First Middle Ordovician (Darriwilian) Foraminifers from ...

First Middle Ordovician (Darriwilian) Foraminifers from the Alborz Mountains, northern Iran Galina P. Nestell1, Mansoureh Ghobadi Pour2, 3, Hadi Jahangir4, Tatiana Yu. Tolmacheva5, Leonid E. Popov3, Andrew Hunt1 and Puloma Chakrabarty1 1

Department of Earth and Environmental Sciences, University of Texas at Arlington, Arlington, Texas 76019, USA email: [email protected]; [email protected]; [email protected] 2 Department of Geology, Faculty of Sciences, Golestan University, Gorgan 49138-15739, Iran email: [email protected] 3 Department of Natural Sciences, National Museum of Wales, Cardiff CF10 3NP, Wales, United Kingdom email: [email protected] 4 Department of Geology, Faculty of Sciences, Ferdowsi University of Mashhad, Azadi Square, Mashhad 91775-1436, Iran email: [email protected] 5 A.P. Karpinsky Russian Geological Research Institute, Sredny pr. 74, St. Petersburg 199106, Russia email: [email protected]

ABSTRACT: Middle Ordovician (Darriwilian) monothalamous agglutinated foraminifers are described for the first time from strata of the Lashkarak Formation of the Simeh-Kuh section, Alborz Mountains, northern Iran. One new genus Damghanites Nestell and Ghobadi Pour with the type species D. lashkarakensis, and three new species Amphitremoida simehkuhensis, Sorosphaera iranensis and S. darriwiliensis are described. Analysis of the foraminiferal wall of some of these species has revealed the presence of quartz, feldspar, products of feldspar degradation and rare grains of anatase, and also the presence of iron. Conodonts from the lower part of the Lashkarak Formation indicate an age within the interval of the Lenodus variabilis to Eoplacognathus? pseudoplanus zones of the lower Darriwilian (Middle Ordovician).

INTRODUCTION Foraminifers are relatively common, but an often overlooked component of the benthic Ordovician fauna. At the present time, they have been documented from all Ordovician stages except the Tremadocian and the Hirnantian. Ordovician foraminifers are known from Baltoscandia, Laurentia, the Precordillera Terrane in Argentina, and South China (Nestell et al. 2009 and Nestell et al. 2011 with references). Until now, no record of the group from the Ordovician of Gondwana has been reported. Herein, we present the first report of the occurrence of agglutinated foraminifers from Middle Ordovician (Darriwilian) strata of northern Iran. The foraminifers were recovered from two conodont samples taken from the lower part of the Lashkarak Formation at Simeh-Kuh in the vicinity of Damghan, northern Iran. MATERIAL AND METHOD

Limestone samples were dissolved in dilute (10–15%) buffered acetic acid following standard procedure, and after treatment, the residue was handpicked without using heavy liquid separation. Free tests of foraminifers were picked from residues of two samples (C-9 and C-10). All tests are white with unevenly distributed brownish patches. To analyse the composition of the test wall the authors used energy-dispersive X-ray and Raman spectroscopy analyses. Energy-dispersive X-ray spectroscopy (EDX) analysis

Microanalysis of two foraminiferal tests was undertaken using a combination of scanning electron microscopy (SEM) and en-

ergy dispersive X-ray spectroscopy (EDS). An FEI/Aspex Personal Scanning Electron Microscope (PSEM) was used for this purpose. Backscattered electron (BE) collection was used for particle imaging. Variations in BE yield correlate with particle average atomic number and composition. Individual element composition was determined by EDS using an OmegaMax™ silicon drift detector with an ultra-thin window, permitting the detection of light elements such as carbon and oxygen. The PSEM was operated in the variable pressure mode, which obviated the need to apply a conducting coat to the sample. Raman spectroscopy Three foraminiferal tests were used for confocal Raman spectroscopic analysis. The instrument in use is a Thermo ScientificTM DXRTMxi Raman imaging microscope which runs the Thermo Scientific OMNICTMxi Raman Imaging software. The analytical characterization tool is then used to capture the Raman shift from the obtained spectra at any position on the crystal. In addition, this procedure also collects a chemical image and cross-section of the desired region. The current experimental characterization technique is useful in determining the composition of a given sample under observation. The foraminifers are oriented and fixed in required positions on the stage. The samples are then analyzed and identified using 10x and 50x objectives. For the present characterization, the Raman spectrometer uses an argon ion laser of wavelength 532 nm with a power of 5.3 mW and 25 µm confocal aperture spot. The spectra are obtained (number of scans = 15) with a data acquisition time of 11 ms at 90 Hz, between a spectra window of -1 50-1500 cm .

Micropaleontology, vol. 62, no. 6, text-figures 1–5, plates 1–2, pp. 415–427, 2016

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Galina P. Nestell et al.: First Middle Ordovician (Darriwilian) Foraminifers from Alborz Mountains, northern Iran

TEXT-FIGURE 1 Geographical map of north-central Iran showing the locality of the Simeh-Kuh section northwest of Damghan, Alborz Mountains, northern Iran.

