Colpotrelus campanuliformis, 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 : 57

Colpotrelus campanuliformis n. sp.

Figs. 2f, g

Diagnosis. Shell very small, dicyrtid. Cephalis with a robust and long conical apical horn with pointed distal end. Cephalis globular with smooth surface and partly poreless or with small pores on its basal part. Initial spicule without dorsal ray. Ventral spine very small and conical. Collar boundary not marked by a constriction; it could be situated at the level where the shell starts becoming conical and where the pores increase in size and frequency. Thorax conical in the proximal part, with a well-marked circumferential ridge. Beyond it, shell is very short and cylindrical or inverted conical. Its pores are circular or oval, sparse and of various sizes.

Studied material. Two specimens in Rc4.

Holotype. The specimen from the sample Rc4, fig. 2g, coll. MGL.110271.

Dimensions. Total length with apical horn 100-115 µm, without horn 53-75 µm, diameter of cephalis 38-39 µm, of the circumferential ridge 69-77 µm, of distal segment 62-66 µm.

Etymology. From the campanulate shape of its shell.

Remarks. This species differs from the species of the other genera herein described by the very small size of its ventral spine, the absence of a three-bladed morphology of the apical horn, and its massive structure.

Stratigraphic range. Lower Ladinian.

Figures

Fig. 2. a-d. – Silicotintinnabulum formosum n. sp.: a, a1, b. – sample Rc4; a1. basal view of fig. a. showing the initial spicule without D ray; c. – paratype, FÖ 87; d. – holotype, Rc1. 2e. – Silicotintinnabulum transitum n. sp., holotype, Rc4; f, g. – Colpotrelus campanuliformis n. sp., Rc4. Scale bar of 50 µm is for all figures.