ABSTRACT

Thirty-three brachiopod species from the Guadalupian Ruteh Limestone of North Iran are here systematically described and illustrated. Brachiopods have been collected bed-by-bed along five stratigraphic sections and in one fossiliferous locality in the region between Dorud and Shirinibad in the Alborz Mountains. Four new species and one new genus are erected in the present paper: Haydenella eminens n. sp. Perigeyerella rutehiana n. sp., Martinia bassa n. sp. and Bisolcatelasma iraniana n. gen. n. sp.

Quantitative biostratigraphic analysis of the brachiopod data based on the Unitary Association method (Guex, 1991) has lead to the construction of a local sequence of three discrete biozones: the Squamularia sp. B-M. bassa Biozone at the base of the formation, the H. kiangsiensis-N. (N.) asseretoi Biozone in its middle part and the R. exile-R. gemmellaroi Biozone at its top. The latter however has been recognized only in the Shirinabad section.

As already envisaged for the Carboniferous and Lower Permian brachiopod faunas from North Iran, the Guadalupian fauna is comprised mostly of cosmopolitan taxa, confirming the role of the Iranian microplate as a staging-post for most of the late Palaeozoic. When compared to the younger Lopingian faunas collected in the same regions of North Iran, the Ruteh brachiopods appear significantly different, indicating a marked biotic change in the brachiopod communities across the end-Guadalupian biotic crisis.

INTRODUCTION

The aim of this paper is to systematically describe the brachiopod fauna of the Ruteh Limestone collected bed-by-bed along several stratigraphic sections in the Alborz mountain chain and to discuss their biostratigraphic implications. This study increases the knowledge of Guadalupian brachiopods from the Cimmerian blocks, which are important in understanding the complex pattern of the opening of the Neo-Tethys Ocean (Muttoni et al., 2009a, b). This allows a preliminary comment on the palaeobiogeographic affinity of the Ruteh brachiopods to be reported herein.

The study of Guadalupian brachiopod distribution is also important for unraveling the pattern of the end-Guadalupian biotic crisis (i.e. Jin et al., 1994; Clapham et al., 2009; Isozaki and Aljinovich, 2009; Shen and Shi, 2009). The biotic crisis deeply affected several fossil groups, including fusulinids, bivalves, corals and brachiopods, and its causes are still not clear.

This paper completes the revision and description of the Upper Palaeozoic brachiopod associations of North Iran, starting with the Cisuralian faunas (Angiolini and Stephenson, 2008) and continuing with the Lopingian (Angiolini and Carabelli, 2010) and Mississippian ones (Bahrammanesh et al., 2011). These systematic descriptions update the palaeontological works done in the sixties by Gaetani (1964, 1965, 1968), Fantini Sestini (1965a, b, c) and Fantini Sestini and Glaus (1966), which were based on smaller collections and provide a survey of the faunal succession and biotic events which characterized the Iranian microplate from the base of the Carboniferous to the Permian–Triassic event.

GEOLOGICAL SETTING

The brachiopods described in the present paper have been collected in the Alborz mountain range in North Iran, a 1,500 km long mountain system, flanking to the south of the Caspian Sea (Figure 1). The Alborz range is a seismically active belt resulting from Late Tertiary–Quaternary intracontinental transpression and structured above an ancient Eo-Cimmerian collisional orogen, which is still recorded at its core (Zanchi et al., 2006). The Palaeozoic–Mesozoic stratigraphic succession preserved in the Alborz (Assereto, 1966) was deposited along the passive margin of the Iranian microplate, which detached from the Gondwanan margin in the Early Permian and drifted northward to collide with the Eurasian margin in the Late Triassic (Muttoni et al., 2009a, b; Gaetani et al., 2009; Zanchi et al., 2009).

The Pennsylvanian–Upper Permian succession of the Alborz mountain range has been recently revised by Gaetani et al. (2009); it starts with the Pennsylvanian–Sakmarian Dorud Group, which is unconformably capped by the Ruteh Limestone, a thick carbonate platform of Middle Permian age, from which the brachiopods described in the present paper have been sampled. The Ruteh Limestone is in turn overlain by a lateritic horizon with karst features indicating prolonged subaerial exposure under tropical climate conditions (Muttoni et al., 2009b). During the Late Permian the succession is transgressed by the marine limestone and marlstone of the Nesen Formation.

The Ruteh Limestone was established by Assereto (1963), with its type-section designated north of Ruteh in the Jaj Valley. Gaetani et al. (2009) revised its upper boundary placing it at the base of the lateritic horizon, which corresponds to Assereto’s upper ironstone (1963, p. 537, fig. 11). The Ruteh Limestone is generally 150–250 m-thick reaching 600 metres along the Caspian side of the Alborz; it comprises dark grey marly bioclastic packstone at the base, followed by a succession of well-bedded bioclastic packstone and wackestone with local intercalations of marlstone and black cherty nodules and frequent Zoophycos trace fossils. Basaltic lava flows and tuffs occur in the upper part of the Ruteh Limestone in the area north of Elikah-Nesen (Gaetani et al., 2009).

Brachiopods have been collected bed-by-bed along five stratigraphic sections: Dorud (36°00′18.3″N, 51°29′01.6″E), Ruteh (35°58′38.3″N, 51°32′28.9″E) and Ruteh Valley (35°58′35.2″N, 51°31′59.0″E), Mangol Restaurant 1 (36°14′58.2″N, 52°22′05.1″E), and Shirinabad (36°53′46″N, 55°09′30″E) (Figures 27) and in the fossiliferous locality of Khouban Pass (Figure 1; Table 1), where a section could not be measured due to the poor quality of the outcrop.

THE BRACHIOPOD FAUNA

The brachiopod fauna described in this study is based on 455 specimens and is comprised of 33 species belonging to 27 genera of which four species and one genus are new: Neochonetes (Nongtaia) asseretoi (Fantini Sestini, 1964), Haydenella kiangsiensis (Kayser, 1883), Haydenella aff. H. khasorensis (Reed, 1944), Haydenella eminens n. sp., Ogbinia sp. ind., ?Entacanthadus sp. ind., ?Otariella sp. ind., Spinomarginifera sp. ind., Tyloplecta cf. T. yangtzeensis (Chao, 1927), Reticulatia sp. ind., Bilotina yanagidaiAngiolini and Bucher, 1999, Vediproductus vediensis Sarytcheva, 1965, Linoproductus aff. L. lineatus (Waagen, 1884), ?Linoproductus sp. ind., Magniplicatina sp. ind., ?Chonostegoides sp. ind., ?Urushtenoidea sp. ind., Orthothetina vediensis Sokolskaya, 1965, Orthothetina sp. ind., Perigeyerella rutehiana n. sp., Schuchertella semiplana (Waagen, 1883), Kotlaia bistriata (Reed, 1944), ?Spirigerella sp. ind., Martinia bassa n. sp., Squamularia sp. A, Squamularia sp. B, ?Permophricodothyris sp. ind., Reticulariina sp. ind., Rostranteris exileGemmellaro, 1899, Rostranteris gemmellaroiSmirnova and Grunt, 2002, Dielasma sp. ind., Omanilasma aff. O. husseinii Angiolini and Zarbo, 2006 and Bisolcatelasma iraniana n. sp.

The brachiopod fauna of the lower and middle part of the Ruteh Limestone was previously known through the works of Fantini Sestini (1965b) who described 41 species from eleven fossiliferous beds in the area between Hasanakdar and Ruteh (Table 2), so more to the west than the outcrops we studied (Figure 1). The assemblages described by Fantini Sestini (1965b) as having been collected at Khouban Pass and at Ruteh correspond to some of the beds collected by us in the same localities. The material described by Fantini Sestini (1965b) generally consists of very few specimens for each taxon, some of which are poorly preserved; however notable is her record of species of the genera Cleiothyridina, Meekella and Whitspakia, which we were not able to find again in the field, and also of three specimens of Orbicoelia sp. ind. (determined by Fantini Sestini as Crurithyris tschernyschewiLicharew, 1939).

To test the biotic affinity of the brachiopod assemblages from the Ruteh Limestone a preliminary comparison has been made with coeval peri-Gondwanan faunas and Palaeotethyan ones. A further aim is to perform a detailed palaeobiogeographic analysis from the Gondwanan margin to the Cimmerian blocks in a following paper. The brachiopod assemblages described in the present paper are more similar to the Guadalupian peri-Gondwanan faunas of southeastern Oman (Angiolini and Bucher, 1999; Angiolini et al., 2003, 2004), Turkey (Verna et al., 2011) and the Salt Range (Waagen, 1882–1885) than to those from the Cimmerian blocks of Central Afghanistan (Termier et al., 1974), Karakorum (Angiolini, 1996, 2001), Tunisia (Verna et al., 2010) and Sosio (Gemmellaro, 1899) in the Tethyan Gulf. This peri-Gondwanan affinity is due to the palaeogeographic position of the Iranian microplate in the Guadalupian, which, according to Muttoni et al. (2009b), was still close to the Gondwanan margin due to the differential opening of the Neo-Tethys Ocean. Muttoni et al. (2009b) inferred lower seafloor spreading rates for Iran than for the Cimmerian terranes of Central Afghanistan, western Karakorum, and Qiangtang and a narrow ocean between Iran and Turkey-Oman.

As already envisaged for the Carboniferous and Lower Permian brachiopod faunas from North Iran (Angiolini and Stephenson, 2008; Bahrammanesh et al., 2011), the Guadalupian fauna is also mostly comprised of cosmopolitan taxa, with only one endemic genus and a few endemic species. This confirms the role of the Iranian microplate as a staging-post for most of the late Palaeozoic.

As stated above, the distribution of Guadalupian brachiopods is very important to understand the pattern of the end-Guadalupian biotic crisis. However, the Ruteh Limestone records the occurrence of brachiopods mostly at its base and in its middle part, as shown by the distribution of our collections (Figures 27) and by the work of Fantini Sestini (1965b). Brachiopods from the top of the Ruteh Limestone have been collected only along the Shirinabad section (Figure 6) and constitute a distinctive association (see paragraphs below). Furthermore the top of the Ruteh Limestone always shows evidence of subaerial exposure related to the occurrence of a major sea-level drop at the Guadalupian/Lopingian boundary (e.g. Haq and Shutter, 2008). So we have no direct evidence on how the end-Guadalupian crisis affected the North Iran brachiopod assemblages. Comparing the taxonomic composition of the brachiopods of the Ruteh Limestone with those of the overlying Nesen Formation (Angiolini and Carabelli, 2010) it is evident that only two species (T. yangtzeensis and S. semiplana) and five genera (Neochonetes, Spinomarginifera, Haydenella, Squamularia and Permophricodothyris) range upward in the Lopingian, indicating a significant biotic change in the brachiopod communities of North Iran across the end-Guadalupian biotic crisis.

QUANTITATIVE BIOSTRATIGRAPHY

Among the different methods of quantitative biostratigraphy, the Unitary Association (UA) method of Guex (1991) and Savary and Guex (1991) is the one that it is better suited for the biostratigraphic classification of Palaeozoic brachiopods (Angiolini and Bucher, 1999), which have a discontinuous record through the successions. The UA method is a deterministic mathematic method to construct biozones, seeking for coexistence or superimposition relationships among species to define maximal associations of coexistent species which are named unitary associations. This method considers also virtual coexistences, which have not been observed directly along the stratigraphic sections, but that are potentially possible. The result of the analysis is a discrete sequence of intervals of coexisting species, with each interval characterized by a group or a couple of species (Guex, 1991). The lateral reproducibility of the reconstructed associations gives them a chronological significance and allows long-distance correlation. The quantitative biostratigraphic analysis has been performed using the PAST Program (Hammer et al., 2001), based on a data-set containing 33 species from five sections/fossiliferous localities: Khouban Pass (Table 1), Dorud (Figure 2), Ruteh (Figure 3), Mangol Restaurant 1 (Figure 4) and Shirinabad (Figures 5, 6).

The Ruteh Valley section (Figure 7) has not been included in the analysis as it records only a single occurrence of the common species O. aff. O. husseinii, which occurs in most of the assemblages.

At first all the available data have been processed in a single run. However, this run yielded conflicting results and a very low lateral reproducibility of the sorted UAs. As the brachiopod record along the measured sections is very discontinuous and fossiliferous beds occur only in the lower and middle parts of the formation, but not in the intervening succession, two distinct analyses have been performed. A first one relates to the basal part of the formation and it is based on the fossil assemblages from the Khouban Pass, Dorud, and Ruteh sections; the second one concerns the middle to upper part of the Ruteh Limestone sampled at the Mangol Restaurant 1 and Shirinabad sections.

The first of these two separate runs (Figure 8) yields two UAs, with good superpositional control, lateral reproducibility and a minimum number of contradictions and they are characterized by the following species:

UA1: Reticulariina sp. ind.;

UA2: ?Permophricodothyris sp. ind., ?Spirigerella sp. ind. and Squamularia sp. B.

In comparison UA1 has a low lateral reproducibility, a low diversity and is strictly defined only in bed IR60, whereas UA2 allows the correlation between the two sections and the fossiliferous locality of Khouban Pass (Figure 8, 10). UA1 can be merged with UA2 with which it shares the species M. bassa n. sp., P. rutehiana n. sp. and Squamularia sp. B, forming a biozone which is correlatable in the three sections. This is named the Squamularia sp. B-M. bassa Biozone and it is based on the occurrence of the index species and/or Reticulariina sp. ind., ?Permophricodothyris sp. ind., ?Spirigerella sp. ind. and Squamularia sp. B.

The second run, based on the assemblages collected in the middle-upper part of the Ruteh Limestone, yields eight UAs (Figure 9) that are characterized by the following species:

UA1: ?Chonostegoides sp. ind.;

UA2: Ogbinia sp. ind.;

UA3: O. vediensis;

UA4: ?Urushtenoidea sp. ind.;

UA5: the couple of species T. cf. T. yangtzeensis and Dielasma sp. ind.;

UA6: H. aff. H. khasorensis, K. bistriata, L. aff. L. lineatus, Orthothetina sp. ind., Spinomarginifera sp. ind.

and V. vediensis;

UA7: B. iraniana n. gen. n. sp. and Magniplicatina sp. ind.;

UA8: ?Entacanthadus sp. ind., ?Otariella sp. ind., R. exile and R. gemmellaroi.

