Cribrospira evoluta, 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 : 12-13

Cribrospira evoluta sp. nov.

Figure 7A‒E

zoobank.org/ 4E4E8AC1-3316-4FFE-9A0D-B60FFF00D9C3

Derivation of the Name. From the evolute final whorl.

Material. Holotype ( HPU-KC58-1 , Figure 7A ) and ten paratypes ( Table 2 ).

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

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

Occurrence. Upper part of the Mikhailovian (late Viséan) to basal Zapaltyubian (late Serpukhovian) in the Shuidong section and Venevian‒Tarusian in the Kacai section.

Diagnosis. Large Cribrospira with a high evolution rate in the final whorl, a mixture of septa (curved, furrowed, swollen), inner whorls irregularly coiled, and only the final whorl trends to be planispiral.

Description. Free large test with a diameter of 1200‒1600 μm for specimens of 2.5‒3 whorls. A juvenile specimen measures 940 μm in diameter for 1.5 whorls. Coiling irregular nearly up to the final whorl that becomes planispiral. The final whorl is located in a plane about 90º from the first whorl. Septa are usually blunt, swollen, and furrowed, but in the final chambers, they can be pointed, containing a relatively high number of chambers (9‒12 in the final whorl), with marked sutures in the final chambers and smooth inner ones. The evolution rate progresses uniformly in the inner whorls, and rapidly in the final whorl, which a height of the lumen in the final chamber between 450 and 600 μm, with high H/D ratios of 0.33‒0.40. Wall microgranular, comparatively thin, 20‒50 μm in the final chamber. Cribrate aperture in the entire apertural face.

Remarks. The species presents intermediate features between Cribrospira (nearly planispiral final coiling and curved septa) and Bibradya (more skew-coiled inner whorls and furrowed/swollen septa), allowing to distinguish from other species of Cribrospira and Bibradya .

Figures

FIGURE 7. Illustrations of the new species Cribrospira evoluta sp. nov. A. HPU-KC58-7 (holotype), B. HPU-KC77-1, C. HPU-SDB155-2, D. HPU-SDB181-4, E. HPU-SDB191-215. (Scale bar equals 1 mm).