Mesorbitolina parva ( Douglass, 1960 )

SCHLAGINTWEIT, FELIX, 2021, Orbitolinids And Other Larger Benthic Foraminifera From The Aptian-Albian Of Tibet: Critical Discussion Of Some Recently Published Data, Acta Palaeontologica Romaniae 18 (1), pp. 17-23 : 18

Record of Mesorbitolina parva ( Douglass, 1960)

( Fig. 1A )

Referred illustrations: Mesorbitolina parva , part of figure 8 in BouDagher-Fadel et al. (2017).

Mesorbitolina parva ( Douglass, 1960) has been described as Orbitolina (Columnorbitolina) absidata by Zhang (1986) from the Langshan Formation of the Lhasa Block. Here we make reference to a tiny image of “ Mesorbitolina parva ” included in Fig. 8 of BouDagher-Fadel et al. (2017) therein showing the stratigraphic ranges and assumed phylogenetic relationships ( Fig. 1A ). The specimen is here interpreted as an axial section of Praeorbitolina cormyi perpendicular to the median plane comparable to those illustrated by Bosselini et al. (1999, fig. 5a and 5g) from the early Aptian of Ethiopia ( Fig. 1 B-C), or own material from Iran ( Fig. 1 D-E). It shows a subdivided subembryonic zone overlain by protoconch and deuterconch; a supraembryonic zone is seemingly lacking. The regular presence of short partitions at the top of the deuteroconch (not well discernible) would indicate Praeorbitolina claveli Schlagintweit et al. This example and the following ones give evidence that the established ranges partly include incorrect determinations too.

Figures

Fig. 1. A, Mesorbitolina parva (Douglass) fide BouDagher-Fadel et al. (2017, excerpt of fig. 8), Lower Cretaceous of Tibet. B-E, Praeorbitolina cormyi Schroeder, axial sections perpendicular to the median plane (B-C: excerpt of Bosselini et al., 1999, fig. 5a and 5g, early Aptian of Ethiopia; D-E: early Aptian of Iran). Figures without scale.