Tethysetta reducta 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 : 148

Tethysetta reducta Dumitrică n. sp.

Figs. 15 f-h

Description. Shell small, long-ovate to spindle-shaped of which about two proximal thirds are conical and the distal third inverted conical. Cephalis small, spherical, without apical horn and imperforate. Postcephalic segments increasing in diameter as added up to about two thirds of length forming a conical body, then decreasing gradually. Distal end incompletely preserved and probably open as the holotype suggests. Whole shell except cephalis with small and dense circular or subcircular pores disposed alternately and divided transversally by rather irregular circumferential ridges into about 10 segments. Circumferential ridges weakly marked, partly almost indistinct. Between them each segment has only two circumferential rows of pores. Surface of test rather irregular due to the circumferential ridges and shorter oblique or longitudinal ridges.

Studied material. Three illustrated specimens in OZ836 ( PD120 -OZ836- R08-08 ), OZ838 (holotype) and OZ839 ( PD120 -OZ839- R02-08 ) .

Holotype. Figure 15g , coll. MGP-PD, stub PD120 - OZ838- R04-01 .

Dimensions. Length 149-169 µm, maximum diameter 82- 94 µm.

Remarks. The assignation of this species to the genus Tethysetta is somewhat questionable because of the very weak outside expression of the circumferential ridges, of their irregularities and of the presence of only two rows of pores in each segment.

Etymology. From the Latin reductus, - a, - um, = reduced, due to the reduced number of circumferential pores in each segment from three (normal for the genus) to two.

Occurrence. Upper Valanginian of Sardinia as far as known .

Figures

Fig. 15 a - Pseudodictyomitra nodocostata Dumitrică, OZ839. b-e - Tethysetta usotanensis (Tumanda): b - OZ837, c, d - OZ836, c1 - details of pore morphology, e - OZ838. f-h - Tethysetta reducta Dumitrică n. sp.: f - OZ836, g - OZ839, h - OZ834. i - Tethysetta ovoidala Dumitrică, OZ836, i1 - details of pore morphology. j-l - Tethysetta cingulifera Dumitrică: j - OZ838, k, l - OZ839. m - Favosyringium affine (Rüst), OZ834. n - Favosyringium cf. affine (Rüst), fragment of shell, OZ836. o - Favosyringium quadriaculeatum Steiger, fragment of shell, OZ838. p-t - Pseudoxitus seriola Dumitrică: p - OZ839, r-t - OZ836. Figs. a-I, m-t x250, figs. j-l x300.