Praeconosphaera antiqua (Parona, 1890)

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 : 108

Praeconosphaera antiqua (Parona, 1890)

Figs. 7 b-d

1890 Conosphaera antiqua Parona , p. 149, pl. 1, fig. 10.

1973 Actinommids, gen. and sp. indet. – Foreman, p. 272, pl. 1, figs. 3, 4, 6.

1982 Praeconocaryomma sp. – Okamura & Uto, pl. 4, fig. 1, not 2.

?1993 Praeconosphaera multiconus Yang , p. 104, pl. 17, figs. 8, 20.

Description. Cortical shell spherical, tuberculate, tubercles rounded pyramidal.

Studied material. Three specimens in samples PD120 - OZ825- R12-19 , PD120 - OZ834- R09-26 and PD120 - OZ838- R05-13 .

Dimensions. Diameter of shell 165-185 μm.

Remarks. Although generally it is not easy to assign specimens illustrated under scanning electron microscope to species illustrated in thin sections by Rüst (1898), Parona (1890) and others, it seems that the specimens shown in the three figures represent the species illustrated by Parona from Cittiglio, Lombardy, Italy. This species differs from Praeconosphaera sphaeroconus (Rüst, 1898) by being smaller and, especially, by having less rounded tubercles, and their top with intervening bars, which are also of the same thickness as those of the intertuberculate areas.

Range and occurrence. Tithonian to Valanginian or younger, Tethys.

Figures

Fig. 7 a - Praeconosphaera sphaeroconus (Rüst OZ826. b-d - Praeconosphaera antiqua (Parona): b - OZ834, c - OZ838, d - OZ825. e - Tritrabs ewingi (Pessagno), arm in lateral view, OZ836. f-h - Emiluvia chica Foreman, OZ836; f - face view, g - lateral view from a spine, h - lateral view of a broken specimen showing the medullary test. i - Pantanellium sp. 1, OZ825. j, l-n1 - Pantanellium squinabolli (Tan): j - OZ834; l, m - OZ834, n - OZ836; m1, n1, details of inner wall of pores. k - Pantanellium sp. 2, OZ834. o – Pantanellium cf. squinaboli (Tan), OZ836; p - Praeconocaryomma copiosa Wu, OZ836. r - Praeconocaryomma thurowi Dumitrică n. sp., OZ836. s, t - Triactoma tithonianum Rüst, side views; s - OZ834, broken off specimen showing medullary shell; t - OZ825, equatorial view, t1 – face view; s1, t2 - detail of the base of spines of figs. s and t, respectively, x800. Figs. a-h, l-n x200; i-k, o-r x300; s, t x400, m1, n1 x500.