The foraminifers are composed of rare light reddish-brown crystals along with white crystals, as shown in reflected light. The Raman spectra measured on the reddish-brown and white crystals are found to be anatase (TiO 2), quartz (SiO 2) and calcite (CaCO 3). The presence of the minerals is analyzed by comparing the measured spectra with existing RRUFF library (http://rruff.info/) for Raman spectra of various minerals. The spectra collected for the different minerals under the microscope matched the standard peaks of the minerals in the library for a minimum of three peaks. GEOLOGICAL AND GEOGRAPHICAL SETTING The Simeh-Kuh section is situated in the southern foothills of the eastern Alborz Mountains northwest of the city of Damghan (text-fig. 1). This section exhibits the most complete Lower to

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Middle Ordovician succession in the region. Detailed information on the Early Paleozoic geology and stratigraphy of the area can be found in publications by Ghobadi Pour et al. (2007; 2011), Bassett et al. (2013) and Popov et al. (2016). Whereas the Tremadocian to Dapingian lithostratigraphy of the region is incomplete and still being interpreted, the Darriwilian (Middle Ordovician) to Upper Ordovician deposits are assigned to the Lashkarak Formation, as revised by Ghobadi Pour et al. (2011). In Simeh-Kuh the Lashkarak Formation, about 96 m thick, rests with a sharp, erosional contact on a condensed succession of the Floian (Lower Ordovician) to Dapingian (Middle Ordovician) limestone beds containing the brachiopod Yangtzeella and the trilobite Ningkianites (Ghobadi Pour et al. 2007; 2011).

Micropaleontology, vol. 62, no. 6, 2016

TEXT-FIGURE 2 Stratigraphic sequence of the Lashkarak Formation showing the position of samples and stratigraphical ranges of selected conodont, ostracod and trilobite species (modified from Bassett et al. 2013 and Popov et al. 2016). Dap. – Dapingian.

The lower part of the Lashkarak Formation comprises cross-bedded sandstone with brachiopod shell beds in the upper part considered to have been deposited in shoal complexes (text-fig. 2, units L18 - L19, samples C-9, C-9/1, C-9/1-2, C-9/2). The coquina accumulations are formed by disarticulated valves of the orthide brachiopod Bastamorthis multicostata

Ghobadi Pour et al. (2011). Other components of the fossil assemblage include the brachiopod Martellia? sp., trilobite Neseuretus sp. aff. N. tristani (Brongniart in Desmarest 1817), conodonts Microzarkodina hagetiana Stouge and Bagnoli 1990, Baltoniodus sp., B. cf. B. norrlandicus (Löfgren 1978), Lenodus sp., Periodon cf. P. aculeatus Hadding 1913 and Drepan-

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oistodus sp., and a few tests of the monothalamous agglutinated foraminifer Psammosphaera rugosa Eisenack (text-fig. 2, sample C-9).

following Löfgren and Zhang (2003), as its generic assignment to Lenodus is still not affirmed by the revision of the species, though it is widely named as Lenodus in recent conodont papers.

Conodonts are well preserved; however, they are rare in this stratigraphic level. Elements of M. hagetiana (Pl. 2, figs. 1-3) and Drepanoistodus sp. are among the most numerous in the sample making up to 90% of the elements of the conodont assemblage, which as a whole is represented by less than fifty elements. Considering the occurrences of M. hagetiana, B. cf. B. norrlandicus, and a few poorly preserved elements of Lenodus, the lower part of the Lashkarak Formation may be correlated with the early Darriwilian Lenodus variabilis Biozone of Baltoscandia (Löfgren and Tolmacheva 2008). M. hagetiana is well recognized by its high base and deep basal cavity and is reported from all over Baltoscandia and from southern China, from the lower part of the Lenodus variabilis Zone to the lower part of the Eoplacognathus? pseudoplanus Biozone. However, the occurrence of Baltoniodus cf. B. norrlandicus restricts the age of the assemblage to the Lenodus variabilis Biozone. These new data confirm the previous conclusion about the assignment of this part of the formation to the Lenodus variabilis Biozone (Ghobadi Pour et al. 2011).

