Spinicingula ceratina Kozlova and Vishnevskaya, 2012

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 : 788

Spinicingula ceratina Kozlova and Vishnevskaya sp. nov.

Figs. 4H , 6B–E .

1994 Parvicingula sp. D ; Kozlova 1994b: pl. 5: 1–4.

Etymology: From Latin ceratinus, horned.

Holotype: VNIGRI N 667/66 (see Fig. 6B ).

Type locality: Borehole 5, Narjan−Mar , Timan−Pechora region, Russia. Type horizon: Middle – Upper Volgian .

Diagnosis.—Parvicingulid−like skeleton without or with weakly developed circumferential ridges, bearing 1 apical and 4–6 additional spines.

Description.—Test subconical with 4 (or more?) post−abdominal segments, slightly undulating in outline. Cephalis together with thorax dome shaped, with short apical horn and outer spines. Segments slightly increasing in width and being constant in height. All segments separated internally by planiform ring−shaped portions. Test wall thick, subpolygonal to oval pore frames arranged in transverse rows in three rows per segment. Circumferential external ridges weakly developed or not developed. Pores relatively equal in size. Abdomen and following segments trapezoidal or X−shaped in cross section. Spine A conical, often very thick, spine V thinner, between A and V one large pore. Spines D and L extend outwards from near base of thorax (D) or near base of cephalis (L) as toothshaped wings, short, smooth, oval in cross section. Spines L short and rather small. Two short, cone−shaped smooth thorns in the middle portion of the cephalis, spines ”l”.

Measurements (in µm).—Total height 120–125, maximum width 93–100, height of cephalis and thorax together 35–42.

Remarks.—Differing from species of Parvicingula in having weakly developed circumferential ridges (or altogether absent) and in possessing spines next to or surrounding the massive apical horn.

Geographic and stratigraphic range.— Middle and Upper Volgian of Pechora Basin of Russia and Upper Volgian of Volga Basin of Russia.

Figures

Fig. 4. Scanning electron micrographs of Late Jurassic radiolarians from siliceous clay rocks in northern Russia, Barents offshore. Sample 234, Middle Volgian (Dorsoplanites panderi Ammonite Zone) of the Pesha River Basin, borehole 234 (A–C, E–G, I–T). Sample G2, Late Volgian (Craspedites subditus Ammonite Zone) of the Uljanovsk Volga Basin, species from siliceous clay rocks in northern Russia, section Gorogische (D, H). A. Pentalastrum sp., GIN N 234−R−15. B. Praeconocaryomma hexagona (Rüst, 1898), GIN N 234−R10. C. Stylartus sp., GIN N 234−R12. D. Stichocapsa devorata arctica Vishnevskaya and Murchey, 2002, GIN N G−2−R1−3. E, F. Hagiastridae. E. GIN N 234−R11a. F. GIN N 234−R11b. G. Orbiculiforma? retuza (Kozlova, 1971), GIN N 234−R13. H. Spinicingula ceratina Kozlova and Vishnevskaya sp. nov., GIN N G−2−R1−5b. I. Praeparvicingula aff. sencilla Hull, 1995, GIN N 234−R21. J, M. Parvicingula cf. jonesi Pessagno, 1977. J. GIN N 234−R18b. M. GIN N 234−R18c. K. Parvicingula jonesi Pessagno, 1977, GIN N 234−R18a. L. Parvicingula blowi Pessagno, 1977, GIN N 234−R16. N. Parvicingula cf. grantensis Pessagno and Whalen, 1982, GIN N 234−R19b. O. Praeparvicingula holdsworthi (Yang, 1993), GIN N 234−R17. P. Parvicingula cf. obstinata Hull, 1995, GIN N 234−R23b. Q. Stichocapsa sp., GIN N 234−R27. R. Parvicingula rothwelli Pessago, 1977, GIN N 234−R24. S. Praeparvicingula rotunda Hull, 1995, GIN N 234−R25. T. Parvicingula alata Kozlova and Vishnevskaya sp. nov., GIN N 234−R1−2.

Fig. 6. Scanning electron photomicrographs of Late Jurassic radiolarians from siliceous clay rocks in northern Russia, Barents Sea region. A–F from Kozlova (1994b). A. Quasicrolanium planocephala (Kozlova, 1976), uppermost Volgian, Kolguev offshore, borehole 140, sample 140, VNIGRI N 140−667/41a. B–E. Spinicingula ceratina Kozlova and Vishnevskaya sp. nov. B, C. From Narjan−Mar, borehole 5, Upper Volgian, sample 5. B. Holotype, VNIGRI N 667/66. C. VNIGRI N 667/66−1. D, E. From Upper Volgian, Gorodishce section (Craspedites subditus ammonite Zone) of Uljanovsk Volga Basin, sample G2. D. GIN N G−R1−1. E. GIN N G−R1−2. F, G. Parvicingula alata Kozlova and Vishnevskaya sp. nov., Middle Volgian, Gorodishce section (Dorsoplanites panderi Ammonite Zone) of Uljanovsk Volga Basin, sample G1. F. Holotype, GIN N G−1−2Ka. G. GIN N G−1−3K. H. Parvicingula papulata Kozlova and Vishnevskaya sp. nov., holotype, GIN N P−1K. Pechora Basin, Ukhta section, sample P, Lower Kimmeridgian. Scale bars 50 µm.