has the same outline of ring, but the polar spines are still situated opposite to the marginal spines and the narrow ring is still flat to shallow oval in cross section. Yaosaturnalis n.gen. has the same outline and structure of ring as Hexosaturnalis n.gen., but auxiliary spines are present.
Stratigraphic range:Bajocian to Late Cretaceous, Mesozoic.
Etymology:According to the outline.
Subsequent descriptions:?

Description and dimensions:Spongosaturnalid with subhexagonal ring, and with six strong spines on ring. Shell not preserved, but believed to be wholly spongy because numerous fragmentary thorns, which may be connected with spongy shell, are clearly observed on sturdy spines. Polar spines short, thick, with no ridge. Ring bilaterally symmetrical, subhexagonal, strong, with clear ridge on outer edge. Inner edge of ring curves rather smoothly, while outer edge is subhexagonal, with spine at each vertex. Ring which joins with polar spine bends slightly toward inside. Spines, situated diagonally on ring, strong, somewhat long, of sharp tip, with clear ridges which continue to one on outer edge of ring.        (Based on 6 specimens) Diameter of ring along polar spines 156-243µm, Diameter of ring, transversely 188-282µm, diameter of shell 75-136µm, length of polar spine 10-25µm. Remarks:This species differs from Spongosaturnalis ? septispinus in the number of the spine, and from S. ? minoensis in lacking auxiliary spines on the inner margin of the saturnalin ring. Spongosaturnalis ? sp., reported by Foreman (1971, pl.1, fig.4; Cretaceous sediments core, Site 61, west margin of East Mariana Basin, through the Deep Sea Drilling Project), is similar to this species, but the former has slender spines on which there is no ridge.

Repository:Holotype: OCU No. 2041 (IN 11-12, 10/81), Department of Geosciences, Faculty of Science, Osaka City University, Japan.
Type locality:Manganese carbonate ore, Mino Belt, river side of the Kiso, east of Unuma, Kagamihara City, Gifu Pref. Central Japan.
Original stratigraphic range:[No information given]
Etymology:[Probably after the hexagonal symmetry]
Subsequent descriptions:?

Literature cited:- Campbell, A. S. and B. L. Clark (1944b). Radiolaria from Upper Cretaceous of Middle California. Geological Society of America Special Paper 57: 1-61.
- Foreman, H. P. (1971). Cretaceous Radiolaria, Leg 7, DSDP. Initial Reports of the Deep Sea Drilling Project. E. L. Winterer, W. R. Riedel et. Al. Washington, D.C., U. S. Government Printing Office. 7: 1673-1693.
- Kozur, H. and H. Mostler (1983). The polyphyletic origin and the classification of the Mesozoic saturnalids (Radiolaria). Geologisch - Paläontologische Mitteilungen Innsbruck 13(1): 1-47.
- Yao, A. (1972). Radiolarian fauna from the Mino Belt in the northern part of the Inuyama Area, Central Japan, Part I: Spongosaturnalids. Journal of Geosciences, Osaka City University 15: 21-65.