The upper part of the Lashkarak Formation at the Simeh-Kuh

Sandstone beds are gradually replaced by a monotonous succession of intercalating fine-grained sandstone and siltstone with a few thin limestone beds considered to have been deposited in middle shelf environments (text-fig. 2, units L20 L21). Unit L21 contains characteristic limestone beds formed by dense accumulations of complete thecae of the rhombiferan echinoderm Echinosphaerites (Ghobadi Pour et al. 2011; text-fig. 2). The second foraminifer-bearing sample (text-fig. 2, sample

C-10) was recovered from a bed of limestone at 3.2 m above the echinoderm bed and at 4.7 m below the base of the bed of oolitic ironstone unit (text-fig. 2, Unit L22). The assemblage of foraminifers is represented by only monothalamous agglutinated forms of the species Amphitremoida simehkuhensis Nestell and Ghobadi Pour, n. sp., A. sp. aff. A. longa Nestell and Tolmacheva, Damghanites lashkarakensis Nestell and Ghobadi Pour, n. gen., n. sp., Psammosphaera rugosa Eisenack, Sorosphaera iranensis Nestell and Ghobadi Pour, n. sp., S. darriwiliensis Nestell and Ghobadi Pour, n. sp., and S? sp. aff. S. tricella Moreman. The foraminifers occur together with the ostracods Cerninella aryana Williams, Vannier and Meidla (Ghobadi Pour et al. 2006), Ordovizona amyitisae Williams, Vannier and Meidla (Ghobadi Pour et al. 2006) and Pariconchoprimita sp. that are the most common microfossils in the residuals. Other components of the fossil assemblage include the linguliform brachiopods Rowellella? sp. and Eoconulus sp., sponge spicules, trilobite fragments, phosphatized gastropods and bryozoans (Ghobadi Pour et al. 2007; Popov et al. 2008). Conodonts are represented by the elements of B. cf. B. norrlandicus, Eoplacognathus? pseudoplanus (Viira 1974), Drepanodus arcuatus Pander 1856, Scalpellodus gracilis (Sergeeva 1974), Venoistodus cf. V. balticus Löfgren 2006, and Drepanoistodus sp.

The occurrence of Eoplacognathus? pseudoplanus (Viira 1974) indicates correlation of the Unit L21 with the Eoplacognathus? pseudoplanus Zone of the upper part of the Kunda Regional Stage in Baltoscandia (Löfgren 2000). This species is provisionally referred herein to Eoplacognathus? pseudoplanus

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section consists of a bed of oolitic ironstone (text-fig. 2, unit L22) and up to 55 m thick intercalating fine-grained sandstone and siltstone (text-fig. 2, units L23, L24) with abundant echinoderms, including Echinosphaerites sp., Heliocrinites sp., Sinocystis sp., and Tholocystis sp. (Lefebvre et al. 2005), brachiopods Bellimurina fluctuosa Popov, Kebriaee-Zadeh and Ghobadi Pour 2016, Ishimia inflata Popov, Kebriaee-Zadeh and Ghobadi Pour 2016, Lepidomena multiplicata Popov, Kebriaee-Zadeh and Ghobadi Pour 2016, Rogorthis? oriens Popov, Kebriaee-Zadeh and Ghobadi Pour 2016, and Pseudocrania insperata Bassett, Ghobadi Pour, Popov and Kebriaee-Zadeh 2013, and bryozoans of latest Darriwilian age (Bassett et al. 2013; Popov et al. 2016). The upper contact of the Lashkarak Formation in the studied transect is faulted against Carboniferous rocks. SYSTEMATIC PALAEONTOLOGY

The authors use the system of higher taxa of Protozoa proposed by Cavalier-Smith (2002), higher taxa of foraminifers proposed by Mikhalevich (1998), and classification of monothalamous agglutinated foraminifers on order and family level proposed by Kaminski (2014). All illustrated taxa of foraminifers and conodonts are deposited in the Department of Geology, Azad University, Esfahan (AEU), Iran, in the collection under number AEU/L5501- AEU/L5534. Kingdom PROTOZOA Goldfuss 1817; emend. Owen 1858

Subkingdom GYMNOMYXA Lankester 1878 stat. nov. emend. Cavalier-Smith 2002 Infrakingdom RHIZARIA Cavalier-Smith 2002 Phylum RETARIA Cavalier-Smith 1999 stat. nov. Cavalier-Smith 2002 Subphylum FORAMINIFERA (d’Orbigny 1826) Eichwald 1830 stat. nov. Margulis 1974; stat. emend. Cavalier-Smith 2002 [pro phylum Foraminifera] Class ASTRORHIZATA Saidova 1981; emend. Mikhalevich 1995 Subclass ASTRORHIZANA Saidova 1981 Order ASTRORHIZIDA Lankester 1885 [nom. correct. Calkins 1909 pro order Astrorhizidea Lankester 1885; = Astrorhizida Fursenko 1958] Suborder ASTRORHIZINA Lankester 1885 Family HIPPOCREPINELLIDAE Loeblich and Tappan 1984; emend. Mikhalevich 1995 Genus Amphitremoida Eisenack 1938; emend. Nestell and Tolmacheva 2004 [= Croneisella Dunn 1942; = Pachyammina Eisenack 1967; = Quasibeothuka Wang in Wang et al. 2008] Type species: Amphitremoida citroniforma Eisenack 1938. Amphitremoida simehkuhensis Nestell and Ghobadi Pour, n. sp.