UAs 1–5 and UAs 7–8 have been only identified in the Shirinabad section, whereas UA6 allows the correlation of the two sections (Figure 10). UAs 1–5 occur along a thickness of 5.2 metres only and have several species in common with UA6: H. kiangsiensis, N. (N.) asseretoi, P. rutehiana n. sp. and Squamularia sp. A. UA7 on the other hand has been strictly identified only in bed IR649 which is 2.7 metres above UA6 and except for the first occurrence of B. iraniana n. gen. n. sp. and Magniplicatina sp. ind. represents an impoverished association of UA6. So we propose to merge UA1 to UA7 and identify a biozone named H. kiangsiensis-N. (N.) asseretoi Biozone, characterized by the index species and those that characterize the UAs 1 to 7. UA8 occurs just below the top of the Ruteh Limestone in the Shirinabad section and represents a distinctive biozone, named R. exile-R. gemmellaroi Biozone based on the two distinctive species which characterize it (Figure 10). Its reproducibility is low as no other brachiopod species have been recovered from the top of the formation in other sections.

The Squamularia sp. B-M. bassa Biozone and the H. kiangsiensis-N. (N.) asseretoi Biozone have in common seven species: M. bassa n. sp., P. rutehiana n. sp., B. yanagidai, K. bistriata, O. aff. O. husseinii, O. vediensis and Squamularia sp. A. The R. exile-R. gemmellaroi has no species in common with the lower biozones.

In conclusion the locality Khouban Pass and the sections Dorud and Ruteh, representing the basal part of the Ruteh Limestone are correlatable by the Squamularia sp. B-M. bassa Biozone, whereas the sections of Mangol Restaurant 1 and Shirinabad, representing the middle-upper part of the formation, are correlatable by the H. kiangsiensis-N. (N.) asseretoi Biozone, which has the maximum biodiversity (Figure 10).

AGE OF THE RUTEH LIMESTONE

Gaetani et al. (2009) have discussed the age of the Ruteh Limestone giving it a Wordian–Capitanian age, based on the fusulinids Pseudofusulina padangensis (Lange), Yangchienia haydeni Thompson, and species of Codonofusiella, Minojapanella, and Shubertella. The authors correlated the Ruteh Limestone to the upper Gnishik and lower Arpa horizons of the Middle Permian of Transcaucasia, which correspond to the Wordian–Capitanian of the standard stratigraphic scale (e.g. Kotlyar et al., 1989; Leven, 1998; Angiolini et al., 2008 and refs. therein). The topmost part of the formation along the Ruteh type-section are interpreted to correspond to part of the Khachik Horizon, which is Capitanian. Gaetani et al. (2009) found no conclusive evidence to exclude a Late Permian age for the upper part of the Ruteh Limestone, but later Angiolini and Carabelli (2010) pointed out that the Tyloplecta persica Biozone at the base of the overlying Nesen Formation may be latest Guadalupian, implying that the Ruteh Limestone was deposited entirely in the Guadalupian. This is supported by the emersion, karstification and latertic soils largely developed at the top of the Ruteh Limestone which are consistent with the occurrence of a major sea-level drop between the Guadalupian and the Lopingian, the most pronounced sea-level fall of the Permian (e.g. Shen and Shi, 2002; Haq and Shutter, 2008).

The brachiopod fauna described in the present paper confirms a Guadalupian age for the Ruteh Limestone. In fact most of the studied species are known from the Guadalupian only: Bilotina yanagidaiAngiolini and Bucher, 1999, occurring in the Wordian Khuff Formation of Oman (Angiolini and Bucher, 1999), Vediproductus vediensis Sarytcheva, 1965 and Orthothetina vediensis Sokolskaya, 1965, present in the Guadalupian Gnishik Formation of Transcaucasia (Sarytcheva, 1965), Kotlaia bistriata (Reed, 1944), occurring both in the Wordian Amb Formation of the Salt Range, Pakistan (Reed, 1944) and in the Wordian Khuff Formation of Oman (Angiolini and Bucher, 1999), Rostranteris exileGemmellaro, 1899 present in the Guadalupian Limestone of Palazzo Adriano of the Sosio Valley, Italy (Gemmellaro, 1899), Rostranteris gemmellaroiSmirnova and Grunt, 2002, observed in the Guadalupian Gundara Formation of Pamir (Smirnova and Grunt, 2002) and Omanilasma aff. O. husseinii Angiolini and Zarbo, 2006, present in the Wordian Khuff of Oman and in the Capitanian Midhnab Member Khuff Formation, of Saudi Arabia (Angiolini et al., 2006; Nicora et al., 2006).

In the middle part of the Ruteh Limestone there is the first occurrence of genera that range upward and have a wide distribution in the Lopingian, like Haydenella and Tyloplecta (Angiolini and Carabelli, 2010); these are mixed with genera that are typically Guadalupian, like Vediproductus, Chonostegoides and Urushtenoidea, suggesting a Capitanian age for the middle-upper part of the formation. The appearance of some Lopingian brachiopods in Capitanian successions has also been reported by Shen and Shi (2009) in South China and Verna et al. (2011) in Turkey. In addition, the Capitanian brachiopod faunas of South China have a more mixed character than those from Turkey (Verna et al., 2011) and from North Iran.

The brachiopod taxa collected in the basal part of the Ruteh Limestone seem to suggest a Wordian age.

SYSTEMATIC PALAEONTOLOGY

All the described specimens are housed in the Palaeontological Museum of the Department of Earth Sciences “A. Desio”, University of Milan, Italy. Specimens are registered with a prefix MPUM followed by a four to five digit number. The systematic study follows the classifications of Racheboeuf in Williams et al. (2000a) for the chonetidines, Brunton et al. in Williams et al. (2000b) for the productidines and strophalosiidines, Williams and Brunton in Williams et al. (2000b) for the orthotetidines, Williams and Harper in Williams et al. (2000b) for the orthids, Alvarez and Rong in Williams et al. (2002) for the athyridids, Carter and Gourvennec in Williams et al. (2006) for the reticularioids, Carter in Williams et al. (2006) for the pennospiriferinoids, Jin and Lee in Williams et al. (2006) for the cryptonelloids and Jin et al. in Williams et al. (2006) for the dielasmatoids.

Subphylum RHYNCHONELLIFORMEA Williams et al., 1996

Class STROPHOMENATA Williams et al., 1996

Order PRODUCTIDA Sarytcheva and Sokolskaya, 1959

Suborder CHONETIDINA Muir-Wood, 1955

Superfamily CHONETOIDEA Bronn, 1862

Family RUGOSOCHONETIDAE Muir-Wood, 1962

Subfamily RUGOSOCHONETINAE Muir-Wood, 1962

Genus NeochonetesMuir-Wood, 1962

Subgenus Neochonetes (Nongtaia) Archbold, 1999

Type-species:Neochonetes (Nongtaia) taoniArchbold, 1999 from the Guadalupian of Thailand.

Remarks:Neochonetes (Nongtaia) differs from Neochonetes (Huangichonetes)Shen and Archbold, 2002 from the Lopingian of South China because of its less numerous costellae at the anterior margin; it differs from Neochonetes (Zechiella)Archbold, 1999 from the Guadalupian of Germany and from Neochonetes (Zhongyingia)Shen and Archbold, 2002 from the Lopingian of South China because of its coarser ornamentation and its more distinct and deeper sulcus.

Neochonetes (Nongtaia) asseretoi (Fantini Sestini, 1964) (Fig. 11 a, b)

1964 Neochonetes asseretoi Fantini Sestini: p. 899; figs 1, 2. 1999 Neochonetes (Nongtaia) asseretoi Archbold: p. 76.

Material: Six ventral valves: MPUM 10753 (IR638-5-10, IR642-2, IR648A-133), MPUM 10754 (IR643-9), MPUM 10755 (IR648A-151).

Figured material: Two ventral valves: MPUM 10754 (IR643-9), MPUM 10755 (IR648A-151).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Small sized convex ventral valve with the maximum convexity in the posterior region; subrectangular to subquadrate outline; maximum width ranging between 3.4 and 6.9 mm, corresponding length respectively 2.2 and 5.2 mm; flat, quite large and distinct ears; median sulcus widening and shallowing anteriorly.

Ornamentation of coarse radial capillae increasing their number by bifurcation at the anterior margin; small spines at both sides of the umbo. Shell substance pseudopunctate.

Discussion:Neochonetes asseretoiFantini Sestini, 1964 has been assigned by Archbold (1999) to the subgenus Neochonetes (Nongtaia)Archbold, 1999 because of its small size, its subquadrate outline, its ventral sulcus and its distinct ornamentation of capillae bifurcating anteriorly. It differs from Neochonetes (Nongtaia) taoni by its sulcus, that tends to become wider and shallower anteriorly, whereas in the type-species tends to become narrower and deeper in the anterior region.

Stratigraphic and geographic occurrence:Neochonetes (Nongtaia) asseretoi has been found in the Guadalupian Ruteh Limestone of North Iran (Fantini Sestini, 1964–1965b).

Suborder PRODUCTIDINA Waagen, 1883

Superfamily PRODUCTOIDEA Gray, 1840

Family PRODUCTELLIDAE Schuchert, 1929

Subfamily PRODUCTININAE Muir-Wood and Cooper, 1960

Tribe CHONETELLINI Licharew, 1960

Genus Haydenella Reed, 1944

Type-species:Productus kiangsiensisKayser, 1883 from the Lopingian of South China.

Remarks:Haydenella differs from Ogbinia Sarytcheva in Ruzhentsev and Sarytcheva, 1965 from the Guadalupian of Transcaucasia because of its equidimensional outline, by the presence of rugae on the ears and spines scattered on the corpus of the valve, and because of its trifid cardinal process; it differs from CelebetesGrant, 1976 from the Guadalupian of Thailand, by the presence of costae and from Chonetella Waagen, 1884 from the Guadalupian and the Lopingian of the Salt Range, Pakistan mainly because the latter has a strongly nasute outline, it lacks ribs and spines on the corpus and it has strong lateral ridges.

Haydenella kiangsiensis (Kayser, 1883) (Fig. 11 c-j)

1883 Productus kiangsiensis Kayser: p. 185; pl. 26, figs 6–11.

1911 Productus kiangsiensis Kayser – Frech: p. 129; 168, 172, pl. 2, fig. 2; pl. 21, figs 3, 4.

1927 Avonia kiangsiensis (Kayser) – Chao: p. 125; pl. 14, figs 14–16.

1928 Thomasia kiangsiensis (Kayser) – Chao: p. 50; pl. 6, fig. 18.

1932 Linoproductus kiangsiensis (Kayser) – Huang: p. 46; pl. 3, figs 13–19. 1944 Productus (Haydenella) kiangsiensis (Kayser) – Reed: p. 78. 1948 Paramarginifera kiangsiensis (Kayser) – Branson: p. 448.

1960 Haydenella kiangsiensis (Kayser) – Muir-Wood and Cooper: p. 224; 395, pl. 65, figs 1–14.

1961 Argentiproductus kiangsiensis (Kayser) - Zhang and Ching: p. 411; pl. 3, figs 13, 14.

1964 Haydenella kiangsiensis (Kayser) – Yanagida: p. 8; text-fig. 3, pl. 2, fig. 1; pl. 3, fig. 4.

1965 Haydenella kiangsiensis (Kayser) – Ruzhentsev and Sarytcheva: pl. 38, figs 6–8.

1978 Haydenella kiangsiensis (Kayser) – Jing and Hu: p. 113; pl. 2, fig. 25.

1979 Haydenella kiangsiensis (Kayser) – Zhan: p. 81; pl. 5, figs 3, 4. 1984 Haydenella kiangsiensis (Kayser) – Yang: p. 218; pl. 33, fig. 9. 1995 Haydenella kiangsiensis (Kayser) – Zeng et al.: pl. 5, fig. 8.

2005 Haydenella kiangsiensis (Kayser) – Campi et al.: p. 111; pl. 1, figs Z, bb, cc, ee.

2008 Haydenella kiangsiensis (Kayser) – Li and Shen: p. 311; fig. 4 (7).

2009 Haydenella kiangsiensis (Kayser) – Shen and Clapham: p. 721; pl. 1, fig. 28; pl. 2, fig. 1.

Material: Twenty-four articulated specimens: MPUM 10756 (IR642-6, IR643-6-7, IR644bis-2, IR644D-10-17, IR645-2-5, IR646-5, IR647-3, IR647bis-1, IR648-2, IR648A-3-17-28-74-96-114-146-155-164), MPUM 10757 (IR644bis-3), MPUM 10758 (IR648A-147-148); twenty-three ventral valves: MPUM 10759 (IR642-3-7, IR644D-9, IR648-10, IR648A-5-6-7-14-15-19-29-51-53-55-80-86-107-116-117-124-141-156), MPUM 10760 (IR644bis-1); fourteen dorsal valves: MPUM 10761 (IR644D-3-20-23, IR645-4-11, IR648A-12-27-32-91-93-103), MPUM 10762 (IR648A-109), MPUM 10763 (IR648A-110), MPUM 10764 (IR648A-123); fragments: MPUM 10765 (IR638-8, IR641-2, IR642-1, IR643-8, IR644D-5-6-7-8-11-12-13-14-15-16-18-26-27, IR645-1-3-6-7-8-9-12-15-16-17-18-19-20, IR646-4-7-9-10-11-12-13-15, IR647-4-5-6, IR647bis-3-4-5, IR648-8-9, IR648A-1-2-20-25-26-31-44-50-54-56-58-64-69-70-75-76-77-79-81-82-83-87-92-101-104-105-108-111-118-122-125-130-135-136-137-139-140-152-153-157-163-168-170).

