Bibradya subita, 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 : 17-19

Bibradya subita sp. nov.

Figure 10F‒I

zoobank.org/ 3BB52629-ECA6-44DC-87BD-6CA7C75CD8BC

Derivation of the Name. For the sudden change in the coiling plane of the final whorl.

Material. Holotype ( HPU-SDB184-301 , Figure 10G ) and 17 paratypes ( Table 6 ).

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

Type Locality and Horizon. Shuidong section, Protvian (late Serpukhovian).

Occurrence. Tarusian to Protvian (Serpukhovian) in both sections.

Diagnosis. Large Bibradya with the inner whorls oscillating and the final whorl changing suddenly 90º the coiling plane.

Description. Large rounded to elongated test, ranging from 900 μm for specimens of 2‒2.5 whorls, up to 2000 μm for 3.5‒4 whorls. The inner whorls are nearly planispiral, with slightly oscillations, and the final whorl turns approximately 90º rapidly. This sudden change in the coiling axis is also observed in the smaller specimens (e.g., Figure 10F, I ). The rate of evolution of the juvenarium is slow, and high rates for the final whorl. Height of the lumen in the final chamber is 210‒580 μm, with a moderate to high H/D ratio of 0.24‒0.48. Septa furrowed, swollen, and bifurcated in the final whorl, curved in the juvenarium. Chambers are numerous, 11‒13 in the final whorl, with marked final sutures. Wall microgranular, 30‒60 μm thick. Cribrate apertures occupy the entire apertural face.

Remarks. The arrangement of the final whorl with the sudden turn in the coiling plane distinguishes this species from other Bibradya .

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).