Humerocyrtis brevithorax, 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 : 71-72

Humerocyrtis brevithorax n. sp.

Fig. 9d, d 1 , e; 10b, d

Diagnosis. Shell dicyrtid and very short consisting of cephalis, the shoulder plus a short portion of its narrowing distal segment. Cephalis with sparse small pores of various shapes bearing a massive and slightly curved conical apical horn and a straight, three-bladed, and well-developed ventral horn. Thorax short, represented especially by its shoulder and a short narrowing distal part. Proximal part wide and short conical bearing large circular or oval pores separated by narrow and irregularly disposed intervening bars. Circumferential ring separating the two parts of the thorax is marked either by a protruding ring, an imperforate zone, or by no special structure. Distal part of thorax is thinner-walled, very short, narrowing very fast, and its pores are smaller and irregular in size, shape and arrangement. Its distal end is usually frayed, as if not finished.

Studied material. Four or five specimens, two in the Pelsonian , one in the lower Ladinian from sample R78 /1, and one (poorly preserved), or two, in sample Rc4 .

Holotype. Fig. 9e , CRH, Cristian, coll. MGL.110296.

Dimensions. Maximum length of shell without apical horn 80 µm, maximum diameter of thorax 97-112 µm.

Etymology. From the Latin brevis – short and thorax due to its short thorax.

Remarks. This species differs from the other species of this genus by having a very short and narrowing distal part of thorax, a conical apical horn and a three-bladed ventral horn.

Stratigraphic range. Samples CRH, R78/1 and Rc4, middle Anisian (Pelsonian) to lower Ladinian (Fassanian) of Eastern Carpathians and Buchenstein Formation, Recoaro area, North Italy.

Figures

Fig. 9. a, b, f. – Humerocyrtis gracilis n. sp.: a. – paratype, Rc4; b. – holotype, BV 85-70, f.– Rc4. c. – Humerocyrtis avirostrum n. sp., Rc4; d, d1, e. – Humerocyrtis brevithorax n. sp., CRH: d, d1. – same specimen in lateral and basal view, respectively, showing the initial spicule without D ray, e. – holotype. Scale bar of 50 µm is for all figures, except fig. 7c for which the scale bar is of 75 µm.

Fig. 1. Geological map of the locality Cristian area, Braşov Mountains, Romania, modified from the geological maps Zărneşti and Braşov sheets, scale 1:50000, Săndulescu et al. (1972).

Fig. 10. a – Humerocyrtis infinita n. sp, Rc4. b, d – Humerocyrtis brevithorax n. sp.: b – R78/1b, d – poorly preserved specimen, Rc4. c – Humerocyrtis asymmetrica n. sp., Rc4. f – Humerocyrtis marmoladensis n. sp., BV 85-70. e, g – Humerocyrtis mediotriassica n. sp.: e – CR25, g – Rc4. Scale bar of 50 µm is for all figures.