Cryptomanicula absconsa, Dumitrica, 2019

Dumitrica, Paulian, 2019, Cenozoic Spumellarian Radiolaria With Eccentric Microsphere, Acta Palaeontologica Romaniae 15 (1), pp. 39-60 : 51

Cryptomanicula absconsa nov. sp.

Figures 3h ; 5 a-e; 7c

Description. Shell thin, lens-shaped with circular outline. Microsphere eccentric with 3 primary rays, of which one axial (antapical) and two lateral. Angle between lateral rays much greater than between lateral rays and the axial one. Rays not prolonged outside periphery of the disc and not visible on the surface. Besides primary rays shell contains a greater number of secondary and tertiary rays originated in the first and second extramicrospheric ring, respectively ( Fig. 5c ).

Material. Three specimens in the late early Paleocene sample DSDP 21-208 - 30 CC, Lord Howe Rise, SW Pacific . Two specimens are entire (figs. 3h; 4a, 4b) and one has one surface sectioned off (figs. 5c-e) to know the internal structure of shell.

Holotype. Specimen from Figs. 5a, 5b , coll. MGL 103558 .

Dimensions. Diameter of holotype 239 μm, of paratype 260 μm, diameter of microsphere 12.5 μm, angle between lateral rays 150-155°, between lateral primary rays and axial primary ray 100-110°, distance between microsphere and apical border 100 μm, distance between microsphere and antapical border 128 μm.

Remarks. Perfection of the circular outline of this species suggests the possibility of the presence of other Paleocene species that could make the transition between it and Trimanicula penultima Dumitrică. The close relationship with this species is also suggested by the wide opening of the angle between the two lateral primary rays.

Etymology. From the Latin absconsus – hidden, because the initial skeleton of this species is hidden inside the lenticular disc and difficult to see.

Range and occurrence. DSDP 21-208-30 CC, early Paleocene, Prinsius martini nannoplankton Zone.

Figures

Fig. 3 a-d. Homunculodiscus tribulatus nov. gen., nov. sp., DSDP 21-208-30 CC; a, c – holotype; c – detail of central part of a, double magnified. b, d – paratype, d – central part of b double magnified. e, g – Homunculodiscus teinemplecta (Caulet), DSDP 21-207A-15CC; e – detail of central part of fig. g, double magnified. Fig. f, h - Cryptomanicula absconsa nov. gen., nov. sp. paratype; f – detail of surface of central part of fig. h, focused on surface, h focused on middle part, DSDP 21-208-30 CC. Scale bar for entire specimens = 50 μm.

Fig. 5 a-e - Cryptomanicula absconsa nov. gen., nov. sp.; a – holotype, b – same, central part magnified. c-e – paratype with one cortical layer struck off with a razor blade: c – general view from the surface, d – same, viewed from the struck off face, focussed on primary rays; e – same, focussed on the 7-sided initial ring. All scale bars = 50 μm