Bibradya densicamerata sp. nov.

Figure 8A‒F

zoobank.org/ CC448745-8DBE-4E77-923B-DBDF19EC8679

Derivation of the Name. For the numerous chambers in the juvenarium.

Material. Holotype (HPU-KC75-488, Figure 8B) and twenty-five paratypes (Table 3).

Repository. School of Resources and Environment, Henan polytechnic University .

Type Locality and Horizon. Kacai section, Tarusian (early Serpukhovian).

Occurrence. From the top of the Mikhailovian to the top of the Serpukhovian.

Diagnosis. Large Bibradya with a juvenarium densely packed composed of numerous quadratic chambers and a rapid expansion in the final 1.5 whorls composed of more rounded and irregular chambers.

Description. Large test composed of 3‒4 whorls for mature specimens, ranging from 1300‒1500 μm. Coiling is irregular throughout, changing progressively the plane, and increasing rapidly the evolution rate in the final 1.5 whorls. The height of the lumen in the final chamber reaches 320‒720 μm, with a H/D ratio of 0.2‒0.41. Chambers are numerous in the inner whorls, approximately 7‒8 in the second whorl, and 8‒12 in the fourth whorl. Septa are straight in the inner whorls and blunt with an incipient bifurcation in the final whorl. Wall microgranular. Cribrate aperture composed of multiple elements present in the entire apertural zone.

Remarks. Species differs from B. tenella (Figure 8G‒I) by the distinctively compressed juvenarium, more chambers, and higher number of whorls.