Figured material: Three articulated specimens: MPUM 10757 (IR644bis-3), MPUM 10758 (IR648A-147-148); one ventral valve: MPUM 10760 (IR644bis-1); three dorsal valves: MPUM 10762 (IR648A-109), MPUM 10763 (IR648A-110), MPUM 10764 (IR648A-123).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium sized concavo-convex shell with transverse subrectangular to suboval outline; maximum width ranging between 9.4 and 22.2 mm, corresponding length respectively 8.1 and 17.5 mm; cardinal margin straight but with crenulation determined by the ornamentation; anterior commissure rectimarginate; pseudopunctate shell. Ventral valve convex, swollen with umbo slightly projected over the hinge; ears small and triangular, well distinct from the corpus of the valve; weak ventral sulcus. Dorsal valve concave with small umbo; dorsal fold absent. Ornamentation of ventral valve consisting in radial costellae, numbering 10 per 5 mm, absent at the umbo, bifurcating anteriorly in some specimens; faint growth lines and rugae on the ears perpendicular to the cardinal margin; spines arranged in a row separating the ears from the rest of the valve and rarely scattered on the corpus. Ornamentation of dorsal valve similar to that of ventral valve. Interior of dorsal valve with a quite high bilobed cardinal process.

Discussion:Haydenella kiangsiensis differs from Haydenella khasorensis (Reed, 1944) from the Guadalupian and the Lopingian of the Salt Range, Pakistan because of its more transverse outline and its smaller umbo; also the ornamentation is different: Haydenella khasorensis has radial costellae starting from the umbo and coalescing at midlength into coarser and sinuous costellae, that then separate again anteriorly. Haydenella minuta Sarytcheva, 1965 from the Lopingian of Transcaucasia is different because it has a smaller size and a smaller number of rugae on the ears; Haydenella buravasiGrant, 1976 from the Guadalupian of South Thailand differs by its larger size and its stronger ornamentation; finally Haydenella elongataLiao, 1980 from the Lopingian of China is different because it has a more elongated outline.

Stratigraphic and geographic occurrence:Haydenella kiangsiensis has been found in the Changhsingian Lyttonia Bed of South China (Kayser, 1883), in the Upper Guadalupian–Wuchiapingian Wargal Formation of the Salt Range, Pakistan (Reed, 1944), in the Wuchiapingian of Transcaucasia (Sarytcheva, 1965), in the Guadalupian of Malaysia (Campi et al., 2005), in the Lopingian of South China (Li and Shen, 2008) and in the Wuchiapingian Episkopi Formation of Greece (Shen and Clapham, 2009).

Haydenella aff. H. khasorensis (Reed, 1944) (Fig. 11 k)

1965b Haydenella khasorensis – Fantini Sestini: p. 50; pl. 3, fig. 10.

Material: One figured ventral valve: MPUM 10766 (IR648-1).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium sized convex ventral valve with transverse subrectangular outline; maximum width 15.2 mm, corresponding length 12.7 mm; umbo large and slightly projected over the hinge; cardinal margin straight but with crenulation determined by the ornamentation; ears small, triangular and distinct; flattening anteriorly; pseudopunctate shell. Ornamentation of fine radial and sinuous costellae starting from the umbo and becoming coarser anteriorly; they tend to bifurcate near the geniculation, to coalesce with the spine bases and then to separate anteriorly to the spine bases; spine bases scattered on the valve; a row of poorly preserved spines separates the ears from the flanks; rugae on the ears arranged perpendicularly to the hinge.

Discussion: This specimen is similar to Haydenella khasorensis (Reed, 1944) for the ornamentation, but it differs slightly by its more transverse outline and its less swollen valve.

Stratigraphic and geographic occurrence:Haydenella khasorensis has been found in the Upper Guadalupian–Wuchiapingian Wargal Formation of the Salt Range, Pakistan (Reed, 1944) and in the Guadalupian Ruteh Limestone of North Iran (Fantini Sestini, 1965b).

Haydenella eminens n. sp. (Fig. 11 l, m)

Holotype: A ventral valve: MPUM 10770 (IR648A-73).

Derivation of the name:eminens from the latin emerging to indicate its anterior nasute protrusion.

Material: Two articulated specimens: MPUM 10767 (IR648A-102-106); nine ventral valves: MPUM 10768 (IR641-1-3-5, IR645-14, IR648-7, IR648A-112-149), MPUM 10769 (IR646-8), MPUM 10770 (IR648A-73).

Figured material: Two ventral valves: MPUM 10769 (IR646-8), MPUM 10770 (IR648A-73).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Diagnosis: Medium sized Haydenella with fine costellae, occasionally coalescing into coarser ones, and ventral nasute protrusion anterior to midlength.

Description: Medium sized concavo-convex shell with suboval outline; maximum width ranging between 13 and 18.5 mm, length ranging between 15 and 18.4 mm; cardinal margin straight but with crenulation determined by the ornamentation; nasute protrusion anteriorly that starts anteriorly to midlength. Ventral valve convex, with maximum convexity posteriorly; trail long and less convex than the visceral disk; ears small, triangular and distinct; pseudopunctate shell. Ornamentation of fine costellae, numbering 13 per 5 mm, absent at the umbo; in the median part of the valve coarser costellae seem to be formed by two finer ones; weak growth lines; 4–5 rugae on the ears arranged perpendicularly to the hinge; few spines separate the ears from the corpus; rare spine bases scattered on the valve.

Discussion: The small to medium sized shell, the lack of costellae at the umbo, and the occurrence of rugae on the ears, of a row of spines between the ears and the corpus and of spines scattered on the valve indicate that these specimens belong to the genus HaydenellaReed, 1944. The distinctive character of Haydenella eminens n. sp. is the nasute protrusion anteriorly. However, it does not belong to the genus Chonetella Waagen, 1884 because in the latter the nasute protrusion is more prominent and the ornamentation is different. Haydenella eminens n. sp. differs from Haydenella nasutaZeng, 1993 from the Changhsingian of China because of its less prominent nasute protrusion and its finer ornamentation.

Genus Ogbinia Sarytcheva in Ruzhentsev and Sarytcheva, 1965

Type-species:Ogbinia dzhagrensis Sarytcheva, 1965 from the Guadalupian of Transcaucasia.

Remarks:Ogbinia differs from Chonetella Waagen, 1884 from the Guadalupian and the Lopingian of the Salt Range, Pakistan because the latter has numerous spines along the cardinal hinge, a prominent nasute protrusion and a trilobed cardinal process; Ogbinia differs from HaydenellaReed, 1944 from the Lopingian of South China because it lacks rugae on the ears and spines on the dorsal valve and because it has a unifid cardinal process.

Ogbinia sp. ind. (Fig. 11 n)

Material: One figured articulated specimen: MPUM 10771 (IR643-1).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium sized concavo-convex shell with suboval outline; maximum width 13.7 mm, maximum length 14.8 mm; cardinal margin straight; pseudopunctate shell. Only part of the ventral valve is preserved in correspondence to the cardinal margin and the anterior commissure; small and triangular ears. Dorsal valve preserved as external cast, with thickened shell substance at the dorsal umbo. Ornamentation of radial capillae and concentric filae.

Discussion: The suboval outline, the lack of rugae on the ears and the presence of a thickening anteriorly to the dorsal umbo allows the specimen to be assigned to the genus Ogbinia Sarytcheva, 1965. It differs from Ogbinia productinaeformis Sarytcheva, 1965 from the Guadalupian of Transcaucasia because of its larger size and its more elongated outline; it is similar to Ogbinia dzhagrensis Sarytcheva, 1965 from the Guadalupian of Transcaucasia by its size and outline, but the lack of diagnostic character in the Iranian specimen makes impossible to offer a specific attribution.

Subfamily MARGINIFERINAE Stehli, 1954

Tribe MARGINIFERINI Stehli, 1954

Genus Entacanthadus Grant, 1993

Type-species:Entacanthadus chioticus Grant, 1993 from the Guadalupian of Greece.

Remarks: According to Grant (1993) the lack of rugae and costellae distinguishes Entacanthadus from Marginifera Waagen, 1884 from the Permian of Asia; EchinaurisMuir-Wood and Cooper, 1960 from the Cisuralian and the Guadalupian of Texas and CostispiniferaMuir-Wood and Cooper, 1960 from the Guadalupian of USA are different by the presence of dorsal spines, absent in Entacanthadus; DyschrestiaGrant, 1976 from the Guadalupian of Thailand lacks dorsal spines and has a dorsal marginal rim, whereas SpinomarginiferaHuang, 1932 from the Guadalupian and the Lopingian of Asia has a larger size and more numerous spines.

?Entacanthadus sp. ind. (Fig. 11 o)

Material: Two articulated specimens: MPUM 10772 (IR657-7), MPUM 10773 (IR659-3).

Figured material: One articulated specimen: MPUM 10773 (IR659-3).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Small sized concavo-convex shell with transverse subrectangular outline; maximum width 12.9–13 mm, maximum length 9.7–11 mm; cardinal margin straight; anterior commissure rectimarginate. Ventral valve convex, slightly swollen; small ears, poorly preserved; pointed umbo, slightly prominent on the hinge; weak ventral sulcus, more evident anteriorly. Dorsal valve weakly concave with little umbo and small and flat ears. Ornamentation of ventral valve with approximately eight spines arranged in two or three rows on flanks of the umbo and scattered on the valve. Ornamentation of dorsal valve nearly absent, with faint growth lines and no spines.

Discussion: Iranian specimens have a small size, smooth valves and spines only on the ventral valve; because of these characters they probably belong to the genus Entacanthadus Grant, 1993. They differ from the specimens figured by Grant (1993, fig. 12) because they have a more transverse outline, less swollen valves and a weak ventral sulcus; moreover we could not observe the set of dorsal trails described by Grant. The lack of dorsal spines excludes its inclusion in EchinaurisMuir-Wood and Cooper, 1960, in ComuquiaGrant, 1976 and in DyschrestiaGrant, 1976.

Genus OtariellaWaterhouse, 1978

Type-species:Marginifera otariaGrant, 1976 from the Guadalupian of Thailand.

Remarks: According to Waterhouse (1978),Otariella differs from Marginifera Waagen, 1884 from the Guadalupian of the Salt Range, Pakistan by its greater number of spines; Grant (1976), on the other hand, observes that Marginifera otaria differs from other species of Marginifera by its fewer spines; the two statements are thus opposite. Based on the observation of the specimens figured by Grant (1976), it seems that Otariella has a smaller number of spines, as Grant has affirmed. Otariella differs from Entacanthadus Grant, 1993 from the Guadalupian of Greece, because the latter has smaller ears, a set of dorsal trails and it lacks a ventral sulcus; ProbolioniaCooper, 1957 from the Cisuralian of the USA is different because it has a set of dorsal trails and a stronger ornamentation, consisting of costae and rugae forming a reticulation on the visceral disk.

?Otariella sp. ind. (Fig. 11 p–s)

Material: Ten ventral valves: MPUM 10774 (IR656-1-4, IR657-1, IR659-2-4-5), MPUM 10775 (IR657-2), MPUM 10776 (IR657-5), MPUM 10777 (IR657-6), MPUM 10778 (IR660-1).

Figured material: Four ventral valves: MPUM 10775 (IR657-2), MPUM 10776 (IR657-5), MPUM 10777 (IR657-6), MPUM 10778 (IR660-1).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium sized convex and strongly swollen ventral valve with subrectangular outline; maximum width ranging between 11.9 and 14.6 mm, maximum length ranging between 8.8 and 12.8 mm; curved umbo, slightly prominent on the hinge; short visceral disk and long and steep trail; ears poorly preserved with auricular chambers in some specimens; deep ventral sulcus starting near the geniculation, widening anteriorly and delimited laterally by two ridges; pseudopunctate shell.

Valve smooth, except for the spines scattered on the corpus, numbering up to 15; in some specimens spines seem to be arranged in concentric rows; spines absent in the sulcus.

Discussion: The Iranian specimens have a strongly swollen ventral valve, auricular chambers, a deep sulcus and a smooth valve; because of these characters they probably belong to the genus Otariella; however, the characteristic twisted ears are not preserved in our specimens, so the assignment to this genus is uncertain. The Iranian specimens cannot be placed in the genus Entacanthadus Grant, 1993 because of their more swollen ventral valve and because of the presence of the ventral sulcus; they do not belong to the genus Echinauris Muir-Wood and Cooper, 1960 because of their more swollen ventral valve, their more curved umbo and their smaller number of ventral spines; finally they do not belong to the genus Marginifera Waagen, 1884 because the latter has ribs and more numerous spines.

Genus SpinomarginiferaHuang, 1932

Type-species:Spinomarginifera kueichowensisHuang, 1932 from the Guadalupian and the Lopingian of South China.

Remarks: According to Huang (1932),Spinomarginifera lacks dorsal spines; however Nakamura in Nakazawa (1973) and Shen (written communication, 2010) observe that all the species of Spinomarginifera have dorsal spines. Spinomarginifera differs from Marginifera Waagen, 1884 from the Guadalupian of the Salt Range, Pakistan because it has more numerous and longer spines and lacks ribs and rows of spines on the flanks; Haydenoides Zhan in Yang et al., 1977 from the Permian of China and RugosomarginiferaXu, 1987 from the Permian of China are considered synonyms of Spinomarginifera by Brunton et al. in Williams et al. (2000b); however the first is different from Spinomarginifera by its stronger ribs and rugae and the latter is different by its stronger ornamentation and by the presence of a shorter median septum.

Spinomarginifera sp. ind. (Fig. 11 t)

Material: One figured ventral valve: MPUM 10779 (IR648A-52).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Small sized convex ventral valve; pseudopunctate shell. Ornamentation of concentric and irregular rugae on the visceral disk, more evident on the flanks; they tend to coalesce into one rugae and then to separate into two distinct rugae; long spines, up to 3.5 mm long; subcircular spine bases numerous on the flanks, often arranged on the rugae, rarely scattered on the corpus of the valve.

