Bibradya primitiva, 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 : 14-15

Bibradya primitiva sp. nov.

Figure 9A‒F

zoobank.org/ 81CE4253-CD52-455B-B1AC-494ABFA71371

2022 Bibradya ? sp. 1― Cózar et al., fig. 10M.

Derivation of the Name. From its primitive features.

Material. Holotype ( HPU-KC81-399 , Figure 9A ) and 11 paratypes ( Table 4 ).

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

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

Occurrence. Mikhailovian (late Viséan) to Steshevian (early Serpukhovian) in the Kacai section and up to the Zapaltyubian in the Shuidong section.

Diagnosis. Small Bibradya with swollen, blunt septa, and incipient bifurcation of septa for a low evolution rate of the test.

Description. Test free, small to moderate size, 490‒890 μm for specimens of 2‒3 whorls. The evolution rate is low and in some of the final chambers is even lower, showing a lower height of the lumen than that in the previous chambers. Height in the last chamber 70‒170 μm, H/D ratio very low, 0.10‒0.17 (0.26). Coiling is irregular, changing progressively the plane, and does not present any whorl completely in the same plane. Septa are blunt, swollen, and with incipient bifurcation, separating numerous chambers, usually 9-11 in the last whorl, but 8 chambers in specimens of only 2 whorls. Wall microgranular to granular, comparatively thick for the size of the specimens (20‒30 μm). Aperture cribrate.

Remarks. Differs from B. inflata ( Figure 4F ) by a lower evolution rate, higher number of chambers, slightly higher number of whorls, less pronounced bifurcated septa, and more rudimentary cribrate apertures. The primitive characters of the species allow to distinguish it from the rest of more evolved Bibradya .

Figures

FIGURE 4. Selected primitive Janischewskinidae with granular wall or with some agglutinated grains compared with a Mstiniidae. A. Bibradya grandis Strank, 1983, DPM-PC-TQ56-1250, Urswick Limestone Formation, Trowbarrow Quarry (N. England), late Asbian (late Viséan). Microgranular wall with rare agglutinated large grains in the third and sixth septa from the aperture. B. Bibradya moldensis (Strank in Somerville and Strank, 1984), HPU-SBD179-208, Shuidong section, Protvian (late Serpukhovian). Note the granular wall, rarely with small agglutinated grains. C. Holkeria avonensis (Conil and Longerstaey in Conil et al., 1980), DPM-PC-BS68-955, Park Limestone Formation, Barker Scar section (N. England), Holkerian (middle Viséan). Granular wall throughout the test with some large agglutinated grains in septa and outer wall. D. Cribrospira pansa Conil and Lys, 1965, DPM-PC-LF26-2162, Dalton Formation, Low Frith section (N. England), ‘upper’ Arundian (lower Viséan). Microgranular wall in the inner whorls with more granular aspect in the final whorls and with common small agglutinated grains. E. Cribrospira pansa, DPM-PC-WS36-1587, Dalton Formation, White Scar Quarry (N. England), ‘top’ Arundian (middle Viséan). Microgranular wall throughout the test, with large agglutinated grains in the wall of the final chambers. F. Bibradya inflata Strank, 1983, DPM-PC-TQ84- 1954, Urswick Limestone Formation, Trowbarrow Quarry (N. England), late Asbian (upper Viséan). Microgranular wall throughout the test with some small agglutinated grains. (Scale bar equals 0.5 mm). [DPM- corresponds to the Palaeontological Collection in the Palaeontology Department of the Universidad Complutense de Madrid, PC- to the P. Cózar’s collection, the following number corresponds to the number of thin-section (e.g., TQ56, WS36, …), and the final number corresponds to the number of specimens].

FIGURE 9. Illustrations of the new species Bibradya primitiva sp. nov. A. HPU-KC81-399 (holotype). B. HPU- SDB179-291. C. HPU-SDB191-217. D. HPU-KC37-341. E. HPU-SDB176-6. F. HPU-SDB180-19. (Scale bar equals 0.5 mm).