Tethysetta cingulifera Dumitrică, 1997

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 : 146

Tethysetta cingulifera Dumitrică, 1997

Figs. 15 j-l

1997 Tethysetta cingulifera Dumitrică in Dumitrică et al., p. 48, pl. 9, figs. 13, 14, 17.

Description. Shell very small, ovoid, consisting of about 8 segments. The first 4 segments increase constantly in diameter forming a conical portion of the test with no circumferential ridge between cephalis and thorax and between thorax and abdomen but with a possible shallow one between abdomen and first postabdominal chamber. The pores are irregularly disposed on thorax, but they start to show the characteristic disposition in 3 alternately disposed circumferential rows on the abdomen. Fifth and sixth chambers, which are the thickest, are well marked by their ring-shaped outline with concave shape, and by three well pronounced circumferential ridges that mark their boundary with neighbouring segments and between them. Ridges slightly nodular. Distal parts inverted conical but only partly preserved in the examined samples. Better preserved specimens from Oman (Dumitrică et al., 1997) prove that the last chambers decrease rapidly in diameter, and the last one is short, inverted conical and closed distally.

Studied material. Three illustrated specimens in sample OZ838 (coll. MGP-PD, stub PD120-OZ838-R04-02) and two in sample OZ839, coll. MGP-PD, stub PD120- OZ839-R02-04 and PD120-OZ839-R02-11.

Dimensions. Length of incomplete shell 143-156 µm, maximum diameter 93-106 µm.

Remarks. Hori (1999, p. 96) erroneously included this species, as well as T. ovoidala Dumitrică and T. pygmaea Dumitrică and many others in the synonymy list of what was considered before him as Parvicingula boesii (Parona, 1890) . In such a way he extended the range of P. boesii from Kimmeridgian to Albian considering it a quite long-ranging and polymorphous species, and, therefore, biostratigraphically useless. Actually, in this stratigraphic interval the parvicingulids of the Tethys evolved rather quickly and diversified very much. In fact, the taxonomy of Parvicingula boesii is not perfectly known. Surely, it is not a Parvicingula but a Tethysetta because it has a different cephalic morphology. Under the name Dictyomitra boesii, Parona (1890, pl. 6, fig. 9) illustrated an elongate spindle-shaped species with 6 circumferential ridges. Until now almost no species illustrated in modern literature resembles perfectly Parona’s drawing.

Range and occurrence. Upper Berriasian-?lower Valanginian, Masirah Island, ( Oman) and upper Valanginian of Sardinia.

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.