Discussion: The ornamentation allows assignment of this specimen to the genus Spinomarginifera; it differs from Spinomarginifera kueichowensis and from Spinomarginifera pseudosintanensisHuang, 1932 from the Lopingian of China because it lacks a ventral sulcus; of the species of Spinomarginifera described by Fantini Sestini (1965a, b) the present specimen is mostly closest to S. helica (Abich, 1878), but it differs because it lacks a ventral sulcus and it has stronger rugae. The revision of the material of Fantini Sestini (1965a, b) shows that only S. helica and S. spinosocostata (Abich, 1878) are well represented, the other specimens being only determinable at generic level.

Family PRODUCTIDAE Gray, 1840

Subfamily LEIOPRODUCTINAE Muir-Wood and Cooper, 1960

Tribe TYLOPLECTINI Termier and Termier, 1970

Genus TyloplectaMuir-Wood and Cooper, 1960

Type-species:Productus scabriculus mut. nankingensisFrech, 1911 from the Cisuralian of China.

Remarks: According to Brunton et al. in Williams et al. (2000 b) the radial ornamentation of Tyloplecta consists of elongated spine bases posteriorly that become ribs at midlength. Tyloplecta differs from RugatiaMuir-Wood and Cooper, 1960 from the Cisuralian of the USA and from CostiferinaMuir-Wood and Cooper, 1960 from the Guadalupian and the Lopingian of the Salt Range, Pakistan by its less sulcate valve, its smaller ears and its more regular ornamentation.

Tyloplecta cf. T. yangtzeensis (Chao, 1927) (Fig. 12 a)

1965b Tyloplecta cf. T. yangtzeensis (Chao) – Fantini Sestini: p. 53; pl. 5, fig. 12.

Material: One figured ventral valve: MPUM 10780 (IR640B-1); fragment: MPUM 10781 (IR647-1).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium sized, convex ventral valve, slightly swollen, quite flat in transverse section; cardinal margin straight; small, pointed umbo, slightly projected over the hinge; median flattening; pseudopunctate shell. Ornamentation of rugae and ribs, creating a clear reticulation; rugae more evident and closer on the visceral disk, flanks and ears, further apart and weaker anteriorly; regular ribs diverging and coarsening anteriorly; rare coarse and subcircular spine bases arranged as follows: 1) close along cardinal margin, 2) on the rugae on the flanks and 3) on the ribs on the trail, where the spine bases are larger than the ribs themselves (1 mm wide).

Discussion: Diagnostic characters to distinguish Tyloplecta yangtzeensis from other species of Tyloplecta are the length/wide ratio, the shape of the umbo and the ornamentation. Our specimen is poorly preserved, so it is not possible to observe the length/wide ratio; however the small, pointed umbo and the ornamentation are very similar to those of Tyloplecta yangtzeensis. Tyloplecta cf. T. yangtzeensis differs from Tyloplecta persicaFantini Sestini, 1966 from the Lopingian of North Iran by its smaller and more prominent umbo and by its more evident reticulation.

Stratigraphic and geographic occurrence:Tyloplecta yangtzeensis has been found in the Changhsingian Lyttonia Bed of South China (Kayser, 1883), in the Guadalupian Jisuhonguer Limestone of Mongolia (Chao, 1927), in the Permian of Southwest China (Huang, 1932), in the Lopingian of West Serbia (Simic, 1933), in the upper Guadalupian - Wuchiapingian Wargal Formation of the Salt Range, Pakistan (Reed, 1944), in the Lopingian of Slovenia (Ramovs, 1958), in the Lopingian of North Hungary (Schreter, 1963), in the Permian of Central Thailand (Yanagida, 1964), in the Wuchiapingian of Transcaucasia (Sarytcheva, 1965), and in the Guadalupian Ruteh Limestone and the Lopingian Nesen Formation of North Iran (Fantini Sestini, 1965b, 1966; Angiolini and Carabelli, 2010).

Subfamily DICTYOCLOSTINAE Stehli, 1954

Genus ReticulatiaMuir-Wood and Cooper, 1960

Type-species:Productus huecoensisKing, 1931 from the Cisuralian of USA.

Remarks:Reticulatia differs from SquamariaMuir-Wood and Cooper, 1960 from the Cisuralian of Texas because of its wider ventral valve, its more evident reticulation, its smaller number of spines and because it lacks spines on its dorsal ears. Moreover the lateral ridges in Reticulatia are not extended onto the lateral margins, as in Squamaria. CallytharrellaArchbold, 1985 from the Cisuralian of Australia is different because it has a deep ventral sulcus, fasciculated ribs, dorsal marginal ridges and a cardinal process anteriorly bilobed.

Reticulatia sp. ind. (Fig. 12 b)

Material: One figured articulated specimen: MPUM 10782 (GC10-1).

Occurrence: North Iran, Ruteh Limestone, Ruteh section loose block.

Description: Large sized concavo-convex shell with subquadrate outline; width 54 mm, length 56.3 mm; cardinal margin straight. Ventral valve with short, convex visceral disk and long, strongly curved trail; strongly recurved umbo, slightly prominent on the hinge; narrow and shallow sulcus; presence of a ginglymus. Dorsal valve concave with flat, triangular ears. Ornamentation on ventral valve consisting of costae, rugae and spines; costae starting from the umbo, slightly diverging anteriorly, sometimes bifurcating; costae coarser on the median part of the valve, finer laterally, numbering 4 per 5 mm at 35 mm from the umbo, 6 per 5 mm on the flanks; rugae only on the visceral disk, more evident on the flanks, weaker in the median part of the visceral disk, forming a faint reticulation; small spine bases arranged in the furrow between the ears and the corpus, scattered on the visceral disk and on the costae on the trail. Ornamentation on dorsal valve of rugae and costae that form a marked reticulation.

Discussion: This specimen has been assigned to the genus Reticulatia because of its large size and its ornamentation; the reticulation is less evident than on the other species of Reticulatia, but this may be due to the poor preservation of our specimen. It is similar to Reticulatia chitralisAngiolini, 1995 from the Guadalupian of Karakorum, Pakistan, but it differs by its smaller size and its more transverse outline.

The specimen described by Fantini Sestini (1965b) as Reticulatia ? sp. ind. is only a fragmentary external cast of a ventral valve so it is impossible to compare it with the specimen under examination. The same holds true for the specimen determined, by the same author, to be Costiferina cf. C. indica (Waagen, 1884).

Superfamily ECHINOCONCHOIDEA Stehli, 1954

Family ECHINOCONCHIDAE Stehli, 1954

Subfamily JURESANIINAE Muir-Wood and Cooper, 1960

Tribe JURESANIINI Muir-Wood and Cooper, 1960

Genus BilotinaReed, 1944

Type-species:Strophalosia (Bilotina) subtectaReed, 1944 from the Guadalupian of the Salt Range, Pakistan.

Remarks:Muir-Wood and Cooper (1960) and Grant (1976) observed that the ornamentation of the ventral valve of Bilotina consisted of long spine bases and not of costae, as described by Reed (1944). Grant (1976) considered buttress plates originating from the cardinal process to be a diagnostic character of Bilotina; however, according to Brunton et al. (1995), true buttress plates die out in the Early Carboniferous and the plates present in Bilotina are ridges connecting the raised muscle platform.

Bilotina yanagidaiAngiolini and Bucher, 1999 (Fig. 12 c–f)

1999 Bilotina yanagidai Angiolini and Bucher: p. 686; figs 14, 17–22.

2011 Bilotina yanagidai – Verna and Angiolini in Verna et al.: p. 21; pl. 2, figs 9–17.

Material: One articulated specimen: MPUM 10783 (IR648A-71); six ventral valves: MPUM 10784 (IR48-24, IR51-4, IR123-84, IR448bis-2), MPUM 10785 (IR123-43), MPUM 10786 (GC10-3); fragment: MPUM 10787 (IR644D-24).

Figured material: One articulated specimen: MPUM 10783 (IR648A-71); two ventral valves: MPUM 10785 (IR123-43), MPUM 10786 (GC10-3).

Occurrence: North Iran, Ruteh Limestone, Dorud section 36°00′18.3″N, 51°29′01.6″E; Dorud section loose block; Ruteh section loose block; Khouban Pass section, 36°01′50″N, 51°25′53.8″E; Mangol Restaurant 1 section, 36°14′58.2″N, 55°22′05.1″E; Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium sized, concavo-convex shell with subquadrate outline; maximum width ranging between 12.1 and 15.3 mm, length ranging between 10.5 and 16.7 mm; cardinal margin straight; pseudopunctate shell. Ventral valve convex, swollen with trail slightly longer than the visceral disk; recurved umbo. Dorsal valve with concave visceral disk. Ornamentation on ventral valve consisting of long spine bases simulating ribs, numbering 4–6 per 5 mm near the anterior commissure; rare and coarse spine bases (0.5 mm wide on the trail) arranged radially, in concentric rows or scattered on the valve; weak rugae on the visceral disk; dorsal valve with growth lines.

Discussion:Bilotina yanagidai differs from Bilotina acanthaWaterhouse and Piyasin, 1970 from the Wordian of Thailand by its more transverse outline, by its non-sulcate umbonal region and by its fewer spines; it differs from Bilotina subtectaReed, 1944 from the Guadalupian of the Salt Range, Pakistan because it lacks a ventral sulcus and because it has coarser and fewer spines.

Stratigraphic and geographic occurrence:Bilotina yanagidai has been found in the Wordian Khuff Formation of Southeast Oman (Angiolini and Bucher, 1999) and in the Guadalupian Pamucak Formation of Turkey (Verna et al., 2011).

Genus Vediproductus Sarytcheva in Ruzhentsev and Sarytcheva, 1965

Type-species:Vediproductus vediensis Sarytcheva, 1965 from the Guadalupian of Transcaucasia.

Remarks:Vediproductus is similar to JuresaniaFredericks, 1928 from the Permian of Asia but it differs because of the arrangement of the spines, because in Vediproductus the spines are quincuncially arranged posteriorly and present only on bands of strong relief; it differs from ParapulchratiaChan, 1979 from the Lopingian of China, because the latter has concentric and irregularly distributed spine bases, rugae which are stronger on the flanks and on the ears, and coarse spines on the ears; it differs from ChenxianoproductusLiao and Meng, 1986 from the Permian of China, because the latter has rounded spine bases, it lacks a ventral sulcus and it has a bilobed cardinal process; finally it differs from BathymyoniaMuir-Wood and Cooper, 1960 from the Cisuralian–Guadalupian of the USA by its weaker concentric bands and its shallower ventral sulcus. According to Shiino (2009)Vediproductus occurs less frequently than other Permian brachiopods in Asia, but it has been used for palaeogeographic reconstruction because of its characteristic distribution in the palaeoequatorial region.

Vediproductus vediensis Sarytcheva, 1965 (Fig. 12 g, h)

1965 Vediproductus vediensis Sarytcheva: p. 221; pl. 35, figs 1–3.

1965b Echinoconchus sp. ind. Fantini Sestini: p. 51.

Material: Two figured ventral valves: MPUM 10788 (IR448bis-1), MPUM 10789 (IR656-5).

Occurrence: North Iran, Ruteh Limestone, Mangol Restaurant 1 section, 36°14′58.2″N, 55°22′05.1″E; Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium to large sized, convex valve with subtriangular to subquadrate outline; maximum width ranging between 27.9 and 41.4 mm, corresponding length respectively 29 and 36.5 mm; umbo recurved, prominent on the hinge; umbonal region with steep flanks; ears small, poorly preserved; deep sulcus starting from the umbo and widening anteriorly. Ornamentation of concentric bands starting near the umbo, coarsening and more spaced anteriorly, closer on the flanks and on the ears; small spines and spine bases on the concentric bands arranged as follows: a) wide, swollen and elongate, then shortening anteriorly in the posterior part of the relieved band, b) smaller and not swollen in the anterior part of the relieved band.

Discussion:Vediproductus vediensis is very similar to Vediproductus punctatiformis (Chao, 1927) from the Permian of China, but the first differs by its subquadrate outline, its more swollen ventral valve, its smaller umbo and its more evident ventral sulcus; it differs from Vediproductus tongluensisLiang, 1990 from the Permian of China, by its more transverse, subtriangular outline and its more spaced concentric bands; it differs from Vediproductus mugenjinShiino, 2009 from the Capitanian of Japan mainly because the latter has concentric bands that present a typical sawtooth outline in cross-section.

Stratigraphic and geographic occurrence:Vediproductus vediensis has been found in the Guadalupian Gnishik Horizon of Transcaucasia (Sarytcheva, 1965) and in the Guadalupian Ruteh Limestone of North Iran (Fantini Sestini, 1965b).

Superfamily LINOPRODUCTOIDEA Stehli, 1954

Family LINOPRODUCTIDAE Stehli, 1954

Subfamily LINOPRODUCTINAE Stehli, 1954

Genus LinoproductusChao, 1927

Type-species:Productus coraD’Orbigny, 1842 from the Cisuralian of Bolivia.

Linoproductus aff. L. lineatus (Waagen, 1884) (Fig. 12 i, j)

Material: One figured articulated specimen: MPUM 10790 (IR648A-36); one figured ventral valve: MPUM 10791 (IR648A-23); fragment: MPUM 10792 (IR648A-37).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Large sized, concavo-convex shell with subquadrate to suboval outline; maximum width ranging between 31.9 and 36.2 mm, maximum length 30.1 mm; cardinal margin straight. Ventral valve convex and swollen; small umbo, slightly projected over the hinge; short and curved visceral disk; long trail; shallow sulcus on the trail, widening anteriorly. Dorsal valve concave with slightly concave visceral disk and long trail; small, flat, triangular ears. Ornamentation on ventral valve of costellae about 0.2 mm wide at the anterior margin, numbering 8–9 per 5 mm at the anterior commissure, finer at the umbo, coarser anteriorly, where some of them bifurcate; interspaces wider than the costellae (0.8–0.9 mm wide); marked rugae on the flanks and on the ears; rare spines; costellae seem to coalesce with the spines and then to separate anteriorly to the spines. Dorsal valve with costellae and 5–6 coarse rugae on the flanks and on the ears. Interior of dorsal valve with a trilobed cardinal process with the central lobe of larger size.

