A microproblematicum with calcaerous test, Tabasosphaera
pustulosa nov. gen., nov. sp., a hollow spherical microfossil
with pustule-like elements on the outer surface, is described
from Upper Triassic (Norian-Rhaetian) reef limestones exposed
near the town of Ali-Abad, south of Tabas (northeast Iran).
Tabasosphaera is an endobiotic organism living within the
cavities of other organisms, such as brachiopods, worm tubes,
or in sponge spongocoels. The systematic position of
Tabasosphaera, its interspecific association and the fossil
assemblage of which it makes part is discussed. Most probably
Tabasosphaera represents a foraminifer belonging to the group
U niv e rsit y of So uth Flo r id a Sc h ol a r C o mm o ns T a b a so s ph a e r a Pu s tulo s a N o v Ge n., N o v S P ., A M icr opr oble m a t ic um ( F or a mini fe r?) f r om the U pp e r T r i a s sic ( N or i a n-R h a et i a n ) R eef Limes t ones of N a y b a nd F or m a t ion ( NE I r a n ) B a b a S e no w b a r i-D a r ya n E n v i r o n m en t a l Sus t a i n a bi l it y P u b l ic a t io n s
STUDIA UNIVERSITATIS BABE -BOLYAI, GEOLOGIA, XLIX, 2, 2004, 85-94 TABASOSPHAERA PUSTULOSA NOV. GEN., NOV. SP., A MICROPROBLEMATICUM (FORAMINIFER?) FROM THE UPPER TRIASSIC (NORIAN-RHAETIAN) REEF LIMESTONES OF NAYBAND FORMATION (NE IRAN) BABA SENOWBARI-DARYAN 1 ABSTRACT. A microproblematicum with calcaerous test, Tabasosphaera pustulosa nov. gen., nov. sp., a hollow spherical microfos sil with pustule-like elements on the outer surface, is described from Upper Triassic (Norian-Rhaetian) reef limestones exposed near the town of Ali-Abad, sout h of Tabas (northeast Iran). Tabasosphaera is an endobiotic organism living within the cavities of other organisms, such as brachiopods, worm tubes, or in sponge spongocoels. The systematic position of Tabasosphaera its interspecific association and the fossil assemb lage of which it makes part is discussed. Most probably Tabasosphaera represents a foraminifer belonging to the group Lagenina. Key words : Tabasosphaera microproblematicum, Triassic, Norian, Nayband Formation, reef, Iran. INTRODUCTION Microproblematica are microscopic small organisms whose systematic position within the animal or plant kindoms is uncertain or disputed. More than thirty such problematic or ganisms have been described from Triassic shallow water deposits, mostly reefs or reefal carbonates (Flgel 1972, Borza 1975, SenowbariDaryan 1984). Some microproblematica are important contributors to the construction of the reef framework (e.g. Radiomura cautica SENOWBARI-DARYAN & SCHFER or Lithocodium sp.), other are well stratigraphic or facies index fossils in Middle or Upper Triassic reefs and lagoonal carbonates (e.g. Ladinella porata OTT or Microtubus communis FLGEL). Problematic organisms of Upper Triassic reefs (Norian-Rhaetian age) known until 1981 are listed in Flgel (1981). The systematic position of some Triassic microproblematica is classified after the original description by different authors (Ebli & Schlagintweit 1989, Senowb ari-Daryan & Flgel 1996, SenowbariDaryan 1997, Senowbari-Daryan & Majidifard 2003). Different microproblematic organisms, such as Microtubus communis FLGEL, Radiomura cautica SENOWBARI-DARYAN & SCHFER, Lithocodium sp., Bacinella irregularis RADOICIC etc. occur also in Upper Triassic bioconstructions embedded within the Nayband Formation in centra l and northeast Iran. Additionally, the presently described Tabasosphaera pustulosa nov. gen., nov. sp. was found in two thin sections from the reef limestones ex posed near the town of Ali-Abad, south of Tabas (text-Fig. 1). 1 Institute of Paleontology, University of Erlange n-Nrnberg, Loewenichstr. 28, 91054 Erlangen, Germany. E-mail: email@example.com
BABA SENOWBARI-DARYAN 86 Fig. 1. Geographic map of locality (marked with asterisk) of Tabasosphaera pustulosa nov. gen., nov. sp.
