Archaeodictyomitra conicoscalaris 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 : 141

Archaeodictyomitra conicoscalaris Dumitrică n. sp.

Fig. 14a

1981 Pseudodictyomitra formo s a Squinabol – Schaaf, p. 436, pl. 3, fig. 9.

1988 Archaeodictyomitra pseudoscalaris (Tan Sin Hok) – Thurow, p. 398, pl. 7, fig. 14.

1988 Archaeodictyomitra sp. cf. A. puga Schaaf – Thurow, p. 398, pl. 7, fig. 15, non pl. 6, fig. 18.

1995 Dictyomitra pseudoscalaris (Tan) sensu Schaaf – Baumgartner et al., p. 186, pl. 5927, fig. 4, non figs. 1, 3, 5.

Description. Shell of 7 or more segments consisting of two parts: a conical proximal part and a distal cylindrical one. Whole skeleton costate with 8-9 strong and uninterrupted longitudinal costae separated by large intercostal furrows and radiating from cephalis. On cylindrical part costae scalariform in lateral view. Nine costae visible on half perimeter. Boundaries between segments marked by a transversal row of larger pores situated between the base of a previous segment and the beginning of the new one. Sparse pores also on the constricted part of segments.

Studied material. A single specimen.

Holotype. Figure 14a , sample OZ839, coll. MGP-PD, stub PD120 -OZ839- R01-13 .

Dimensions. Total height with 7 segments 153 µm, maximum diameter 87 µm.

Etymology. From its conical shape and the scalariform outline of middle and distal segments.

Remarks. This species is part of a group of taxa with longitudinal, uninterrupted costae and a row of circumferential larger pores under each intersegmental internal wall and usually also a row of commonly smaller pores above this wall. It differs from A. coniforma Dumitrică, 1997 by being shorter and having two different outlines: rather widely conical in the proximal part and almost cylindrical in the last two to three segments.

Occurrence. A single specimen in OZ 839.

Figures

Fig. 14 a - Archaeodictyomitra conicoscalaris Dumitrică n. sp., OZ839. b, f - Archaeodictyomitra humerosa Dumitrică n. sp.: b - OZ834, f - OZ824. c - Archaeodictyomitra pumila Dumitrică n. sp., OZ834. d, e - Archaeodictyomitra conica (Aliev), OZ824. g - Thanarla cf. pulchra (Squinabol), OZ825. h - Thanarla pulchra (Squinabol), OZ839. i, j – Mictyoditra thiensis (Tan), OZ836. k - Archaeodictyomitra excellens (Tan), OZ839. l - Archaeodictyomitra sp., OZ836. m, n - Loopus nudus (Schaaf): m - OZ838, n - OZ834. o - Loopus cf. primitivus (Matsuoka & Yao), OZ834. p, p1, p2 - Svinitzium depressum (Baumgartner), p1, p2 - details of penultimate segmental band showing relic pores of parvicingulid type or other types, OZ824. Figs. r, t - Svinitzium (?) irregulare Dumitrică n. sp.: r - OZ 836, t - OZ834. s, u - Pseudodictyomitra cf. carpatica (Lozynyak): s - OZ834, u - OZ 824. Figs. b, n x250, the others x300.