Discussion: The Iranian specimens are similar to Linoproductus lineatus (Waagen, 1884) from which they slightly differ because they have a less recurved umbo, only slightly projected over the hinge and they lack a dorsal fold; they differ from Linoproductus kasetiGrant, 1976 from the Permian of Thailand and from Linoproductus antonioi Verna and Angiolini, in Verna et al., 2011, from the Wordian of Oman and Turkey (Verna et al., 2011) by their deeper ventral sulcus, by their larger number of finer costellae and by their smaller spines. The specimens described by Fantini Sestini (1965b) differ by their lack of a ventral sulcus.

Stratigraphic and geographic occurrence:Linoproductus lineatus has been found in the upper Guadalupian–Wuchiapingian Wargal Formation of the Salt Range, Pakistan (Waagen, 1884), in the Lopingian of Chitichun, Himalaya (Diener, 1897), in the Guadalupian Jisuhonguer Limestone of Mongolia (Chao, 1927; Grabau, 1931), in the Lopingian of Slovenia (Ramovs, 1958), in the Permian of Yangtze Gorge Area, South China (Yang, 1984), in the Guadalupian of the Velebit Mountains, Croazia (Sremac, 1986), in the Guadalupian Shazipo Formation of West Yunnan, China (Shi and Shen, 2001), in the Guadalupian Moribu Formation of Central Japan (Tazawa, 2001), and in the Guadalupian of Slungai Toh, Pahang, Malaysia (Campi et al., 2005).

?Linoproductus sp. ind (Fig. 12 k)

Material: One figured dorsal valve: MPUM 10793 (GC10-4); fragment: MPUM 10794 (GC10-5).

Occurrence: North Iran, Ruteh Limestone, Ruteh section loose block.

Description: Large sized, concave valve with subrectangular, slightly transverse outline; cardinal margin straight; small ears; dorsal fold widening and becoming more evident anteriorly. Ornamentation of fine costellae starting from the umbo and of weak concentric rugae; small spines near the cardinal margin.

Discussion: This Iranian specimen has a subrectangular outline, a dorsal fold, radial costellae, concentric rugae and spines along the cardinal margin; for these characters it probably belongs to the genus Linoproductus; however the poor preservation does not allow a sure specific assignment; it differs from the specimens determined above as Linoproductus aff. L. lineatus mainly by the presence of an anteriorly evident fold.

Family MONTICULIFERIDAE Muir-Wood and Cooper, 1960

Subfamily AURICULISPININAE Waterhouse, 1986

Genus MagniplicatinaWaterhouse, 1983

Type-species:Cancrinella magniplicaCampbell, 1953 from the Cisuralian of Queensland, Australia.

Remarks:Magniplicatina is similar to the Permian–Carboniferous genus CancrinellaFredericks, 1928, but it differs because of its less deep corpus, its shorter trail, its more marked rugae and its coarser ventral spines and because it lacks dorsal spines; Magniplicatina differs from Costatumulus Waterhouse, 1986 from the Cisuralian of Australia by its coarser rugae and from CoolkilellaArchbold, 1993 from the Cisuralian of Australia because the latter has a more curved ventral valve, a strong geniculation of the dorsal valve and stronger rugae on the ears.

Magniplicatina sp. ind. (Fig. 12 l)

Material: One figured fragment of ventral valve: MPUM 10795 (IR649-1).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium sized, convex ventral valve. Ornamentation of weak, irregular and discontinuous rugae and of irregular costellae; spine bases widely spaced and larger than the costellae.

Discussion: The Iranian specimen has been assigned to the genus Magniplicatina for its irregular rugae and its coarse and widely spaced spine bases; unfortunately the cardinal margin and the anterior region of the valve are not preserved, so the assignment is based only on the ornamentation. It can be excluded from the genus Cancrinella because of its irregular rugae and its coarser and more widely spaced spine bases and from the genus Costatumulus because of its marked rugae. The specimen described by Fantini Sestini (1965b) as Cancrinella cancriniformis (Tschernyschew, 1889) is much smaller and has stronger rugation.

Suborder STROPHALOSIIDINA Schuchert, 1913

Superfamily AULOSTEGOIDEA Muir-Wood and Cooper, 1960

Family AULOSTEGIDAE Muir-Wood and Cooper, 1960

Subfamily CHONOSTEGINAE Muir-Wood and Cooper, 1960

Genus Chonostegoides Sarytcheva in Ruzhentsev and Sarytcheva, 1965

Type-species:Chonostegoides ogbinensis Sarytcheva, 1965 from the Guadalupian of Transcaucasia.

Remarks:Chonostegoides is similar to the genus ChonostegesMuir-Wood and Cooper, 1960 from the Cisuralian of Texas, but the former differs because it lacks an evident concentric ornamentation on the visceral disk of both valves and because it has stronger marginal ridges.

?Chonostegoides sp. ind. (Fig. 12 m, n)

Material: Two ventral valves: MPUM 10796 (IR638-2) MPUM 10797 (IR638-7); one dorsal valve: MPUM 10798 (IR638-1); fragment: MPUM 10799 (IR638-6).

Figured material: One ventral valve: MPUM 10797 (IR638-7); one dorsal valve: MPUM 10798 (IR638-1).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Small sized, concavo-convex shell with slightly transverse outline; maximum width at midvalve ranging between 7 and 9 mm, corresponding length ranging between 6.4 and 8.4 mm; cardinal margin straight. Ventral valve convex, slightly recurved; umbo large and slightly prominent on the hinge; visceral disk slightly longer than the trail; small ears. Dorsal valve concave, geniculated, with quite flat visceral disk and short, curved trail. Ornamentation of ventral valve consisting of growth lines on the visceral disk, becoming weak rugae on the ears and on the flanks; spines with coarse spine bases scattered on the valve; spine bases arranged as follows: a) subcircular and closer on the flanks and on the ears, b) widely spaced on the rest of the valve, where they are arranged on the ribs or, near the anterior commissure in the interspaces among the ribs themselves; ribs, numbering 6 per 5 mm, formed by elongate spines, which anteriorly give origin to tubular structures. Ornamentation of dorsal valve similar to that of ventral valve.

Discussion: The difference between Chonostegoides and Chonosteges is mainly based on the internal characters, which are not shown in our specimens; they probably belong to Chonostegoides, as they lack an evident concentric ornamentation.

Genus Urushtenoidea Jing and Hu, 1978

Type-species:Urushtenia chaoi Jing, 1963 from the Cisuralian of South China.

Remarks:Urushtenoidea is similar to the genus UrushteniaLicharew, 1935 from the Cisuralian of Russia, but it differs by its more marked ventral geniculation (often more than 60°), its flat dorsal visceral disk, its concentric lamellae, its rows of erected spines on the trail, its prominent ventral marginal ridge and because it lacks a ventral rim projected anteriorly and a median septum.

?Urushtenoidea sp. ind. (Fig. 12 o)

Material: One figured dorsal valve and its external cast: MPUM 10800 (IR646-2-3).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Small sized, strongly geniculated dorsal valve with subrectangular outline; width 9.6 mm, corresponding length 6.7 mm; visceral disk long, slightly concave, quite flat; trail short and concave; cardinal margin straight; small ears and large umbo; weak dorsal fold. Ornamentation of fine costae diverging from the umbo and coarsening on the trail; irregular concentric lamellae on the trail; weak rugae on the ears. Interior of dorsal valve with a short median septum, shorter than midlength.

Discussion: The ornamentation of costae, faint rugae and concentric lamellae and the presence of a median septum allow this specimen to be assigned to the genus Urushtenoidea; however the lack of diagnostic characters does not make sure this assignment; it differs from Urushtenia because of its concentric lamellae, its shorter trail and its median septum. The stratigraphic distribution of Urushtenia is from Upper Carboniferous to Artinskian, whereas Urushtenoidea is present from Artinskian to upper Guadalupian, both not extending to Lopingian.

Order ORTHOTETIDA Waagen, 1884

Suborder ORTHOTETIDINA Waagen, 1884

Superfamily ORTHOTETOIDEA Waagen, 1884

Family MEEKELLIDAE Stehli, 1954

Subfamily MEEKELLINAE Stehli, 1954

Genus OrthothetinaSchellwien, 1900

Type-species:Orthothetes persicus Schuchert in Schuchert and LeVene, 1929 from the Guadalupian of Iran.

Remarks:Orthothetina differs from Meekella White and St. John, 1867 from the Permian of Iowa, because it lacks plicae and it has thin dental plates converging separately to the valve floor; it differs from PerigeyerellaWang, 1955 from the Lopingian of China because of its subparallel dental plates, not forming a spondylium.

Orthothetina vediensis Sokolskaya in Ruzhentsev and Sarytcheva, 1965 (Fig. 12 p–r)

1965 Orthothetina vediensis Sokolskaya: p. 203; pl. 29, figs 13 a–d.

Material: Two articulated specimens: MPUM 10801 (IR51-19), MPUM 10802 (IR123-65); two dorsal valves: MPUM 10803 (IR48-43), MPUM 10804 (IR644D-19).

Figured material: One articulated specimen: MPUM 10801 (IR51-19); one dorsal valve: MPUM 10804 (IR644D-19).

Occurrence: North Iran, Ruteh Limestone, Dorud section 36°00′18.3″N, 51°29′01.6″E; Dorud section loose block; Khouban Pass section, 36°01′50″N, 51°25′53.8″E; Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium sized, biconvex shell with subrectangular outline; maximum width at midvalve, ranging between 23.5 and 32.4 mm, length ranging between 19.1 and 24.6 mm; cardinal margin straight, more than two-thirds of the shell width; anterior commissure sulcate. Ventral valve slightly convex posteriorly, flat anteriorly; umbo pointed and large; interarea apsacline, triangular, large and not very high, with pseudodeltidium with a convex median monticulus. Dorsal valve more convex posteriorly; sulcus starting near midvalve, widening and deepening anteriorly. Ornamentation on both valves of costellae, numbering 13–15 per 5 mm at the anterior margin. Interior of ventral valve with two short and subparallel dental plates, not joined on the valve floor. Interior of dorsal valve with socket plates forming an angle of 60°.

Discussion:Orthothetina vediensis differs from Orthothetina iljinae Sokolskaya, 1965 from the Guadalupian of Transcaucasia by its smaller size, its more rounded outline, its more convex valves and its finer costellae; it differs from Orthothetina armeniaca (Von Arthaber, 1900) from the Permian of Djulfa, Transcaucasia because the latter lacks a dorsal median sulcus and it has fewer costellae.

A single dorsal valve MPUM 10805 (IR648A-9) from the Shirinabad section has been determined as Orthothetina sp. ind. as it has the internal characters of the genus (separate dental plates), but it is larger than O. vediensis, with fewer costellae (11–12 per 5 mm at 10 mm from the umbo) and a shallow sulcus. The poor preservation of this specimen does not allow the assignment to any other species.

Stratigraphic and geographic occurrence:Orthothetina vediensis has been found in the Guadalupian Gnishik Formation of Transcaucasia (Sokolskaya, 1965).

Genus PerigeyerellaWang, 1955

Type-species:Perigeyerella costellataWang, 1955 from the Lopingian of China.

Remarks:Perigeyerella has dental plates which are joined in the umbonal region to form an elevated spondylium, like GeyerellaSchellwien, 1900 from the Guadalupian of Sicily and OmboniaCaneva, 1906 from the Guadalupian of Sicily and the Lopingian of the Southern Alps; anteriorly it changes into a sessile spondylium, like SiceliaGortani and Merla, 1934 from the Permian of Sicily, and then terminates with parallel plates on the valve floor, like OthothetinaSchellwien, 1900 from the Guadalupian of Iran and Meekella White and St. John, 1867 from the Permian of Iowa. Furthermore, Perigeyerella differs from Geyerella because it lacks plicae; it differs from Orthothetina and from Meekella by its apical spondylium; and it differs from Sicelia by its less conical ventral valve.

Perigeyerella rutehianan. sp. (Fig. 13 a–h; fig. 15 g–k)

Holotype: MPUM 10807 (IR648-3).

Derivation of the name:rutehiana from the Ruteh Limestone, where the species has been sampled.

Material: Seventeen articulated specimens: MPUM 10806 (IR644D-4, IR646-14, IR647-2, IR648-4-6, IR648A-18-39-150-154-159-176, IR649-20), MPUM 10807 (IR648-3), MPUM 10808 (IR648-5), MPUM 10809 (IR648A-119), MPUM 10810 (IR648A-120), MPUM 10811 (IR648A-173); three ventral valves: MPUM 10812 (IR648A-33-172), MPUM 10813 (IR648A-165); sixteen dorsal valves: MPUM 10814 (IR641-6, IR642-4, IR643-5, IR648A-4-16-35-38-43-65-113-138-160-171-175), MPUM 10815 (IR648A-158), MPUM 10816 (IR648A-167); fragments: MPUM 10817 (IR48-65; IR58-1; IR60-4; IR61-45-47; IR123-67-70; IR125-1-3-5-7; IR126-1; IR648A-13-66-84-90-94-97-115-142-143-145-161-162-174).

Figured material: Five articulated specimens: MPUM 10807 (IR648-3), MPUM 10808 (IR648-5), MPUM 10809 (IR648A-119), MPUM 10810 (IR648A-120), MPUM 10811 (IR648A-173); one ventral valve: MPUM 10813 (IR648A-165); two dorsal valves: MPUM 10815 (IR648A-158), MPUM 10816 (IR648A-167).

Occurrence: North Iran, Ruteh Limestone, Dorud section 36°00′18.3″N, 51°29′01.6″E; Ruteh section, 35°58′38.3″N, 51°32′28.9″E; Khouban Pass section, 36°01′50″N, 51°25′53.8″E; Shirinabad section, 36°53′46″N, 55°09′30″E.

