Persiella, Schlagintweit & Rashidi, 2017

Schlagintweit, Felix & Rashidi, Koorosh, 2017, Persiella Pseudolituus N. Gen., N. Sp., And Flabelloperforata Tarburensis N. Gen., N. Sp., Two New Larger Benthic Foraminifera From The Upper Maastrichtian Of Iran, Acta Palaeontologica Romaniae 13 (2), pp. 3-19 : 7-11

Genus Persiella n. gen.

Type species: Persiella pseudolituus n.sp.

Origin of the name: Referring to Persia.

Horizon and locality: Late Maastrichtian limestones of the Tarbur Formation of the Naghan section ( Fig. 2 ).

Diagnosis: Test free, planispirally-involute or rarely streptospirally enrolled in the early stage, and biumbilicate, may become uncoiled in the late growth stage with few chambers. The protoconch is rather large, subspherical to elliptical, and connected to the second chamber

(?deuteroconch) by multiple openings. There are up to two and a half whorls present, increasing continuously in height; test periphery broadly rounded. Septa strongly oblique and perforated by numerous (cribrate) large openings. Wall dark microgranular to finely agglutinating, with thin imperforate epiderm underlain by a layer of fine, parallel, and unbranching pseudokeriotheca-like pores. Exoskeleton (beams and rafters) thick, deep and rather widely spaced, forming a network; no endoskeleton. In tangential sections, the subepidermal meshwork displays a rounded pattern. Foramen basal to multiple in the juvenile stage, later multiple.

Comparisons: The agglutinating benthic foraminifer Loftusia Brady co-occurring with Persiella n. gen. in the Tarbur Formation, has large, fusiform, ovoid or globular test, planispirally enrolled with increasing elongate coiling axis. Besides exoskeleton, Loftusia also possesses an endoskeleton ( Loeblich and Tappan, 1987, p. 110). Worth mentioning that Persiella n. gen. has been confounded in the literature with a representative of Loftusia (see synonymy and comments for the species). Both, Paracyclammina Yabe (Late Jurassic) and Pseudocyclammina Yokoyama (Late Jurassic-Late Cretaceous) possess a strongly agglutinated wall with coarse subepidermal net work and lack the layer of fine and simple alveoles of Persiella n. gen. ( Fig. 8 ). From morphological and structural view points, however, Pseudocyclammina is very close to Persiella n. gen., and could be its potential ancestor as the latter seems to be more advanced. It is worth mentioning that the youngest record of Pseudocyclammina is from the late Campanian ( Parente, 1994, pl. 1, fig. 5).

Zagrosella also with a pseudo-kerotheca-like wall structure that has recently been described from the same locality as Persiella n. gen. (see Schlagintweit and Rashidi, 2017a) differs from the latter above all by the absence of a subepidermal network (exoskeleton), thick septa with just a few rather large openings, and last but not least the presence of few thin and irregularly distributed pillars. Persiacyclammina , also described recently from the Tarbur Formation ( Schlagintweit and Rashidi, 2017b) differs from Persiella by its morphology (subcylindrical to elongate), wide chamber lumen, foraminal pattern (numerous small and rather close-set openings), and the type of exoskeleton. The latter is delicate and related also to pseudotriangular shaped radially arranged subepidermal septula stretching downward to the chamber floor.

Figures

Fig. 2 Location of the Naghan and Mandegan sections, the type localities of Flabelloperforata tarburensis n. sp., and Persiella pseudolituus n. gen., n. sp. (taken from google maps)

Fig. 8 Schematic drawing showing differences in the wall structure of Persiella n. gen. and Pseudocyclammina Yokoyama (without scale).