Plate 1, figures 1-2 Description: Test is free, monothalamous, elongate fusiform in shape, with slightly extended and truncated poles. These pole areas have two apertures, one at each end. One aperture is smaller than the other one. The width of the smaller aperture is 110 µm; the width of thicker one is 120 µm. The apertures are


TEXT-FIGURE 3 Backscattered electron images and energy-dispersive X-ray spectrum from the selected area (black dot) of Psammosphaera rugosa Eisenack. A, the spectrum of grains, probably of feldspar degradation; B and D, the spectrum of the feldspar grain; C, the spectrum of the brownish patch (white color area herein) with the high peaks of iron and silica.

completely plugged because of the type of preservation. The wall is agglutinated, consisting of fine-grained quartz; color is brownish with white patches. Dimensions in µm: test length (L) 1200, width (W) 480-580, form ratio L/W 2.1-2.5; in holotype correspondingly 1200, 480, 2.5.

Designation of types: The specimen illustrated on plate 1, figure 2 is designated as the holotype (no. AEU/L5502) and specimen on plate 1, figure 1 (no. AEU/L5501) as the paratype; Iran, Alborz Mountains, city of Damghan; Simeh-Kuh section, Lashkarak Formation; Middle Ordovician, Darriwilian, Eoplacognathus? pseudoplanus conodont Zone.

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Etymology: After the Simeh-Kuh section, near the city of Damghan, Alborz Mountains, northern Iran.

250-300, thickness with rim 210-240, the height of the test without base 180, with base 200.

Material: Two specimens from sample C-10.

Designation of types: The specimen illustrated on plate 1, figure 4c is designated as the holotype (no. AEU/L5504) and specimens on plate 1, figure 4d (left specimen no. AEU/L5505, right specimen –no. AEU/L5506) as the paratypes; Iran, Alborz Mountains, city of Damghan; Simeh-Kuh section, Lashkarak Formation; Middle Ordovician, Darriwilian, Eoplacognathus? pseudoplanus conodont Zone.

Discussion: Based on the elongate fusiform shape of the test, the new species A. simehkuhensis is similar to A. longa Nestell and Tolmacheva (2004, p. 264, pl. 4, figs. 1-3) from the Lower Ordovician (Floian, Latorp Regional Stage) of northwestern Russia, and A. sp. 1 from the Middle Ordovician (Darriwilian) of Argentina (Nestell et al. 2009). From A. longa the new species differs by slight concavity of the prepolar regions of the test, larger test size, different form ratio and younger stratigraphic interval. From Amphitremoida sp. 1, the new species differs by a thicker central part and less elongate test, and smaller form ratio. Occurrence: The same as the holotype and paratype.

Etymology: After the Lashkarak Formation, Simeh-Kuh section, Alborz Mountains, northern Iran. Material: Three specimens from sample C-10. Discussion: See discussion in the description of the genus. Occurrence: The same as the holotype and paratype.

Suborder SACCAMMININA Lankester 1885 Family STEGNAMMINIDAE Moreman 1930 [nom. transl. Mikhalevich 1995 ex subfamily Stegnammininae Moreman 1930] Subfamily HEMISPHAERAMMININAE Loeblich and Tappan 1961; emend. Vdovenko et al. 1993; emend. Mikhalevich 1995 Genus Damghanites Nestell and Ghobadi Pour, n. gen.

Superfamily PSAMMOSPHAEROIDEA Haeckel 1894 Family PSAMMOSPHAERIDAE Haeckel 1894 Subfamily PSAMMOSPHAERINAE Haeckel 1894 Genus Psammosphaera Schulze 1875 Type species: Psammosphaera fusca Schulze 1875. Psammosphaera rugosa Eisenack 1954

Plate 1, figures 5–9; Text-figure 3 Type species: Damghanites lashkarakensis Nestell and Ghobadi Pour, n. sp. Description: Test attached, monothalamous, oval in top view, and helmet shaped in side view with slight rim just above the site of the small wide basal cylindrical shaped attachment. There is no aperture, and pores were not observed. Wall is agglutinated, white in color, composed of different size quartz grains. Etymology: After the city of Damghan, Alborz Mountains, northern Iran. Composition of the genus: monotypic. Discussion: Based on the small wide basal cylindrical shaped attachment and helmet shaped test, the new genus is different from all known attached monothalamous foraminifers without apertures. Range: Middle Ordovician, Darriwilian Stage, Eoplacognathus? pseudoplanus conodont Zone. Damghanites lashkarakensis Nestell and Ghobadi Pour, n. sp.