Diagnosis: species of Perigeyerella characterized by a subcircular outline, few costellae, a shallow dorsal sulcus and a low, wide and triangular interarea.

Description: Medium to large sized, biconvex shell with subcircular outline; maximum width at midvalve, ranging between 19.4 and 59.2 mm, maximum length 33.6 mm; cardinal margin short and straight; anterior commissure rectimarginate to slightly sulcate. Ventral valve slightly convex; umbo narrow, pointed and sometimes slightly deformed; interarea triangular, apsacline, flat or slightly concave, wide and not very high; convex and narrow pseudodeltidium with a median monticulus. Dorsal valve more convex than the ventral valve with transverse suboval outline; shallow, but evident sulcus starting near the umbo and widening anteriorly. Ornamentation of both valves of costellae, numbering 10–12 per 5 mm at the anterior margin, where sometimes they bifurcate, 12–14 per 5 mm at midvalve; interspaces wider than the costellae themselves; weak growth lines and weak rugae on the flanks. Interior of ventral valve with dental plates forming a spondylium posteriorly, becoming subparallel and divergent anteriorly.

Discussion: The shape, the ornamentation and the internal characters allow these specimens to be assigned to the genus Perigeyerella; in particular the presence of a spondylium excludes its inclusion in Orthothetina. The distinctive characters are the low number of costellae, the subcircular outline, the shallow dorsal sulcus, and the low, wide and triangular interarea, that distinguish Perigeyerella rutehiana n. sp. from other species of Perigeyerella. More specifically, Perigeyerella rutehiana n. sp. differs from Perigeyerella costellataWang, 1955 by its shallower and wider sulcus, its lower and wider interarea and its fewer costellae; it differs from Perigeyerella raffaellaeAngiolini and Bucher, 1999 from the Wordian of Oman by its larger size, its lower and wider interarea and its fewer costellae. The specimen described as Streptorhynchus cf. S. lenticulare Waagen, 1884 by Fantini Sestini (1965b) belongs to the genus Perigeyerella, but differs from the new species by the absence of the dorsal sulcus.

Family SCHUCHERTELLIDAE Williams, 1953

Subfamily SCHUCHERTELLINAE Williams, 1953

Genus SchuchertellaGirty, 1904

Type-species:Streptorhynchus lensWhite, 1862 from the upper Famennian of Missouri, USA.

Remarks: According to Cooper and Grant (1974) the genus Schuchertella is characterized by: 1) the extropunctate shell; 2) the lack of dental plates; and 3) the vestigial dentifers, surrounded by socket plates and with no anterolateral extensions. Schuchertella differs from GoniarinaCooper and Grant, 1969 from the Permian of Texas by its less conical ventral valve, its less elongated interarea and its shorter and thinner dentifers; it differs from StreptorhynchusKing, 1850 from the Permian–Carboniferous of Germany because the latter has a more conical ventral valve, a shorter cardinal margin and finer costellae increasing in number by bifurcation and not by intercalation, like in Schuchertella; it differs from OmboniaCaneva, 1906 from the Lopingian of the Southern Alps, Italy because it lacks a ventral spondylium. Schuchertella has a long stratigraphic distribution, from the Late Devonian to the Late Permian.

Schuchertella semiplana (Waagen, 1883) (Fig. 13 i–l; fig. 15 l)

1883 Orthotetes semiplana Waagen: p. 608; pl. 55, figs 1–2.

1927 Schuchertella cf. S. semiplana (Waagen) – Chao: p. 107; pl. 1, fig. 4.

1936 Schuchertella cf. S. semiplana (Waagen) – Grabau: p. 90; pl. 8, fig. 5.

1944 Streptorhynchus (Schuchertella) purdoni (Waagen) – Reed: pl. 2, figs 14–15.

1964 Schuchertella cf. S. semiplana (Waagen) – Wang et al.: p. 209; pl. 30, figs 18–19.

1965b Derbyia altestriata (Waagen) – Fantini Sestini: p. 38; pl. 3, fig. 7.

1980 Schuchertella semiplana (Waagen) – Li et al.: p. 332; pl. 158, figs 6–7.

2010 Schuchertella semiplana (Waagen) – Angiolini and Carabelli: p. 71; pl. 3, fig. 7; pl. 4, fig. 13.

Material: Five articulated specimens: MPUM 10818 (IR648A-72; IR650C-1), MPUM 10819 (IR648A-126), MPUM 10820 (IR650B-1-2); one dorsal valve: MPUM 10821 (IR650B-3).

Figured material: Three articulated specimens: MPUM 10819 (IR648A-126), MPUM 10820 (IR650B-1-2).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium sized, biconvex shell with subrectangular outline; maximum width at midvalve, ranging between 20.7 and 26.8 mm, length ranging between 19.7 and 20.9 mm; cardinal margin straight; anterior commissure rectimarginate. Ventral valve conical, slightly convex, quite flat; umbo not recurved; interarea apsacline, wide, not very high, flat or slightly concave; pseudodeltidium convex and triangular. Dorsal valve slightly convex, quite flat; weak median sulcus, widening anteriorly. Ornamentation on both valves of regular costellae, numbering 8–10 per 5 mm at the anterior commissure, increasing their number by intercalation of finer costellae; intercostal spaces 0.8–1 mm wide; weak growth lines irregularly spaced anteriorly. Interior of ventral valve without dental plates.

Discussion:Schuchertella semiplana differs from Schuchertella fushuiensisChen and Liao, 2007 from the upper Changhsingian of China by its smaller size, its umbo not projected backward and its finer costellae; it differs from Schuchertella subvexaCooper and Grant, 1974 from the Permian of Texas because the latter has a deformed umbo, a high and asymmetrical interarea and coarser costellae; it differs from Schuchertella cooperiGrant, 1976 from the Cisuralian of Thailand by its less convex valves and its weaker sulcus; it differs from Schuchertella tapina Grant, 1993 from the Guadalupian of Chios, Greece by its less conical ventral valve and its lower interarea; finally it differs from Schuchertella bassaGrant, 1995 from the Lopingian of Greece because the latter has a deformed umbo and a greater number of costellae. The specimen described as Derbyia altestriata Waagen, 1884 by Fantini Sestini (1965b) is in fact Schuchertella semiplana.

Stratigraphic and geographic occurrence:Schuchertella semiplana has been found in the Lopingian Chhidru Formation of Khisor Range, Pakistan (Waagen, 1883), in the Permian Chihsia Limestone of China (Chao, 1927), in the Guadalupian Ruteh Limestone of North Iran (Fantini Sestini, 1965b) and in the Lopingian Nesen Formation of North Iran (Angiolini and Carabelli, 2010).

Class RHYNCHONELLATA Williams et al., 1996

Order ORTHIDA Schuchert and Cooper, 1932

Suborder DALMANELLIDINA Moore, 1952

Superfamily ENTELETOIDEA Waagen, 1884

Family SCHIzOPHORIIDAE Schuchert and LeVene, 1929

Genus Kotlaia Grant, 1993

Type-species:Kotlaia capillosa Grant, 1993 from the Lopingian of Khisor Range, Pakistan.

Remarks:Kotlaia differs from OrthotichiaHall and Clarke, 1892 from the Carboniferous of Brazil by its smaller size, its equally convex valves, its slightly sulcate anterior commissure, its straight and divergent socket plates, its stronger dental plates and its longer median septum, which can reach the anterior commissure; it differs from AcosarinaCooper and Grant, 1969 from the Cisuralian of Texas by its numerous tubular costellae on both valves and its longer median septum. According to Angiolini et al., 2005Acosarina, Orthotichia and Kotlaia are difficult to distinguish because morphologically they are very similar; however it seems more appropriate to include the greater part of the Guadalupian Arabian-Asian specimens of Orthotichia in the genus Kotlaia.

Kotlaia bistriata (Reed, 1944) (Fig. 13 m–u)

1944 Orthotichia bistriata Reed: p. 10; pl. 1, figs 5, 5a, 5b.

1965b Orthotichia indica (Waagen) – Fantini Sestini: p. 31; pl. 3, figs 1 a–d, 2.

1999 Orthotichia sp. cf. O. bistriata (Reed) – Angiolini and Bucher: p. 690; figs 17.1–17.9, tab. 12.

Material: Four articulated specimens: MPUM 10822 (IR123-59-68), MPUM 10823 (IR123-64), MPUM 10824 (IR448bis-5); thirty-one ventral valves: MPUM 10825 (IR48-46-62, IR51-15-16-29, IR61-33-39, IR123-1-9-10-16-17-20-21-27-31-33-34-36-37-40-41-48-60-72-80-86, IR126-2, IR648A-61-127), MPUM 10826 (IR123-58); thirty-two dorsal valves: MPUM 10827 (IR48-74, IR51-13-14-37, IR61-13-37-40, IR123-6-14-19-25-29-35-39-42-45-46-47-49-50-51-52-54-55-61-62-77, IR126-3), MPUM 10828 (IR123-2), MPUM 10829 (IR123-11), MPUM 10830 (IR123-44), MPUM 10831 (IR123-79); fragments: MPUM 10832 (IR48-70-76, IR61-31-36-42-43-54-55-59, IR123-3-7-13-15-18-22-26-28-32-56-83, IR125-2, IR126-7).

Figured material: Two articulated specimens: MPUM 10823 (IR123-64), MPUM 10824 (IR448bis-5); one ventral valve: MPUM 10826 (IR123-58); four dorsal valves: MPUM 10828 (IR123-2), MPUM 10829 (IR123-11), MPUM 10830 (IR123-44), MPUM 10831 (IR123-79).

Occurrence: North Iran, Ruteh Limestone, Dorud section 36°00′18.3″N, 51°29′01.6″E; Dorud section loose block; Ruteh section, 35°58′38.3″N, 51°32′28.9″E; Khouban Pass section, 36°01′50″N, 51°25′53.8″E; Mangol Restaurant 1 section, 36°14′58.2″N, 55°22′05.1″E; Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium to small sized, biconvex shell with slightly transverse outline; maximum width at midvalve ranging between 9.3 and 20 mm, length ranging between 8.2 and 17.3 mm; cardinal margin short and straight; anterior commissure slightly sulcate to rectimarginate. Ventral valve convex, slightly swollen, with subrectangular to subtriangular outline; umbo slightly recurved and slightly prominent on the hinge. Dorsal valve more convex than the ventral valve; weak sulcus starting near the umbo and widening, but not deepening, anteriorly. Ornamentation on both valves of interrupted, tubular costellae, numbering 11–13 per 5 mm at the anterior commissure, starting from the umbo; 2–3 finer costellae occur in the intercostal spaces, especially in the dorsal valve; small circular holes, determined by the opening of tubules forming the costellae; concentric lamellae irregularly spaced. Interior of ventral valve with a median septum that reaches and sometimes passes the midlength of the valve.

Discussion:Kotlaia bistriata differs from Kotlaia waterhousei (Grant, 1976) from the Guadalupian of Thailand by its larger size and its finer ornamentation; it differs from Kotlaia capillosa Grant, 1993 by its tubular, interrupted costellae, its wider interspaces and by its shorter median septum that in Kotlaia capillosa reaches the anterior commissure, whereas in Kotlaia bistriata reaches the midlength of the valve; it differs from Kotlaia aethopa Grant, 1993 from the Guadalupian of Chios, Greece, by its fewer costellae, its wider interspaces, its finer costellae in the intercostal spaces and its shorter median septum.

Stratigraphic and geographic occurrence:Kotlaia bistriata has been found in the Guadalupian Amb Formation of the Salt Range, Pakistan (Reed, 1944), in the Guadalupian Ruteh Limestone of North Iran (Fantini Sestini, 1965b) and in the Wordian Khuff Formation of Oman (Angiolini and Bucher, 1999).

Order ATHYRIDIDA Boucot, Johnson and Staton, 1964

Suborder ATHYRIDIDINA Boucot, Johnson and Staton, 1964

Superfamily ATHYRIDOIDEA Davidson, 1881

Family ATHYRIDIDAE Davidson, 1881

Subfamily SPIRIGERELLINAE Grunt, 1965

Genus Spirigerella Waagen, 1883

Type-species:Spirigerella derbyi Waagen, 1883 from the Lopingian of the Salt Range, Pakistan.

Remarks:Spirigerella differs from SeptospirigerellaGrunt, 1965 from the Lopingian of Transcaucasia by its ventral sulcus, its dorsal fold, its more recurved umbo and by its strongly developed cardinal plates; it differs from PosicomtaGrunt, 1986 from the Lopingian of Tajikistan by its ventral sulcus and its more evident dorsal fold; it differs from JuxathyrisLiang, 1990 from the Guadalupian and the Lopingian of South China because the latter has socket plates replaced by high and wide processes.

?Spirigerellasp. ind. (Fig. 14 a)

Material: One figured ventral valve: MPUM 10833 (IR123-89).

Occurrence: North Iran, Ruteh Limestone, Khouban Pass section, 36°01′50″N, 51°25′53.8″E.

Description: Small sized, convex ventral valve with suboval outline; maximum width at midvalve: 10.8 mm, corresponding length: 11 mm; recurved umbo; sulcus starting near the umbo, widening and deepening anteriorly; anterior commissure uniplicate. Ornamentation of irregularly spaced growth lamellae, more evident anteriorly, where they follow the plication of the shell.

Discussion: This specimen probably belongs to the genus Spirigerella; it has a convex ventral valve, a strongly recurved umbo, a ventral sulcus and ornamentation similar to that of Spirigerella. However, the diagnostic characters used to distinguish Spirigerella from other genera are the internal features which in this specimen are not observable, so the assignment is not certain. It differs from Spirigerella derbyi Waagen, 1883 from the Guadalupian of the Salt Range, Pakistan by its smaller size and its less marked ornamentation; it differs from Spirigerella minuta Waagen, 1883 from the Guadalupian of the Salt Range, Pakistan by its less elongated outline.

