Archaeodictyomitra robustovum 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 : 138

Archaeodictyomitra robustovum Dumitrică n. sp.

Fig. 13c

1994 aff. Thanarla conica (Squinabol) – O’Dogherty, p. 90, pl. 5, fig. 25, non 23, 24, 26, 27.

Description. Shell short, ovoid, with 8-9 costae visible on half the perimeter. Apical end rather rounded, not prolonged into a small conical body distinct from the rest of the shell. Costae robust and intercostal grooves wide with circular or slightly transversally elongated pores. Apical end with an angle a little wider than 90°. Distal end not prolonged into a narrow and thinner distal neck or in lamellar projections.

Studied material. A single specimen from sample OZ837. Holotype. Fig. 13c , coll. MGP-PD, stub PD120 -OZ837- R06-21 .

Dimensions. Length 142 µm, maximum diameter 98 µm.

Etymology. From its ovoid shape ( ovum in Latin) and robustus - robust body.

Remarks. This species differs from all the other congeneric taxa of the studied assemblages by its robust shell, not acute apical end and the absence of a distal neck. The middle Aptian species illustrated by O’Dogherty ( 1994) on his fig. 25 resembles very well this species, the other specimens he illustrated under this species from middle Albian being much longer.

Occurrence. A single specimen in the sample OZ837 and one from the middle Aptian illustrated by O’Dogherty (l. cit.).

Figures

Fig. 13 a, b - Apiaromitra apiarium (Rüst): a - OZ836, b - OZ839, a1 - detail of ornamentation of last segment, b1 - detail of ornamentation of penultimate segment. c - Archaeodictyomitra robustovum Dumitrică n. sp., OZ837. d - Archaeodictyomitra sp., OZ839. e, f - Archaeodictyomitra mitra Dumitrică: e - OZ838, f - OZ824. g-k - Archaeodictyomitra massarii Dumitrică n. sp.: g - OZ834, g1 - detail of surface x1000. h - OZ834, i - OZ839, j - OZ834, k - OZ839; k1 - detail of wall showing the cavernous structure, k2 - detail of surface. l, p - Archaeodictyomitra longipora Dumitrică n. sp., OZ836; l - portion of surface of p much magnified showing the elevated intercostal area. m - Apiaromitra tyaughtonensis (Cordey), OZ837. n, t - Archaeodictyomitra dienii Dumitrică n. sp.: n - OZ836, t - OZ837. o - Thanarla cf. pulchra (Squinabol), OZ824. r - Archaeodictyomitra judae Dumitrica n. sp., OZ839. s - Archaeodictyomitra humerosa Dumitrică n. sp., OZ839. Figs. a, b x250, k1 and k2 x450, all the others x300.