Broeckina Munier-Chalmas, 1882

Schlagintweit, Felix & Rashidi, Koorosh, 2016, Some New And Poorly Known Benthic Foraminifera From Late Maatrichtian Shallow-Water Carbonates Of The Zagros Zone, Sw Iran, Acta Palaeontologica Romaniae 12 (1), pp. 53-70 : 57-61

Genus Broeckina Munier-Chalmas, 1882

Remarks: Loeblich & Tappan (1987) included Broeckina in the Meandropsinidae Henson. Following the emendation of this family by Hottinger & Caus (2009), Broeckina lacking a diaphanous umbo, should be removed from the Meandropsinidae as remarked by Consorti et al. (2016) instead remaining in the superfamily Soritoidea . The family status however is still uncertain.

Broeckina cf. dufrenoyi (d’Archiac, 1854)

Fig. 11

*1854 Cyclolina dufrenoyi n. sp. – d’ Archiac, p. 205, pl. 2, figs. 1a–d.

1882 Broeckina dufrenoyi (d’ Archiac) – Munier-Chalmas, p. 471.

1975 Broeckina dufrenoyi (d’ Archiac) – Cherchi and Schroeder, p. 5, pl. 1, figs. 1–6, pl. 2, figs. 1–3, pl. 4, figs. 2, 4–6.

Description: Test flat discoidal, with annular chambers displaying an exoskeleton of radial partitions. Test wall is porcelaneous. Due to the lack of adequate sections, information on the initial part is not available (for details see Cherchi and Schroeder, 1975). The specimens attain diameter of up to 2.6 mm, and a thickness of up to 0.15 mm.

Remarks: Broeckina gassoensis from the middle Coniacian of Spain differs from Broeckina dufrenoyi by its smaller size and different evolution of the septula (for further details see Caus et al., 2013). According to Caus et al. (2013), the type-species B. dufrenoyi should be restricted to the late Santonian–early Campanian. The occurrence of Broeckina cf. dufrenoyi (d’Archiac, 1854) in the late Masstrichtian of the Tarbur Formation is therefore of special interest. It is recorded from both Mandegan and Naghan sections where it appears in the uppermost part of the sections.

Genus Cuvilierinella Papetti & Tedeschi, 1965

Remarks: A modern generic diagnosis was provided by Vicedo et al. (2011).

Cuvillierinella ? sp.

Fig. 12

Remarks: Rare and very poorly preserved specimens were observed in a comparatively narrow interval of unit 3 of the Mandegan section. The oblique to subaxial section show general similarities to Cuvillierinella salentina described by Papetti & Tedeschi (1965) from the Campanian of southern Italy (see also Vicedo, 2011). Cuvillierinella is known from the middle Campanian to early Maastrichtian (e.g., Fleury, 2014, fig. 3; Vicedo et.al., 2011), and its occurrence in the late Maastrichtian is debatable.

Genus Spirolina Lamarck, 1804

Spirolina? farsiana n. sp.

Figs. 13–14

Holotype: Fig. 13b , Thin-section Rt 67-2.

Origin of the name: The species name refers to the Fars province of Iran.

Type locality: Mandegan section ( Fig. 2 ).

Type level: Late Maastrichtian of the Tarbur Formation.

Diagnosis: Possible representative of Spirolina with two to three planispirally coiled whorls that may also slightly oscillate. Chamber lumen semi-lunate in equatorial and rounded-arched in axial sections. Rectilinear adult part with few chambers. Foramina simple in the planispiral part, becoming most likely cribrate with small projections (teeth?) in the uncoiled part.

Description: Test planispirally coiled in two to three whorls, each with an increasing number of chambers. Early stage most likely involute then biumbonate and semi-involute. Test periphery is rounded. Planes of coiling may slightly oscillate. As discernible in equatorial sections, the sutures are barely if ever discernible at the test surface. There are 8 to 10 chambers in the last enrolled whorl and then the test becomes uncoiled, rectilinear, more or less cylindrical in the adult part (with up to 7 chambers). In equatorial sections, the outline of the chamber lumen is mostly semi-lunate, and rounded-arched in axial sections. The septa are inclined. The foramina in the planispiral stage are simple, areal, with several tiny protrusions (teeth?) in the uncoiled stage ( Fig. 13d, g ). The wall is porcelaneous, imperforate. The inner part of the wall always is dark homogeneous, whereas the outer part often displays a light-grey finely grumbly appearance (structural differences enhanced by diagenetic alteration? agglutinated particles?).