Plate 1, figure 4 Description: Test attached, monothalamous, oval in top view, and helmet shaped in side view with slight rim just above the site of the small wide basal cylindrical shaped attachment. The height of the attachment is 26–30 µm, the width 170–200 µm. Aperture and pores were not observed, but it is possible that very fine pores are present between quartz grains, but could not be seen even under high magnification in Scanning Electron Microscope (Pl. 1, fig. 4f). Wall is agglutinated, white in color, composed of different size quartz grains ranging from 2 to 15 µm. Some scattered large grains of feldspar are present in the wall (Pl. 1, fig. 4e). Dimensions in µm: the test width is

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Description: Test is free, large, spherical or close to spherical shape, with a rough surface. Wall is agglutinated, white in color with brownish patches which indicate oxidation (text-fig. 3C), and consists of fine quartz grains, with inclusion of rare large feldspar grains (text-fig. 3B, D) protruded in some places (Pl. 1, fig. 7) and probably of small grains of products of feldspar degradation (text-fig. 3A). The diameter of the tests is 350-600 µm. Material: Abundant in sample C-10 and two tests from sample C-9. Discussion: The sizes and rough wall of our specimens are similar to the type specimens of Psammosphaera rugosa described by Eisenack (1954) from the Ordovician, Stage D 3 , Vasalemma Formation of Estonia, which at the present day is assigned to the Late Ordovician, Katian (Oandu Regional stage) (Kröger et al. 2014). In the description of the new species Eisenack pointed out that this species has a very characteristic wall which consists of “relatively coarse quartz grains irregularly protruding over the surface in some places” (Eisenack 1954, p. 58). We consider that these protruded “coarse quartz grains” are grains of feldspar as shown in text-figure 3B and 3D. Occurrence: Middle Ordovician, Darriwilian, Lashkarak Formation, northern Iran; Upper Ordovician, Katian, Vasalemma Formation of Estonia.

Genus Sorosphaera Brady 1879; emend. Kristan-Tollmann 1971 Type species: Sorosphaera confusa Brady 1879. Sorosphaera iranensis Nestell and Ghobadi Pour, n. sp.

Plate 1, figures 10-11


TEXT-FIGURE 4 Backscattered electron images and energy-dispersive X-ray spectrum from the selected area (black dot) of Sorosphaera darriwiliensis Nestell and Ghobadi Pour, n. sp. A, the spectrum of a feldspar grain; B, the spectrum of the brownish patch (white color area herein) with the high peaks of iron rich area.

Description: Test is free, pseudocolonial (pseudo-multichambered), consists of spherical or subspherical chambers attached to each other in a generally linear manner, in some cases biserially. The number of chambers is 9–11. Chambers are relatively large with diameter 200–230 µm. Aperture and pores were not observed. Wall is agglutinated, white in color with brownish patches, which indicates oxidation, and consists of fine quartz grains ranging from 5 to 14µm, sometimes with the inclusions of rare large feldspar grains (Pl. 1, fig. 11b).

Dimensions in µm: the length of the pseudocolony is 1200– 1240, width 300–370. Designation of types: The specimen illustrated on plate 1, figure 11a is designated as the holotype (no. AEU/L5513); Iran, Alborz Mountains, city of Damghan; Simeh-Kuh section, Lashkarak Formation; Middle Ordovician, Darriwilian, Eoplacognathus? pseudoplanus conodont Zone.

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Etymology: After the country of Iran.

Material: Five specimens from sample C-10.

Material: Two specimens from sample C-10.

Discussion: Based on the number and character of adjoining chambers, the described specimens are similar to the tests of the species Sorosphaera tricella described by Moreman (1930, p. 49, pl. 5, figs. 12, 14) from the Silurian of the Arbuckle Mountains in Oklahoma, USA. But, our specimens differ from S. tricella by their hemispherical chambers, not spherical chambers as in S. tricella. Kristan-Tollmann (1971) revised the genus Sorosphaera and proposed to include within the scope of the genus only forms with spherical chambers, and forms with hemispherical and attached chambers were assigned to the genus Webbinelloidea Stewart and Lampe 1947. On one hand, our specimens possess free tests that are characteristic for the genus Sorosphaera; on the other hand, their chambers are hemispherical in shape, which is characteristic for the genus Webbinelloidea. At the present time, we cannot solve the generic affiliation of our specimens because the hemispherical shape of chambers can be result of possible compression of the test. So, we assign the specimens to the genus Sorosphaera conditionally.

Discussion: Based on the spherical and subspherical shape of the chambers, the new species is similar to the species described as Sorosphaera confusa Brady by Mound (1961, p. 33, pl. 3, figs. 1–3) and McClellan (1966, p. 471, pl. 37, fig. 6, pl. 41, fig. 6) from the Silurian of southeastern Indiana, USA, but differs from it by the growth of the chambers in the linear manner and larger size of the chambers. Occurrence: The same as the holotype. Sorosphaera darriwiliensis Nestell and Ghobadi Pour, n. sp.