Order SPIRIFERIDA Waagen, 1883

Suborder SPIRIFERIDINA Waagen, 1883

Superfamily MARTINIOIDEA Waagen, 1883

Family MARTINIIDAE Waagen, 1883

Subfamily MARTINIINAE Waagen, 1883

Genus MartiniaM’Coy, 1844

Type-species:Spirifer glaber Sowerby, 1820 from the Early Carboniferous of England.

Remarks:Martinia differs from SquamulariaGemmellaro, 1899 from the Guadalupian of Sicily, Italy because it has a uniplicate anterior commissure and it lacks regular concentric ornamentation and spines; it differs from Martiniopsis Waagen, 1883 from the Lopingian of Pakistan because it lacks a median septum and dental plates; it differs from NotospiriferHarrington, 1955 and from IngelarellaCampbell, 1959 from the Permian of Australia because it lacks costae and dental plates; finally it differs from EllaFredericks, 1918 from the Cisuralian of Russia because it lacks costae, dental plates and a median septum.

Martinia bassa n. sp. (Fig. 14 b–i)

1965b Cleiothyridina cf. C. capillata (Waagen) - Fantini Sestini: p. 66; pl. 7, fig. 4.

Holotype: MPUM 10835 (IR48-51).

Derivation of the name:bassa from the latin low to indicate its low umbo.

Material: Six articulated specimens: MPUM 10834 (IR48-45), MPUM 10835 (IR48-51), MPUM 10836 (IR123-4) MPUM 10837 (IR123-71-93), MPUM 10838 (IR123-90); six ventral valves: MPUM 10839 (IR48-5-16-78, IR60-1, IR648A-49), MPUM 10840 (IR61-6); fragments: MPUM 10841 (IR48-67-73, IR51-7-8-9-18-21-22-23-34, IR59-1-4, IR61-1-9-16-18-24-25-26-28-38-41-57-60, IR123-23-24).

Figured material: Four articulated specimens: MPUM 10834 (IR48-45), MPUM 10835 (IR48-51), MPUM 10836 (IR123-4), MPUM 10838 (IR123-90); one ventral valve: MPUM 10840 (IR61-6).

Occurrence: North Iran, Ruteh Limestone, Dorud section 36°00′18.3″N, 51°29′01.6″E; Dorud section loose block; Ruteh section, 35°58′38.3″N, 51°32′28.9″E; Khouban Pass section, 36°01′50″N, 51°25′53.8″E; Shirinabad section, 36°53′46″N, 55°09′30″E.

Diagnosis: species of Martinia characterized by a low umbo and an indistinct, poorly defined interarea.

Description: Medium to small sized, biconvex shell with subcircular outline; maximum width ranging between 11.2 and 13.7 mm, length ranging between 11.1 and 14.4 mm; cardinal margin short; anterior commissure uniplicate. Ventral valve convex, slightly swollen; curved, low umbo, close to the dorsal one; indistinct interarea; sulcus starting at midvalve, widening anteriorly. Dorsal valve more convex than the ventral valve. Ornamentation of growth lines irregularly spaced; anteriorly they follow the plication of the shell; shell surface finely pitted. Interior of dorsal valve with a muscle field divided by a short myophragm; radial vascular impressions.

Discussion: The distinctive characters of Martinia bassa n. sp. are a low umbo and consequently indistinct poorly defined interarea, characters not observable in other species of Martinia; for these characters it differs from Martinia pusilla Gemmellaro, 1887 from the Guadalupian of Sicily, Italy, from Martinia orbicularisGemmellaro, 1899 from the Guadalupian of Sicily, Italy, from Martinia semiplana Waagen, 1883 and from Martinia elongata Waagen, 1883 from the Guadalupian of the Salt Range, Pakistan. The specimens described as Cleiothyridina cf. C. capillata (Waagen, 1883) by Fantini Sestini (1965b) belong to Martinia bassa n. sp.

Suborder DELTHYRIDINA Ivanova, 1972

Superfamily RETICULAROIDEA Waagen, 1883

Family ELYTHIDAE Fredericks, 1924

Subfamily PHRICODOTHYRIDINAE Caster, 1939

Genus SquamulariaGemmellaro, 1899

Type-species:Squamularia rotundataGemmellaro, 1899 from the Guadalupian of Sicily, Italy.

Remarks:Squamularia is very similar to PermophricodothyrisPavlova, 1965 from the Lopingian of Transcaucasia, but it differs mainly by the direction of the axes of the spiralia; in Squamularia they are laterally directed, resulting in a transverse outline with maximum width of the shell placed at midlength; furthermore, the number of coils is about eight and the spiralia fill the entire shell cavity; Permophricodothyris, on the other hand, has the axes of the spiralia directed posterolaterally, with a smaller diameter of the cone base of the spiralia in relation to the length of the axis, a number of coils up to 28 and with the spiralia which do not fill the entire cavity of the shell; another difference between the two genera is relative to the crural plates, that in Squamularia diverge from the dorsal cardinal margin and later converge toward a median line, whereas in Permophricodothyris the crura are straight or slightly convergent towards the median line. Verna and Angiolini in Verna et al. (2011) have shown that the type-material of Squamularia rotundataGemmellaro, 1899 (Museum G. Gemmellaro of Palermo, Italy) has biramous spines and thus should be assigned to the Family Elythidae Fredericks, 1924, and not to the Family Reticulariidae Waagen, 1883 (Carter and Gourvennec in Williams et al., 2006).

Squamularia sp. A (Fig. 14 j, k)

1965b Neophricodothyris asiatica (Chao) - Fantini Sestini: p. 63.

Material: One figured articulated specimen: MPUM 10842 (IR650-1); one ventral valve: MPUM 10843 (IR123-74); fragment: MPUM 10844 (IR638-9).

Occurrence: North Iran, Ruteh Limestone, Khouban Pass section, 36°01′50″N, 51°25′53.8″E; Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Small to medium sized, biconvex shell with slightly transverse outline. Maximum width at midvalve: 18.5 mm, corresponding length: 16.9 mm; anterior commissure slightly sulcate. Ventral valve convex with subtriangular outline; umbo high, narrow, hooked and strongly curved on the hinge; wide interarea; very shallow sulcus starting at midvalve. Dorsal valve less convex than the ventral valve, with elliptical outline; umbo slightly projected over the hinge. Ornamentation of both valves consisting of concentric lamellae, closer near the umbo, more spaced anteriorly; tubercles on the anterior slope of the lamellae; spines in the interspaces between the lamellae. Interior of dorsal valve with traces of laterally directed spiralia.

Discussion: The Iranian specimens have been assigned to the genus Squamularia for their transverse outline, their ornamentation of growth lamellae bearing small spines, and for the presence of laterally directed spiralia; they differ from Squamularia formillaXu and Grant, 1994 from the Lopingian of China by their higher and more prominent umbo, very distinct from the rest of the valve, and by their fewer and more spaced lamellae; they are similar to ?Squamularia sp. ind. from the Guadalupian of Karakorum, Pakistan described by Angiolini (2001); they are also similar to Squamularia marcouxi Verna and Angiolini in Verna et al. (2011) from the Guadalupian of Turkey for the outline, but they differ by the presence of a high hooked umbo. The Iranian specimens have characteristic features, not observed in any other species of Squamularia, but the scarcity of material does not allow the erection of a new species. The specimens described as Neophricodothyris asiatica (Chao, 1929) by Fantini Sestini (1965b) are conspecific with Squamularia sp. A.

Squamularia sp. B (Fig. 14 l–q; Fig. 15 m, n)

Material: Five articulated specimens: MPUM 10845 (IR48-47), MPUM 10846 (IR123-57), MPUM 10847 (IR123-92), MPUM 10848 (IR123-94), MPUM 10849 (IR123-95); three dorsal valves: MPUM 10850 (IR48-55, IR60-2, IR123-66); fragments: MPUM 10851 (IR61-21-22, IR123-5-38-91).

Figured material: Four articulated specimens: MPUM 10845 (IR48-47), MPUM 10847 (IR123-92), MPUM 10848 (IR123-94), MPUM 10849 (IR123-95).

Occurrence: North Iran, Ruteh Limestone, Dorud section 36°00′18.3″N, 51°29′01.6″E; Ruteh section, 35°58′38.3″N, 51°32′28.9″E; Khouban Pass section, 36°01′50″N, 51°25′53.8″E.

Description: Small sized, biconvex shell with subcircular outline; maximum width ranging between 7.2 and 10.4 mm, length ranging between 7.1 and 11.4 mm; anterior commissure rectimarginate. Ventral valve convex; umbo curved and slightly prominent on the hinge. Dorsal valve less convex than the ventral valve; umbo curved on the hinge. Ornamentation of both valves of irregular growth lamellae; small tubercles corresponding to the lamellae. Interior of dorsal valve with divergent crural plates; traces of laterally directed spiralia.

Discussion: The internal characters of the dorsal valve allow assignment of these specimens to the genus Squamularia and not to Permophricodothyris; they differ from Squamularia rotundataGemmellaro, 1899 from the Guadalupian of Sicily, Italy because of their smaller size, their lower convexity and because they lack a ventral sulcus; they differ from Squamularia sp. A by their subcircular outline, their smaller size, their lower convexity and their more numerous lamellae; the poor preservation of these specimens does not allow a specific attribution.

Genus PermophricodothyrisPavlova, 1965

Type-species:Permophricodothyris ovataPavlova, 1965 from the Lopingian of Caucasus.

Remarks: According to Pavlova (1965),Permophricodothyris is characterized by the presence of spiralia with posterolaterally directed axes of coil, by a microornamentation of double spine bases and by the absence of dental plates, adminicula and septum. According to Shi et al. (2002) 22.2% of the species of Permophricodothyris occur in the Guadalupian, with Permophricodothyris extensiformis (Chang, in Yang et al., 1977) representing the oldest form, and 77.8% is present in the Lopingian; this genus quickly diversifies in the Wuchiapingian, starts to decline in the Changhsingian and goes extinct at the Permian/Triassic boundary.

?Permophricodothyris sp. ind. (Fig. 14 r, s)

Material: Two ventral valves: MPUM 10852 (IR48-49), MPUM 10853 (IR48-58); one dorsal valve: MPUM 10854 (IR61-56); fragments: MPUM 10855 (IR48-17, IR51-36).

Figured material: One ventral valve: MPUM 10853 (IR48-58); one dorsal valve: MPUM 10854 (IR61-56).

Occurrence: North Iran, Ruteh Limestone, Dorud section 36°00′18.3″N, 51°29′01.6″E; Dorud section loose block; Ruteh section, 35°58′38.3″N, 51°32′28.9″E.

Description: Small sized, biconvex shell with suboval, elongated outline; width ranging between 8 and 11.6 mm, length ranging between 11.7 and 13.2 mm. Ventral valve convex, with the maximum convexity posteriorly; very weak sulcus starting at midvalve. Dorsal valve less convex than the ventral valve. Ornamentation of irregular concentric lamellae. Interior of dorsal valve with crural bases.

Discussion: These specimens are poorly preserved but they probably belong to the genus Permophricodotyhyris for their lamellose ornamentation and for their elongated outline, that may suggest the presence of posterolaterally directed spiralia.

Order SPIRIFERINIDA Ivanova, 1972

Suborder SPIRIFERINIDINA Ivanova, 1972

Superfamily PENNOSPIRIFERINOIDEA Dagys, 1972

Family RETICULARIINIDAE Waterhouse, 1975

Genus ReticulariinaFredericks, 1916

Type-species:Spirifer spinosusNorwood and Pratten, 1855 from the Pennsylvanian of Illinois, USA.

Remarks:Reticulariina differs from ParaspiriferinaReed, 1944 from the Guadalupian of India by its more transverse shell, its larger size, its weaker growth lamellae, its coarser punctae, its more marked plicae and because it lacks the jugum; it differs from CrenispiriferStehli, 1954 from the Cisuralian of Texas by its more rounded plicae and its fewer and coarser spines, from AltiplecusStehli, 1954 from the Cisuralian of Texas by its stronger plicae and its lower interarea and from CallispirinaCooper and Muir-Wood, 1951 from the Guadalupian of Pakistan because the latter has strongly convex valves, angular plicae and interspaces, and a microornamentation of growth lamellae with a row of short spines, bearing two rows of punctae; finally it differs from SpiriferellinaFredericks, 1924 from the Lopingian of Germany, by its more transverse outline, its larger spine bases and its rounded plicae.

Reticulariinasp. ind. (Fig. 14 t)

1965b Spiriferellina cristata (Schlotheim) – Fantini Sestini: p. 65.

Material: One figured ventral valve: MPUM 10856 (IR60-3).

Occurrence: North Iran, Ruteh Limestone, Ruteh section, 35°58′38.3″N, 51°32′28.9″E.

Description: Small sized, convex, slightly swollen ventral valve with transverse outline; width 16.4 mm, length not measured because of the incompleteness of the specimen; shell substance punctate. Cardinal extremities angular; pointed and high umbo; deep sulcus, starting from the umbo and widening anteriorly. Ornamentation of rounded plicae, numbering 6–7 on each side of the sulcus; interspaces (0.6 mm wide) wider than the plicae.

Discussion: This specimen does not belong to Spiriferellina mainly because of the presence of rounded plicae. It has been compared with some species from the Permian of Texas described by Cooper and Grant (1976): it differs from Reticulariina cerina and from Reticulariina subovata by its less transverse outline; it differs from Reticulariina craticula, from Reticulariina powwowensis, from Reticulariina welleri and from Reticulariina pusilla by its narrow plicae, which are also present in a greater number. The specimens described as Spiriferellina cristata (Schlotheim, 1816) by Fantini Sestini (1965b) are conspecific with the specimen under examination.

Order TEREBRATULIDA Waagen, 1883

Suborder TEREBRATULIDINA Waagen, 1883

Superfamily CRYPTONELLOIDEA Thomson, 1926

Family NOTOTHYRIDIDAE Licharew, 1960

Genus RostranterisGemmellaro, 1899

Type-species:Dielasma adrianenseGemmellaro, 1899 from the Guadalupian of Sicily, Italy.

