Spumellaria Ehrenberg, 1875

Vishnevskaya, Valentina S. & Kozlova, Genrietta E., 2012, Volgian and Santonian-Campanian radiolarian events of the Russian Arctic and Pacific Rim, Acta Palaeontologica Polonica 57 (4), pp. 773-790 : 786

Order Spumellaria Ehrenberg, 1875 Family Sponguridae Haeckel, 1862 Genus Spongurus Haeckel, 1862

Type species: Spongurus cylindricus Haeckel, 1860 , Recent, Pacific ocean.

Spongurus arcticus Kozlova and Vishnevskaya sp. nov. Fig. 7A–C .

Etymology: In reference to the Arctic Realm.

Holotype: GIN K22−2−57 (see Fig. 7A ).

Type locality: Borehole 22, Ust−Manja, western Siberia, Russia.

Type horizon: Lower Campanian, Upper Cretaceous.

Diagnosis.—Elongated monoaxonic skeleton of small or average sizes, subrectangular in outline, with increased in width polar tips, without patagium and terminal spines.

Description.—Stick−shaped cylindrical spongy skeleton extending along one axis, covered by spongodiscid texture. Skeleton consisting of three main elements: spherical central part formed by several concentric or spiral cameral rings, surrounding central microsphere, and two polar processes terminating in pole−like beams. Polar processes and spherical central part as a rule have irregular spongodiscid tissue or are sometimes spongy−porous. Pylome located at one of the poles is quite rare.

Measurements (in µm).—Length of longitudinal axis: 190; length of transverse axis: 55; pore diameter: 3–8. The skeleton varies in size along the longitudinal (170–210) and transverse (45–70).

Remarks.—The new species differs from congeners in having a cylindrical, stick−shaped subrectangular skeleton and in the absence of firm polar spines.

Geographic and stratigraphic range.—Boreal realm; Arctic Margin, Kara, and Volga basins, Russia.

Figures

Fig. 7. Scanning electron micrographs of Late Cretaceous (Early Campanian) radiolarians from siliceous rocks of the Russian Arctic Margin (western Siberia, borehole 22, Ust−Manja, sample 57), except for D which is from the Volga Basin, Uljanovsk region, Shilovka section, sample 7−1. A–C. Spongurus arcticus Kozlova and Vishnevskaya sp. nov. A. Holotype, GIN N K22−2−57. B. GIN N K22−2a−57. C. GIN N K22−2b−57. D–F. Prunobrachium articulatum (Lipman, 1952). D. GIN N K22−15a−57. E. GIN N K22−15b−57. F. GIN N K22−15c−57. G, K–N. Lithostrobus ex gr. rostovzevi Lipman, 1960. G. GIN N K22−1a−57/1.K. GIN N K22−1b−57/1. L. GIN N K22−1c−57/2. M. GIN N K22−1c−57. N. GIN N K22−1d−57. H–J. Lithostrobus borealis Kozlova and Vishnevskaya sp. nov. H. GIN N K22−1a−57. I. GIN N K22−1b−57. J. Holotype, GIN N K22−1−57. O. Lithostrobus longus Grigorieva, 1975; GIN N K22−11−57. P–R. Immersothorax marinae (Gorbovets, 1966). P. GIN N K22−12−57. Q. GIN N K22−12a−57. R. GIN N K22−12b−57. S. Amphipyndax stocki (Campbell and Clark, 1944), GIN N K22−13−57.