Bibradya maxima, Liu & Vachard & Cózar & Coronado, 2023

Liu, Chao, Vachard, Daniel, Cózar, Pedro & Coronado, Ismael, 2023, New species and evolution of the foraminiferal family Janischewskinidae in the middle-upper Mississippian of South China, Palaeontologia Electronica (a 2) 26 (1), pp. 1-27 : 16-17

Bibradya maxima sp. nov.

Figure 10A‒E

zoobank.org/ BB49C3FF-9867-4CFA-A3DF-E4C0E1959116

Derivation of the Name. For its large size.

Material. Holotype ( HPU-KC87-4 , Figure 10D ) and eighteen paratypes ( Table 5 ).

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

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

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

Diagnosis. Giant Bibradya with a progressive evolution rate and furrowed and bifurcated septa in the final chambers.

Description. Large test composed of 2‒2.5 whorls, with a diameter ranging from 1600‒3000 μm. Coiling plane changes progressively and the final whorl is nearly planispiral, but not completely. Height of the lumen in the final chamber is 500‒1000 μm, with high H/D ratio of 0.3‒0.44, due to a progressive and rapid evolution rate in the successive whorls. The number of chambers is high, 10‒13.5 in the final whorl, whereas about half (5‒6) in the previous whorls. Septa in the juvenarium and early chambers of the final whorl are curved, whereas the final 5‒6 chambers are separated by swollen and furrowed septa, which tend to be bifurcated in the final 2‒3 chambers. Complex cribrate apertures occupy the entire apertural face.

Remarks. The most similar species is B. tenella , which presents similar number of chambers, whorls, septa, and coiling, although B. maxima is twice or three times larger.

B. maxima differs from B. densicamerata for the larger size, smaller number of whorls, and more expanded juvenarium.

Figures

FIGURE 10. Illustrations of the new species Bibradya maxima sp. nov. and Bibradya subita sp. nov. A‒E. Bibradya maxima sp. nov. A. HPU-KC75-389, B. HPU-KC75-392, C. HPU-SDB155-529, D. HPU-KC87-4 (holotype), E. HPU- KC75-41. F‒I. Bibradya subita sp. nov., F. HPU-SDB182-33, G. HPU-SDB184-301 (holotype), H. HPU-KC81-7, I. HPU-SDB173-533. (Scale bar equals 1 mm).