Humerocyrtis contraria, Dumitrică, 2024

Dumitrică, Paulian, 2024, New Middle Triassic Bell-Shaped Nassellarian Radiolaria From Alpine And Carpathian Areas, Acta Palaeontologica Romaniae 20 (1), pp. 51-75 : 68

Humerocyrtis contraria n. sp.

Fig. 8a

Diagnosis. Test relatively short, bell-shaped with three-bladed, robust and pointed apical horn. Ventral horn pointed relatively long by comparison with other related species. Cephalis practically imperforated except a few very small pores at its lower part. Collar boundary difficult to distinguished but it could be considered to be under the level of the median bar where the pores become larger. Thorax with shoulder well marked by a rather acute angle in lateral view. Distal part of thorax very short, with a rather deep concavity under the shoulder followed by a flare-shaped outline. Distal border irregular, with a beginning of a thin additional wall developed in antapical direction.

Studied material. A single specimen in sample Rc4.

Holotype. Fig. 8a , sample Rc4, coll. MGL.110289.

Dimensions. Total length of shell 140 µm, of thorax 60 µm, diameter of shoulder 71 µm, of distal end of thorax 90 µm.

Etymology. From the Latin contrarius, - ia – contrary, because its ventral spine is longer than that of other species of the genus Humerocyrtis with similar morphology.

Remarks. This species resembles most of the small species of the genus Humerocyrtis with three-bladed apical horn by its general shape, but differs from them by having a longer and more robust ventral horn, thoracic pores with very variable sizes and irregular arrangement. It differs also by its irregular distal thoracic border.

Stratigraphic range. Very rare in the sample Rc4 from the Buchenstein Formation from Recoaro, North Italy.

Figures

Fig. 8. a. – Humerocyrtis contraria n. sp., holotype, Rc4; b. – Humerocyrtis conica n. sp., holotype, Rc4. c. – Humerocyrtis jekeli n. sp., holotype, Rc2; e,?d.– Humerocyrtis undulata n. sp., Rc4: e – holotype. f – Humerocyrtis lahmi n. sp., holotype, Rc4. Scale bar of 50 µm is for all figures.