Remarks:Rostranteris is very similar to Notothyris Waagen, 1882 from the Guadalupian of the Salt Range, Pakistan, but they differ mainly in the external features; Rostranteris has a plicate anterior commissure and generally a low number of plicae, whereas Notothyris has a rectimarginate or slightly sulcate anterior commissure and a high number of plicae. Furthermore, according to Smirnova (2007), Rostranteris differs from Notothyris in the crural bases located on the ventral side of the inner hinge plate, whereas in Notothyris they are located on the dorsal side of the inner hinge plate.

Rostranteris exile Gemmellaro, 1899 (Fig. 14 u)

1899 Rostranteris exile Gemmellaro: p. 243; tav. 25, fig. 63-70; tav. 27, fig. 60; tav. 30, fig. 42.

Material: One figured ventral valve: MPUM 10857 (IR659-1).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Small sized, convex ventral valve with elongated outline; width: 5.5 mm, length: 7.7 mm; recurved umbo; two plicae anteriorly, not reaching the midlength of the valve. Smooth valve.

Discussion:Rostranteris exile differs from Rostranteris mediterraneumGemmellaro, 1899 from the Guadalupian of Sicily, Italy because the latter is thinner and it has less evident plicae; it differs from Rostranteris adrianense by its more elongated outline and its longer and more recurved umbo and from Rostranteris inflatumGemmellaro, 1899 from the Guadalupian of Sicily, Italy by its more elongated outline, its less convex ventral valve and its fewer plicae.

Stratigraphic and geographic occurrence:Rostranteris exile has been found in the Guadalupian of Sosio Valley, Sicily, Italy (Gemmellaro, 1899).

Rostranteris gemmellaroiSmirnova and Grunt, 2002 (Fig. 14 v, w)

2002 Rostranteris gemmellaroi Smirnova and Grunt: p. 484; figs 4 a–d.

Material: One figured articulated specimen: MPUM 10858 (IR659-6).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Small sized, biconvex shell with subcircular to suboval outline; width: 6.3 mm, length: 7 mm; curved cardinal margin; anterior commissure biplicate. Ventral valve strongly convex; umbo high, narrow and hooked; small elliptical foramen; a strong plica starts from the umbo and bifurcates at midvalve, forming two distinct plicae, which are separated by a narrow and not very deep sulcus; two minor and indistinct plicae at the sides of the major plicae. Dorsal valve less convex than the ventral valve; two major plicae starting from the umbo, with one minor plicae between them anteriorly; two minor and indistinct plicae at the sides of the major plicae. Smooth valves.

Discussion: This specimen is probably a juvenile specimen or an adult specimen, which has interrupted its growth and has kept a small size; it differs from Rostranteris bukharica (Tschernyschew, 1914) from the Permian of Pamir by its larger size, its less convex valves and its less recurved umbo; it differs from Rostranteris ovaleformisSmirnova, 2001 and Rostranteris charymdarensisSmirnova and Grunt, 2002 from the Guadalupian of Pamir by its larger apical angle, its less curved cardinal margin and its less evident plicae; finally it differs from Rostranteris inflatumGemmellaro, 1899 from the Guadalupian of Sicily, Italy by its higher and less recurved umbo and its more evident plicae.

Stratigraphic and geographic occurrence:Rostranteris gemmellaroi has been found in the Guadalupian Gundara Formation of Pamir (Smirnova and Grunt, 2002).

Superfamily DIELASMATOIDEA Schuchert, 1913

Family DIELASMATIDAE Schuchert, 1913

Subfamily DIELASMATINAE Schuchert, 1913

Genus DielasmaKing, 1859

Type-species:Terebratulites elongatusVon Schlotheim, 1816 from the Guadalupian of Germany.

Remarks:Dielasma differs from Dielasmina Waagen, 1882 from the Guadalupian and the Lopingian of the Salt Range, Pakistan because the latter has a geniculated dorsal valve, a well developed peduncular collar and the outer cardinal plates converging medianly to form a septalium; it differs from PlectelasmaCooper and Grant, 1969 from the Guadalupian of Texas and from WhitspakiaStehli, 1964 from the Permian of the Salt Range, Pakistan by its uniplicate anterior commissure and because it lacks plicae; it differs from AneuthelasmaCooper and Grant, 1976 from the Permian of Texas and from Hemiptychina Waagen, 1882 from the Permian of the Salt Range, Pakistan by the occurrence of dental plates.

Dielasma sp. ind. (Fig. 14 x, y; Fig. 15 o)

Material: Two figured articulated specimens: MPUM 10859 (IR647bis-2), MPUM 10860 (IR648A-129); fragment: MPUM 10861 (IR649-15).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Small sized, biconvex shell with slightly elongated outline; maximum width at midvalve or posteriorly ranging between 12.1 and 13.9 mm, width: 14.2 mm; anterior commissure rectimarginate; shell substance punctate. Ventral valve convex posteriorly and flat anteriorly; umbo high, recurved, quite hooked and prominent on the hinge; concave palintrope; large, circular foramen. Dorsal valve convex posteriorly and flat anteriorly; umbo prominent on the hinge. Smooth valves. Interior of ventral valve with dental plates. Interior of dorsal valve with two short hinge plates, closely set on the valve floor.

Discussion: The Iranian specimens belong to the genus Dielasma by their external features and by the presence of dental plates and convergent hinge plates; however they are poorly preserved, so it is not possible to give them a specific determination. They differ from Dielasma minor Waagen, 1882 from the Guadalupian of the Salt Range, Pakistan by their anterior flattening and their higher umbo; they differ from Dielasma pictileCooper and Grant, 1976 from the Permian of Texas because the latter has a emarginate anterior commissure and a shallow, narrow ventral sulcus; finally they differ from Dielasma subcirculareCooper and Grant, 1976 from the Permian of Texas by their more elongated outline and their hooked umbo.

Family GILLEDIIDAE Campbell, 1965

Subfamily GILLEDIINAE Campbell, 1965

Genus Omanilasma Angiolini and zarbo, 2006

Type-species:Omanilasma husseinii Angiolini and Zarbo in Angiolini et al., 2006 from the Guadalupian of Oman.

Remarks:Omanilasma is very similar to DielasmaKing, 1859 from the Guadalupian of Germany but it differs because it lacks dental plates in the ventral valve; in fact it is characterized by the occurrence of reduced dental flanges supporting the teeth but not extending to the valve floor. This genus was first attributed to the family Dielasmatidae Schuchert, 1913, but the genera present in this family have dental adminicula, absent in Omanilasma; for this reason Omanilasma is here moved to the family Gillediidae Campbell, 1965. The specimens described as Dielasma grabauiFantini Sestini, 1965b and Dielasma itaitubense (Derby, 1874) by Fantini Sestini (1965b) from the Guadalupian Ruteh Limestone, North Iran probably belong to the genus Omanilasma because they lack dental plates.

Omanilasma aff. O. husseinii Angiolini and Zarbo, 2006 (Fig. 14 z–cc; Fig. 15 p–r)

1965b Dielasma grabaui Fantini Sestini: p. 72; pl. 6 figs 6 a–c; text-fg. 5

Material: Four articulated specimens: MPUM 10862 (IR48-77, IR648A-68), MPUM 10863 (IR645-13), MPUM 10864 (IR1111bis-1); two ventral valves: MPUM 10865 (IR48-12, IR649-9); fragments: MPUM 10866 (IR123-75-81, IR647-7, IR648A-48, IR649-2-17-18-19).

Figured material: Two articulated specimens: MPUM 10863 (IR645-13), MPUM 10864 (IR1111bis-1).

Occurrence: North Iran, Ruteh Limestone, Dorud section 36°00′18.3″N, 51°29′01.6″E; Khouban Pass section, 36°01′50″N, 51°25′53.8″E; Shirinabad section, 36°53′46″N, 55°09′30″E; Ruteh Valley section, 35°58′35,2″N, 51°31′59″E.

Description: Medium to small sized, biconvex shell with elongated suboval outline; maximum width anteriorly, ranging between 9.6 and 14.9 mm, length ranging between 13.2 and 21.2 mm; anterior commissure rectimarginate to slightly parasulcate. Ventral valve convex; umbo high and recurved with a circular epithyrid foramen. Dorsal valve less convex than the ventral valve with the maximum convexity posteriorly. Smooth valves. Interior of ventral valve without dental plates. Interior of dorsal valve with hinge plates.

Discussion: These specimens have been assigned to the genus Omanilasma because they lack dental plates. They are similar to Omanilasma husseinii but they have a more convex dorsal valve and a more recurved dorsal umbonal region. They differ from Omanilasma desertica Angiolini and Zarbo, 2006 from the Guadalupian of Oman by their larger size and their less elongated outline. Finally, they differ from Dielasma itaitubense described by Fantini Sestini (1965b) by their smaller size and their less convex ventral valve.

Stratigraphic and geographic occurrence:Omanilasma husseinii has been found in the Guadalupian Ruteh Limestone of North Iran (Fantini Sestini, 1965b), in the Wordian Khuff Formation of Oman and in the Capitanian Midhnab Member Khuff Formation, of Saudi Arabia (Angiolini et al., 2006; Nicora et al., 2006).

Genus Bisolcatelasma n. gen.

Type-species: Bisolcatelasma iraniana n. sp. from the Ruteh Limestone of North Iran.

Derivation of the name:Bisolcatelasma because it is similar to Dielasma, but it has an evident sulcus on both valves.

Diagnosis: Gillediidae with an evident sulcus on both valves.

Remarks: The new genus is characterized by the occurrence of a thick shell, strongly convex valves, a deep sulcus on both valves and an emarginate anterior commissure. It is similar to Omanilasma Angiolini and Zarbo, 2006 from the Guadalupian of Oman for the internal features, but it differs by its more convex valves, its sulcus on both valves and its emarginate anterior commissure; it differs from PseudodielasmaBrill, 1940 from the Guadalupian of Texas because the latter has a paraplicate to biplicate anterior commissure and a dorsal sulcus delimited by two lateral plicae; it differs from LevenolasmaSmirnova and Grunt, 2003 from the Guadalupian of Tajikistan by its more convex ventral valve and its longer outer cardinal plates; it differs from DielasmaKing, 1859 from the Guadalupian of Germany by its sulcus on both valves and because it lacks dental plates.

Bisolcatelasma iraniana n. sp. (Fig. 15 a–f, s, t)

Holotype: MPUM 10870 (IR649-6).

Derivation of the name:iraniana from Iran, the place where the type-locality is placed.

Material: Eight articulated specimens: MPUM 10867 (IR649-3-7-10-12), MPUM 10868 (IR649-4), MPUM 10869 (IR649-5), MPUM 10870 (IR649-6), MPUM 10871 (IR649-11).

Figured material: Four articulated specimens: MPUM 10868 (IR649-4), MPUM 10869 (IR649-5), MPUM 10870 (IR649-6), MPUM 10871 (IR649-11).

Occurrence: North Iran, Ruteh Limestone, Shirinabad section, 36°53′46″N, 55°09′30″E.

Description: Medium sized, strongly biconvex and thick shell with elongated suboval outline; maximum width at midvalve or slightly anteriorly ranging between 14 and 20.6 mm, length ranging between 25.3 and 33.9 mm; anterior commissure emarginate; shell substance finely punctate. Ventral valve convex and swollen, with the maximum convexity in the umbonal region; recurved umbo, not very high with a quite large and circular foramen; deep and narrow sulcus starting near the umbo, deepening and slightly widening anteriorly, delimited by two lateral ridges. Dorsal valve slightly less convex than the ventral valve, with the maximum convexity in the umbonal region; umbo large and recurved; evident sulcus, less marked than that of the ventral valve, starting near the umbo and widening anteriorly. Smooth valve, except for some rare growth lines laterally. Interior of ventral valve with peduncolar collar and without dental plates. Interior of dorsal valve with outer hinge plates extending to the valve floor, continuing anteriorly up to one third of the length of the valve.

Discussion: The lack of dental plates allows assignment of this new genus and species to the family Gillediidae. The most important feature is the presence of a deep sulcus on both valves, a characteristic that is absent in other genera of this family. The two specimens described by Fantini Stestini (1965b) as Dielasma cf. D. plica (Kutorga, 1842) could belong to Bisolcatelasma iraniana n. sp., based on the shape of the ventral valve. However the lack of the dorsal valve does not allow certain identification.

ACKNOWLEDGEMENTS

Field work of L.A. in Iran was performed with assistance of the Geological Survey of Iran and financial support of the MEBE (Middle East Basins Evolution Programme) Programme and an Italian PRIN2004 Project. Giovanni Chiodi and Curzio Malinverno are thanked for technical support. Two anonymous reviewers are thanked for their suggestions. The authors wish to thank GeoArabia Designer Nestor “Niño” Buhay IV, for designing the paper for press.

ABOUT THE AUTHOR

Gaia Crippa received a Master’s degree in Earth Sciences from the University of Milan in 2010. The subject of her thesis was the systematic, biostratigraphic and palaeobiogeographic study of Guadalupian brachiopods from the Ruteh Limestone of Iran. For her BSc she studied the ultrastructure of Cisuralian brachiopods from Iran and Karakorum (Pakistan). She is currently doing researches on Permian brachiopods from Southeast Asia as well as continuing the study of the shell structure and its potential for palaeoclimatic reconstructions. gaiaegaia@alice.it

Lucia Angiolini is a Professor of Palaeontology at the Department of Earth Sciences, University of Milan, Italy. She received a PhD in Earth Sciences from the University of Milan in 1994, where she is now Associate Professor of Paleontology. Lucia has 15 years experience in Permian brachiopods from the Peri-Gondwana region and the Cimmerian blocks from Turkey to the Himalayas through Oman, Iran and Karakorum. Her research interests include, besides pure taxonomy, quantitative biostratigraphy, palaeobiogeography based on multivariate analyses, and Permian correlation between Gondwanan and Tethyan realms. lucia.angiolini@unimi.it