Humerocyrtis lahmi, 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 : 67

Humerocyrtis lahmi n. sp.

Figs. 8f

Diagnosis. Skeleton dicyrtid bell-shaped, relatively large with hemispherical cephalis and a robust axial three-bladed apical horn with well-developed thin blades. Ventral horn, broken off, but should be shorter than the apical horn. Thorax divided into two parts (proximal and distal) by a thin circumferential ridge. Its pores are rather wide and arranged intercalately in seven circumferential rows. Its proximal half wide cylindrical and distal half flared. It bears seven circumferential rows of rounded or elliptical pores of relatively equal sizes. Distal border probably straight and thin.

Studied material. One specimen in sample Rh03.

Holotype. Fig. 8f , lost.

Dimensions. Height of shell with apical horn 220 µm, of distal part of thorax 127 µm, diameter of cephalis 48 µm, of shoulder 109 µm, of distal end 156 µm.

Etymology. The species is dedicated to Dr. Berhard Lahm for his excellent study of the Middle and Upper Triassic radiolarians from Recoaro ( Italy) and Grossreifling ( Austria).

Remarks. By its general morphology and size and especially the presence of the circumferential ridge on the shoulder and the number of circumferential rows of pores, this species resembles very much Humerocyrtis superba n. sp., from which it differs by having the thoracic pores with practically similar shapes and sizes.

Stratigraphic range. Very rare in the lower Ladinian, Buchenstein Formation, Recoaro area.

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.