Persiella pseudolituus, 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 : 11

Persiella pseudolituus n. sp.

Figs. 3C–D , pars, 9–12, 13D–F

2013 Loftusia morgani – Pirbaluti et al., Fig. 8.10 Origin of the name: The species name refers to seemingly similarities to the species Pseudocyclammina lituus Yokoyama.

Holotype: Almost centered axial section illustrated in Figure 12G , thin-section SNSB-BSPG 2016 V 16 (original thin-section Rt 113).

Paratypes: Specimens in figs. 9A–G, 10, 11A–B, F, H, M.

Description: Test free, subglobular (coiled forms) to elongate (uncoiling forms), early stage planispirally (occasionally streptospirally, Fig. 11a ) coiled and involute with up to two and a half whorls present. The test periphery is broadly rounded; with slight axial depressions on both sides (biumbonate). The protoconch is rather large, subspherical to elliptical, and connected to the second chamber (?deuteroconch) by multiple openings ( Fig. 12j ).

Chambers increasing continuously in width and only moderately in height, with many as thirteen chambers in the final whorl. In the coiled part, the septa are strongly oblique with five to six chambers in the first, and ten to eleven chambers in the second whorl. Only rarely the adult stage is uncoiling, uniserial and rectilinear with at least up to six chambers ( Fig. 9e–f ). Here the septa are convex, in direction of growth. Exoskeleton (beams and rafters) coarse, deep, and forming a network that in tangential sections displays a rounded pattern ( Fig. 12a–b, f ). Foramen basal to multiple in the juvenile stage, later multiple. In some sections it appears as that the foramina are disposed in continuity between successive chambers ( Fig. 12 f, i ). No endoskeleton present. Wall dark microgranular (?to finely agglutinating), with thin imperforate outer layer (epiderm) underlain by a layer of fine, parallel, and unbranching pseudokeriotheca-like pores.

Dimensions (in mm):

equatorial diameter (uncoiling forms) = up to 2.5

axial diameter (thickness) = up to 1.35

ratio ed/ad (uncoiling forms) = 1.5–1.9 (juvenile specimens ~1.2)

height (uncoiling forms) = up to 3.0

diameter proloculus = up to 0.65 (mostly 0.25–0.45) thickness septa = 0.075–0.15

diameter foramina = 0.035 –0.075

thickness epidermis = ~0.0075

wall thickness (epidermis + fine alveolar layer) = 0.04– 0.065

diameter parapores = 0.0075 –0.015

Remarks: Persiella pseudolituus has been confounded one time with Loftusia morgani Cox (see synonymy). L. morgani is a large size foraminifer (up to 44.5 mm in length and up to 8 mm in diameter), morphologically different, with endoskeleton, just a name a view differences (e.g., Cox, 1937; Meriç and Görmüş, 2001.). From a morphological aspect and also general appearance in sections, Persiella pseudolituus shows similarities with the Late Jurassic to earliest Cretaceous Pseudocyclammina lituus (Yokoyama) ( Fig. 13 ). Leaving apart the generic differences, the test of P. lituus is more compressed (ratio equatorial diameter/axial diameter about 2), the proloculus is smaller (0.24–0.26 mm), and the number of chambers in the last whorl are less (5–6; all data acc. to Hottinger, 1967, p.63).

Figures

Fig. 3 Typical microfacies of samples with Flabelloperforata tarburensis n. gen., n. sp (F in a–b), and Persiella pseudolituus n. gen., n. sp. (Ps in c–d), from the upper Maastrichtian Tarbur Formation of the Naghan section, Zagros Zone, SW Iran. a–b Wackestones/packstones with benthic foraminifera, among many porcelaneous and agglutinating taxa such as Dicyclina sp. (Di), Tarburina zagrosiana Schlagintweit, Rashidi & Barani (T), Dictyoconus bakhtiari Schlagintweit, Rashidi & Babadipour (D) and remains of dasycladalean algae (d in b). c Wackestone with small and larger benthic foraminifera and oblique longitudinal section of the dasycladale Pseudocymopolia cf. anadyomenea (Elliott) (P). d Grainstone/packstone with Omphalocyclus macroporus Lamarck (O), Dictyoconella? minima Henson (Dic), and slightly oblique axial section of Persiella pseudolituus n. gen., n. sp. (Ps). Thin-sections: 2NG 81-4 (a), 2NG 120 (b), 2NG 166 (c), 2NG 177 (d).

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

Fig. 12 Persiella pseudolituus n. gen., n. sp. from the upper Maastrichtian of the Tarbur Formation of the Mandegan (a, g, i–j) and Naghan sections (all others), Zagros Zone, SW Iran. a–e, h–i Oblique sections; note the rounded outline of the network in a and b. f Tangential section; note the rounded subepidermal network (lower part). g Almost centered axial section, holotype specimen. j Juvenile specimen showing protoconch connected to the following chamber (?deuteroconch) by numerous openings. Abbreviations: b = beam, p = proloculus, d? = possible deuteroconch, f = foramen, r = rafter, s = septum. Thin-sections: Rt 87 (a), NG 198 (b), 2NG 120-1 (c), 2NG 144 (d), 2NG 113 (e), 2NG 200-1 (f), Rt 113 (SNSB-BSPG 2016 V 16) (g), 2NG 200-1 (h), Rt 113-1 (i), Rt 72 (j).

Fig. 11 Persiella pseudolituus n. gen., n. sp. from the upper Maastrichtian of the Tarbur Formation of the Naghan section, Zagros Zone, SW Iran. a-b, d, g-h, m Axial sections (partly slightly oblique); note initial streptospiral coiling in a. e–f Subaxial sections. i–j: Details from f and h showing pseudokeriotheka-like wall structure. k–l Oblique sections. Thinsections: 2NG 76 (a), 2NG 120-1 (b), 2NG 152 (c), 2NG 122 (d), 2NG 153 (e), 2NG 154 (f, i), 2NG 127 (g), 2 NG 186 (h, j), 2NG 152-1 (k–l), NG 3-1 (m).

Fig. 9 Persiella pseudolituus n. gen., n. sp. from the upper Maastrichtian of the Tarbur Formation of the Mandegan (a, e, g) and Naghan sections (all others), Zagros Zone, SW Iran. a–b Equatorial sections. c–d, g Oblique equatorial sections; note tendency to uncoil in the youngest chambers. e–f Oblique equatorial sections of uncoiling specimens. Abbreviations: p = proloculus, d = possible deuteroconch, f = foramen, s = septum. Thin-sections: Rt 113 (a, g), 2NG 191 (b), 2NG 186 (c), 2NG 49 (d), Rt 87-1 (e), NG 196 (f).

Fig. 13 Pseudcyclammina lituus Yokoyama (a–c) compared to Persiella pseudolituus n. gen., n. sp. (d–f). a, d Equatorial sections; b, e axial sections; c, f subaxial-tangential sections. From Hottinger (1967): a = pl. 10, fig. 11 (late Jurassic of Poland), b and c = pl. 10, fig. 12 and fig. 13 (topo-type from Tithonian-Berriasian Torinosu limestone, Japan).