Plate 1, figures 12-13; Text-figure 4 Description: Test is free, pseudocolonial, consists of cluster of spherical chambers irregularly arranged. The number of chambers is 5–6. Chambers are joined in loose manner or sometimes touch each other. The diameter of an individual is 200–400 µm. The wall is agglutinated, white in color with brownish patches which indicate oxidation (text-fig. 4B), and consists of small quartz grains, with inclusion of rare large feldspar grains up to 45 µm (text-fig. 4A), and probably of small grains of products of feldspar degradation. The length of the pseudocolony is 750–1100 µm. Designation of types: The specimen illustrated on plate 1, figure 12 is designated as the holotype (no. AEU/L5514) and specimens on plate 1, figure 13 (no. AEU/L5515) as the paratype; Iran, Alborz Mountains, city of Damghan; Simeh-Kuh section, Lashkarak Formation; Middle Ordovician, Darriwilian, Eoplacognathus? pseudoplanus conodont Zone. Etymology: After the occurrence in the Darriwilian Stage of the Middle Ordovician of Iran. Material: Two specimens from sample C-10. Discussion: Based on many chambers gathered in a cluster, the new species is similar to Sorosphaera subconfusa Dunn (1942, p. 325, pl. 42, figs. 16, 20) from the Silurian Osgood Limestone of Missouri, USA and Sorosphaera papilla Gutschick and Treckman (1959, p. 232, pl. 33, figs. 8–13) from the Mississippian, Kinderhookian Rockford Limestone of northern Indiana, USA. From S. subconfusa, the new species S. darriwiliensis differs by loosely arranged chambers and larger size of the individual chambers; and from S. papilla the new species differs by also loosely attached chambers and larger size of the individual chambers, and the absence of papilla on the surface of the chambers. Occurrence: The same as the holotype and paratype. Sorosphaera? sp. aff. S. tricella Moreman 1930

Plate 1, figure 14; Text-figure 5 Description: Test is free, pseudocolonial, consists of two-three hemispherical chambers joined together. The diameter of an individual is 300–400 µm. The wall is agglutinated, white in color with brownish patches which indicate oxidation (text-fig. 5A), and consists of small quartz grains (text-fig. 5D, E), with inclusions of rare reddish-brown anatase (text-fig. 5B, C) and rare calcite grains. The length of a pseudocolony with three chambers is 730 µm.

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Occurrence: Middle Ordovician, Darriwilian; Simeh-Kuh section, Lashkarak Formation, Eoplacognathus? pseudoplanus conodont Zone; city of Damghan, Alborz Mountains, northern Iran. CONCLUSIONS

The study of Middle Ordovician (Darriwilian) strata from the Alborz Mountains in northern Iran shows that they contain monothalamous agglutinated foraminifers. These foraminifers are described for the first time from two levels of the Lashkarak Formation. One new genus Damghanites Nestell and Ghobadi Pour with the type species D. lashkarakensis, and three new species Amphitremoida simehkuhensis, Sorosphaera iranensis and S. darriwiliensis have been described. Using energy-dispersive X-ray and Raman spectroscopy analyses allowed the identification of the composition of the test wall of these agglutinated foraminifers. Their walls consist of fine quartz grains with the inclusion of feldspar grains, products of feldspar degradation, and very rare grains of anatase, and also iron, which indicate oxidation. The foraminifers occur together with ostracods, brachiopods, trilobites and conodonts. Occurrence of conodonts Microzarkodina hagetiana and Baltoniodus cf. B. norrlandicus in the lower part of the Lashkarak Formation allow the correlation with the lower part of the Kunda Regional Stage (Lenodus variabilis Biozone) of Baltoscandia (early Darriwilian). Stratigraphically younger sample C-10 yielding diverse foraminifers can be dated by conodont species Eoplacognathus? pseudoplanus (Viira 1974) indicating correlation with the Eoplacognathus? pseudoplanus Zone of the upper part of the Kunda Regional Stage of Baltoscandia. ACKNOWLEDGMENTS

We are grateful to Mike Kaminski for a very careful constructive review, which was very helpful in improving the manuscript. Leonid Popov and Mansoureh Ghobadi Pour acknowledge logistical support from the National Museum of Wales. Research in Iran by Mansoureh Ghobadi Pour was supported by Golestan University. We are grateful to Vachik Hairapetian


TEXT-FIGURE 5 A, the image of Sorosphaera? aff. S. tricella Moreman, x 10, no. AEU/L5534, taken with a DXRTMxi Raman imaging microscope, scale bar 500 µm; B, the location of the anatase grain, x 50, scale bar 20 µm; C, the spectrum of anatase crystal shown in the circle in (B); D, the quartz grain in the red circle, x 50, scale bar 20 µm; E, the spectrum of the quartz grain. Red lines represent spectrum of the anatase and Quartz in the RRUFF Raman Library, blue lines are spectra of anatase and quartz grains in the wall of foraminifera.

(Azad University, Esfahan) for the assistance in fieldwork and chemical preparation of the specimens. We thank Merlynd Nestell (University of Texas at Arlington) for discussions about foraminiferal classification and also checking the English.

EICHWALD, C. E. von, 1830. Zoologia specialis, vol. 2. Vilnae, D. E. Eichwaldus, 323 pp. EISENACK, A., 1938. Neue Mikrofossilien des baltischen Silurs. Paläeontologische Zeitschrift, 19 (3–4): 217–243.