Remarks and comparisons: The genus Spirolina has been critically reviewed by Tronchetti and Grosheny (1992) concluding that all Mesozoic representatives are highly doubtful, and that S. cretacea Tronchetti & Grosheny from the Santonian of France would be the only Mesozoic Spirolina and therefore its oldest record. Note that Loeblich and Tappan (1987) regarded the genus as Eocene to Holocene. Spirolina cretacea Tronchetti & Grosheny , is different from Spirolina? farsiana above all due to its chamber shape (more or less pyriform), the well expressed sutures, reduced number of chambers, and the costate surface ornamentation (Tronchetti and Grosheny, 1992, for details). The taxonomic uncertainty of the Maastrichtian taxon from Iran is due to the lack of test ornamentation and especially details on the aperture that is controversely discussed in the literature. According to Loeblich and Tappan (1987), Spirolina displays a terminal, rounded aperture, whereas the allied genus Dendritina d’ Orbigny (both Eocene to Holocene) has a dendritic (or stellate) aperture. A single opening as apertural type for Spirolina was recently also remarked by Sirel et al., (2013). Tronchetti and Grosheny (1992, p. 397) on the other hand united forms with either a rounded terminal aperture with numerous small teeth-like projections or forms with ramified, simple or multiple aperture. It is worth mentioning that S. cretacea possesses a multiple aperture with small teeth. An equivalent aperture seems to be present also in S.? farsiana . The presence of a dentritic aperture in S.? farsiana however cannot be excluded due to the lack of transverse section cutting the foramina in the uncoiled part. The dendritic foramina/aperture in the Paleogene taxon Paraspirolina gigantea for example shows very similar projections above the septa in longitudinal section through the uncoiled part ( Fleury, 1997, e.g., pl. 1, fig. 23, penultimate chamber!) as observed in S.? farsiana ( Fig. 13d, g ).

We note some morphological similarities of Spirolina? farsiana to the early Paleogene Kayseriella decastroi Sirel. This species differs from the former by its thick apertural tooth and peristomal rims ( Sirel, 1999). Last but not least, S.? farsiana displays also affinities to representatives of Pseudorhapydionina De Castro (e.g., De Castro, 1985; Consorti et al., 2016), but lacking septula.

Superfamily Miliolacea Ehrenberg, 1839

Family Hauerinidae Schwager, 1876

Figures

Fig. 11 Broeckina cf. dufrenoyi (d’Archiac), Late Maastrichtian Tarbur Formation of Mandegan section, Zagros Zone, SW Iran. a Fragmentary equatorial section showing septules. b–c Oblique sections showing septula. d Subaxial section. Thin-sections: SNSB-BSPG 2016 III-16 (a–b), SNSB-BSPG 2016 III-17 (c), Rt 113-2 (d).

Fig. 12 Cuvillierinella? sp., Late Maastrichtian Tarbur Formation of Mandegan section, Zagros Zone, SW Iran. a Oblique section close to axial plane. b–c Subaxial sections. sl = septulum. Thin-sections: Rt 100 (a), SNSB-BSPG 2016 III-10 (b), SNSB-BSPG 2016 III-18 (c).

Fig. 13 Spirolina? farsiana n. sp., Late Maastrichtian Tarbur Formation of Mandegan section, Zagros Zone, SW Iran. a Oblique equatorial section of specimen with uncoiled adult part. b Slightly oblique equatorial section with few uncoiling chambers; holotype specimen. c Subaxial section: Note changing growth direction of enrolled part. d Detail of e showing foramina with lip-like projections. e, f “Axial” section of the uncoiled part. g–h Subaxial sections. Note teeth-like projections in g (arrow). i, fragmentary oblique section. Thin-sections: Rt 67-3 (a, e–d), Rt 67-2 (b, h), SNSB-BSPG 2016 III-1 (c, g, i), SNSB-BSPG 2016 III-8 (f).

Fig. 14 Spirolina? farsiana n. sp., Late Maastrichtian Tarbur Formation of Mandegan section, Zagros Zone, SW Iran. a Subaxial section. b–c, f Equatorial section, partly oblique. d–e, g Subaxial, slightly oblique sections. Thinsections: Rt 67-3 (a, e), Rt 70 (b, f), Rt 86 (c), SNSB-BSPG 2016 III-3 (d), Rt 84 (g).

Fig. 2 Location map of the studied area.