Becus coronatus Dumitrică, 2022

Dumitrica, Paulian, Dieni, Iginio & Massari, Francesco, 2022, Valanginian Radiolarians Of Ne Sardinia (Italy) In The Frame Of The Weissert Event, Acta Palaeontologica Romaniae 18 (2), pp. 97-159 : 113

Becus coronatus Dumitrică n. sp.

Fig. 8a

Description. Shell drum-shaped in lateral view, circular in face view, with three closely interconnected central nodes and 12 nodes disposed in a peripheral circle. Peripheral nodes interconnected by 2-4 thin bars. Space between central and peripheral nodes depressionary with irregularly disposed polygonal meshes representing the surface of the spongy skeleton of the species.

Studied material. A single specimen in OZ839.

Holotype. Fig. 8a , coll. MGP-PD, stub PD120 -OZ839- R01-01 .

Dimensions. Diameter 110-120 µm.

Etymology. From the Latin coronatus , - a, - um = crowned. Remarks. By its shape, this species resembles Becus rotula Dumitrică, 1997 , from which it differs by having a circle of 12 nodes instead of 9, three central nodes instead of one, and by lacking the three primary spines. Its superficial ornamentation with 12 peripheral nodes suggests that it originates in Becus triangulocentrum Dumitrică, 1997 , in a similar mode as Becus rotula , that is by the dissolution of the peripheral spongy test and of the spines. It is surprising that the holotype does not conserve any trace of primary spines, which are robust in B. triangulocentrum . It differs also from B. triangulocentrum by having very robust nodes. It is possible that this species represents, in fact, skeletal remains of well silicified specimens of B. triangulocentrum with dissolved superficial lateral skeleton.

Range and occurrence. Late Valanginian, S’Ozzastru section, Sardinia so far as known.

Figures

Fig. 8. a - Becus coronatus Dumitrică n. sp., OZ839. b-f1, j - Becus triangulocentrum Dumitrică, b - OZ836; c - same, lateral view, d - OZ836. e, f - OZ825, f1 - lateral view of fig. f. g - Alievium regulare (Wu & Li), OZ836. h, i, k, l - Alievium rotundum Dumitrică n. sp.: h, specimen destroyed showing internal structure, OZ836; i - OZ836, k, l - holotype, OZ834. m - Alievium incomptum Dumitrică n. sp., OZ836. n - Godia (?) lenticulata Dumitrică n. sp., OZ834. o - Godia (?) lens Dumitrică n. sp., OZ825. p - Alievium eurasicum Dumitrică n. sp., OZ825. r - Microsandwichia plana (Hori), OZ834. s, t - Spumellarian gen. et sp. indet., OZ834. figs. c, e-h, k, m, r, t x250, figs. a, b, d, i, j, l, p, s x300; figs. n, o, t x400.