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GHOBADI POUR, M., POPOV, L. E., KEBRIAEE-ZADEH, M. R. and BAARS, C., 2011. Middle Ordovician (Darriwilian) brachiopods associated with the Neseuretus biofacies, eastern Alborz Mountains, Iran. Memoirs of the Association of Australasian Palaeontologists, 42: 263–283.

———, 2002. The phagotrophic origin of eukaryotes and phylogenetic classification of Protozoa. International journal of Systematic and Evolutionary Microbiology, 52: 297–354. DESMAREST, A. G., 1817. Crustacés Fossiles. Nouveau Dictionnaire d’Histoire Naturelle, 8: 495–519. DUNN, P. H., 1942. Silurian Foraminifera of the Mississippi Basin. Journal of Paleontology, 16 (3): 317–342.

GHOBADI POUR, M., WILLIAMS, M., VANNIER, J. M. C., MEIDLA, T. and POPOV, L. E., 2006. Ordovician ostracods from east central Iran. Acta Palaeontologica Polonica, 51: 551–560. GHOBADI POUR, M., WILLIAMS, M. and POPOV, L. E., 2007. A new Middle Ordovician arthropod fauna (Trilobita, Ostracoda, Bradoriida) from the Lashkarak Formation, Eastern Alborz Mountains, northern Iran. GFF, 129: 245–254.

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PLATE 1 Middle Ordovician (Darriwilian) foraminifers from the Simeh-Kuh section, Lashkarak Formation, sample C-10 except fig. 9 (sample C-9). Scale bar – 100 µm except 4e, 4f, 5b, 11b – 10 µm; 7 – 180 µm; 9 - 160 µm; 13 - 290 µm. 1-2 Amphitremoida simehkuhensis Nestell and Ghobadi Pour, n. sp. 1 – no. AEU/L5501, paratype; 2 – no. AEU/L5502, holotype. 3 Amphitremoida sp. aff. A. longa Nestell and Tolmacheva 2004, no. AEU/L5503. 4a-f Damghanites lashkarakensis Nestell and Ghobadi Pour, n. gen., n. sp. 4a – three tests attached to sponge spicules, test in the middle is the holotype (no. AEU/L5504), two others (left specimen – no. AEU/L5505 and right specimen – no. AEU/L5506 from the holotype) – paratypes; 4b – view of 1a tilted o onto 30 ; 4c – enlarged view of the holotype; 4d – enlarged view of the paratype (left test on fig. 4a); 4e – enlarged view of the 4d showing a large feldspar grain attached to the test wall consisting of quartz grains; 4f – enlarged view of the test wall showing different size of quartz grains.

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5-9 Psammosphaera rugosa Eisenack 1954. 5 – no. AEU/L5507, 5b – enlarged view of the test wall; 6 – no. AEU/L5508; 7 – no. AEU/L5509, 8 – no. AEU/L5510; 9 – no. AEU/L5511. 10-11a,b Sorosphaera iranensis Nestell and Ghobadi Pour, n. sp. 10 – no. AEU/L5512, linear aggregate of monothalamous tests; 11a – no. AEU/L5513, holotype, pseudocolony of the globular chambers attached to each other in a linear manner, 11b – enlarged view of the test wall with large feldspar grain. 12-13 Sorosphaera darriwiliensis Nestell and Ghobadi Pour, n. sp., clusters of spherical chambers. 12 – no. AEU/L5514, holotype, 13 – no. AEU/L5515, paratype. 14 Sorosphaera? sp. aff. S. tricella Moreman 1930, no. AEU/L5516, small pseudocolony consisting of three hemispherical chambers.

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MOREMAN, W. L., 1930. Arenaceous Foraminifera from Ordovician and Silurian limestones of Oklahoma. Journal of Paleontology, 4: 42–59. MOUND, M. C., 1961. Arenaceous Foraminifera from the Brassfield Limestone (Albion) of southeastern Indiana. Indiana Department of Conservation, Geological Survey Bulletin, 23: 1–38. NESTELL, G. P. and TOLMACHEVA, T. Yu., 2004. Early Ordovician foraminifers from the Lava Section, northwestern Russia. Micropaleontology, 50: 253–280. NESTELL, G. P., HEREDIA, S., MESTRE, A., BERESI, M. and GONZÁLEZ, M., 2011. The oldest Ordovician foraminifers (Oepikodus evae conodont Zone, Floian) from South America. Geobios, 44: 601–608. NESTELL, G. P., MESTRE, A. and HEREDIA, S., 2009. First Ordovician Foraminifera from South America: a Darriwilian (Middle Ordovician) fauna from the San Juan Formation, Argentina. Micropaleontology, 55: 329–344. ORBIGNY, A. d’, 1826. Tableau méthodique de la classe des Céphalopodes. Annales des Sciences Naturelles, 7: 245–314. OWEN, R., 1858. Palaeontology. Encyclopedia Britannica (8th edition). Traill, T.S., Ed., Edinburgh, 17: 91–176. PANDER, C. H., 1856. Monographie der fossilen Fische des Silurischen Systems der Russisch-Baltischen Gouvernements. St. Petersburg, Akademie der Wissenschaften, 91 pp. POPOV, L. E., GHOBADI POUR, M. and HOSSEINI, M., 2008. Early to Middle Ordovician lingulate brachiopods from the Lashkarak Formation, Eastern Alborz Mountains, Iran. Alcheringa, 32: 1–35. POPOV, L. E., KEBRIAEE-ZADEH, M. R. and GHOBADI POUR, M., 2016. Emergence of the Saucrorthis Fauna in the Middle Ordovician of northern Iran. Australasian Palaeontological Memoirs, 49: 485–514.

