Archaeodictyomitra longipora 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 : 136

Archaeodictyomitra longipora Dumitrică nov. sp.

Figs. 13l, p

Description. Shell long spindle-shaped consisting of six or seven segments and 10 longitudinal costae visible on half a perimeter. Cephalis thin-walled, probably rounded at its top but not preserved. It is separated from thorax by a circumferential row of very small pores. Thorax and two or three post-thoracic segments increasing slowly in diameter and length and trapezoidal in lateral projection. The following two segments are slowly decreasing in diameter but not in length. Distal end without costal projections and perpendicular to the axis of shell. Costae well marked and intercostal zones broad, each one with one raw of circular to, mostly, elongate or very elongate pores. What is interesting in this species is that the middle part of grooves, wherein the pores are open, is raised, so that the deepest zones of the intercostal areas are situated on both sides of the line of pores ( Fig. 13l ). Intersegmental boundaries very weakly marked externally by wide and shallow constrictions.

Studied material. A single specimen in sample OZ836.

Holotype. The illustrated specimen, coll. MGP-PD, stub PD120 -OZ836- R08-20 .

Dimensions. Preserved length 193 μm, maximum diameter, at approximately the middle of the shell 75 μm.

Etymology. From its elongate pores.

Remarks. This very rare species differs from Archaeodictyomitra sardoa nov. sp., to which it is morphologically very close, by slightly ellipsoidal shape and elongate pores in the raised central part of grooves.

Occurrence. A single specimen in S’Ozzastru samples.

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.