Homunculodiscus tribullatus, Dumitrica, 2019

Dumitrica, Paulian, 2019, Cenozoic Spumellarian Radiolaria With Eccentric Microsphere, Acta Palaeontologica Romaniae 15 (1), pp. 39-60 : 41-42

Homunculodiscus tribullatus nov. sp.

Figure 3 a-d

Description. Shell disc-shaped and very thin consisting of two parallel porous plates interconnected by numerous transversal bars, some of them interconnected by equatorial bars forming inside short arches of different orientations. Microsphere eccentric, small with circular pores separated by thin intervening bars. Deuteroconcha consisting of two spherical unequal chambers sensibly smaller than the microsphere and attached at the antapical part of the latter. Pores of disc circular, densely distributed quincuncially and radially. Connections between the two porous plates by transversal bars distributed irregularly and, in places, in short arches. Periphery irregular, frayed, with short thin spines representing prolongations of the inner radial structures.

Material. Two specimens in upper lower Paleocene , DSDP 21-208- 30 CC .

Holotype. Fig. 3a, c , coll. MGL 103556 .

Dimensions. Diameter of shell 133-190 μm, of microsphere 17-18 μm.

Etymology. In Latin from having 3 balls (bulla) (microsphere and two of the deuteroconcha).

Remarks. Presence of the two practically similar specimens in the type sample suggests that they are not variation of the other two Paleocene species but an independent species resulted from the evolution of the Homunculodiscus nascens n. sp. This species differs from H. nascens nov. sp and H. cauleti nov. sp. by the two spherical and well-defined chambers of deuteroconcha.

Range and occurren ce. Upper lower Paleocene, DSDP 21-208-30 CC, north Lord Howe Rise, southwestern Pacific.

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.