SAIDOVA, Kh. M., 1981. O sovremennom sostoyanii sistemy nadvidovykh taksonov kaynozoyskikh bentosnykh foraminifer [On an up-to-date system of supraspecific taxonomy of Cenozoic benthonic foraminifers]. Nauka, Moscow, 72 pp. (In Russian) SCHULTZE, F. E., 1875. Zoologische Ergebnisse der Nord-seefahrt, vom 21 Juli bis 9 September, 1872. I, Rhizopoden. II, Jahresberichte Kommission zur Untersuchung der Deutschen Meer in Kiel für die Jahr 1872, 1873: 99–114. SERGEEVA, S. P., 1963. Conodonts from the Lower Ordovician of the Leningrad region. Paleontologicheskiy Zhurnal, 2: 93–108. (In Russian) ———, 1974. Some new Ordovician conodonts from the Leningrad region. Paleontologicheskiy Sbornik, 11: 79–84. (In Russian) STEWART, G. A. and LAMPE, L., 1947. Foraminifera from the Middle Devonian Bone Beds of Ohio. Journal of Paleontology, 21: 529–536. STOUGE, S. and BAGNOLI, G., 1990. Lower Ordovician (Volkhovian-Kundan) conodonts from Hagudden, northern Öland, Sweden. Palaeontologica Italiana, 77: 1–54. VDOVENKO, M. V., RAUSER-CHERNOUSSOVA, D. M., REITLINGER, E. A. and SABIROV A. A., 1993. Reference book on the systematics of Paleozoic smaller Foraminifera. Moscow, Nauka, 126 pp. (In Russian) VIIRA, V., 1974. Ordovician conodonts of the East Baltic. Eesti NSV Teaduste Akadeemia Geoloogia Instituudi, Tallin, 142 pp. (In Russian) WANG, Y., CHENG, J. and ZHANG, Y., 2008. New radiolarian genera and species of Teituao Formation (Ordovician) in the Kuruktag region, Xinjiang. Acta Palaeontologica Sinica, 47(4): 393–404. [In Chinese with English summary]

PLATE 2 Middle Ordovician (Darriwilian) conodonts from the Simeh-Kuh section, Lashkarak Formation. Scale bar –100 µm. 1-3 Microzarkodina hagetiana Stouge and Bagnoli 1990. 1 - no. AEU/L5517, P element, lateral view, sample C-9/1-2; 2 - no. AEU/L5518, P element, lateral view, sample C-9/1-2; 3 - no. AEU/L5519, M element, lateral view, sample C-9/1. 4,6,7,9 Baltoniodus cf. B. norrlandicus (Löfgren 1978). 4 no. AEU/L5520, Pa element, upper view, sample C-10; 6 - no. AEU/L5521, Sd element, lateral view, sample C-10; 7 - no. AEU/L5522, Pb element, lower view, sample C-10; 9 - no. AEU/L5523, Sc element, lateral view, sample C-10. 5 Eoplacognathus? pseudoplanus (Viira 1974), no. AEU/L5524, dextral Pb element, inner lateral view, sample C-10. 8 Baltoniodus sp., no. AEU/L5525, Pb element, lateral view, sample C-9/1-2.

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10,14,15 Periodon sp. 10 - no. AEU/L5526, M element, lateral view, sample C-10; 14 – no. AEU/L5527, Sc element, lateral view, sample C-10; 15 - no. AEU/L5528, Sb element, lateral view, sample C-9/1-2. 11 Drepanodus arcuatus Pander 1856, no. AEU/L5529, Sc element, lateral view, sample C-10. 12 Venoistodus cf. V. balticus Löfgren 2006, no. AEU/L5530, M element, inner lateral view, sample C-10. 13 Scalpellodus gracilis (Sergeeva 1974), no. AEU/L5531, P element, lateral view, sample C-10. 16-17 Genus et species indet. 16 - no. AEU/L5532, Sd element, a - lateral view, b - posterior view, sample C-10; 17 - no. AEU/L5533, ?Sb element, lateral view, sample C-10.

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