TABASOSPHAERA PUSTULOSA NOV. GEN., NOV. SP., A MICROPROBLEMATICUM (FORAMINIFER?) 87 LOCALITY The siliciclastic-carbonate deposits of the Nayband Formation is one of the most widespread and important geological uni ts outcropping at numerous localities in central and northeast Iran (Seyed-Emami 2003). In both south and north flanks of Kuh-e Nayband, approximately 220 km s outh of the town Tabas, the Nayband Formation occurs in a widespread area (Brnnimann et al. 1971, Kluyver et al. 1983). Especially at the southern flank (ty pe locality of the Nayband Formation) it reaches a thickness of up to 3000 m (personal observation). In different stratigraphic levels of the Nayband Formation several coralor sponge-dominated bioconstructions of biohermaland biostromal -type were developed. Samples with Tabasosphaera come from a small sponge-dominated reef located approximately 6.5 km northwest of the small town of Ali-Abad, on the right side of the road from Ali-Abad to Ab-Boneh (text-Fig. 1). This reef yielded a high diversity of invertebrates, especially coralline sponges of the Sphinctozoida, Inozoida and Chaetetida type (including Spongiomorph ida), corals, etc. Within the marly sediments in this locality a variety of othe r reef building organisms, such as solitary and colonial corals, and reef dwellers, like gastropods, bivalves, brachiopods, etc. are very abundant. The gastropods of this locality are described by Ntzel & SenowbariDaryan (1999) and the bivalves by Hautma mm (2001). The description of sponges is in preparation. Tabasosphaera pustulosa nov. gen., nov. sp., with several specimens, was found in two thin sections (AB6 and AB7) coll ected from this locality. It may also occur in bioconstructions of other loca lities within the Nayband Formation. PALEONTOLOGY Incertae sedis Tabasosphaera nov. gen. Derivatio nominis : From the town Tabas (the closest large town to the type locality) and the spherical shape of the microfossil. Diagnosis : Hollow spherical to egg-shaped test of approximately 1 mm in diameter with numerous pustule-like protuberances on the outer surface. Thin wall, originally composed of aragonite or calcite, but pr esently preserved as calcite. Interior of the test is usually filled with calcite cement. Type species : Tabasosphaera pustulosa nov. sp. Tabasosphaera pustulosa nov. sp. (pl. I, figs. 1-3, pl. II, figs. 1-4, text-fig. 2) Derivatio nominis : Pustula (lat.= pimple). Accord ing to pimple-like proturberances on the test surface. Holotype : Designated as holotype is the specimen illustrated in pl. I, fig. 1/1. Contrary to paratypes, whose interior is filled with calcite cement, the interior of the holotype is filled with micritic sediment exhibiting the thin wall of the test. Paratypes : Except holotype all specimens figured in pl. I and pl. II.
BABA SENOWBARI-DARYAN 88 Locus typicus : At the noth flank of Kuh-e Nayband, small reef located about 6.5 km NW of the small town of Ali-Abad (text-fig. 1). Stratum typicum: Upper Triassic, most probably Rhaetian. Diagnosis : See diagnosis of the genus. Material : Several specimens in thin section AB6 and AB7 (Senowbari-Daryan: Triassic Iran). Depository : Institute of Paleontology, Universi ty of Erlangen (Senowbari-Daryan, Triassic Iran) Fig. 2. Reconstruction of Tabasosphaera pustulosa nov. gen., nov. sp. DESCRIPTION The interior of all specimens except the holotype (pl. I, fig. 1/1) are filled with secondary calcite cement. The diameter of this spherical to egg-shaped (oval in thin section: see pl. I, fig, 3) microfossil varies between 0.6 mm and 1.2 mm (tab. 1). The smaller specimens could be marginal sections of larger specimens. The dimensions of some specimens are given in tab. 1. The holotype (pl. I, fig.1/1) has a diameter of 0.64 by 0.8 mm and is filled with micritic sediment, showing the thin wall of the test. The wall (approximately 0.02 mm) appears light in transmitted light indicating the primary aragonite or calcite (now calcite) mineralogy of the test. The outer surface of all specimens bear numerous pustule-like protuberances with a length of 0.6-0.1 mm. One proturberance in the holotype shows a pore piercing the proturberances. Because of intense recrystalization in all other specimens this character could not be recogn ized. The small specimen illustrated in pl. II, fig. 4 exhibits a neck-like elongation, but this could not be observed in other specimens. Therefore, the presence of a neck is not confirmed.
TABASOSPHAERA PUSTULOSA NOV. GEN., NOV. SP., A MICROPROBLEMATICUM (FORAMINIFER?) 89 Tabasosphaera pustulata was found in reef facies within the interior of other organisms, such as brachiopod shells (Pl. I, figs. 2-3), spongocoel of pharetronid sponges (pl. I, figs. 1, 4), chambers of sphinctozoid sponges (pl. I, fig. 1, pl. II, fig. 2) or in worm tubes (pl. II, fig. 3). No specim ens were found in the surrounding micritic sediment. A reconstruction of Tabasosphaera pustulata is given in text-fig.2. ORGANISM ASSOCIATION Tabasosphaera pustulata nov. gen., nov. sp. is associated with sponges (Sphinctozoida, Inozoida, Chaetetida, Spongiomorphida), abundant worm tubes, brachiopod shells and the microproblematicum Microtubus communis FLGEL. The space between the organisms is filled with micritic or with microsparitic sediment. All facies characters and the fossil assemblage indicate a reef rock deposited in low water movement below the current wave. DISCUSSION All specimens of Tabasosphaera pustulosa where found within the cavities of organisms (spongocoel or chambers of s ponges, brachiopods) representing the endobiotic and maybe cryptic lifestyle of th is microorganism. Regarding the systematic position of this spherical or egg-shaped microfossil, the following microorganisms may be considered: radiolarians, ostracods, calcispheres and foraminifers. Radiolarians : The mineralogy of skeleton (calcareous), the endobiontic lifestyle and the facies type do not favour the interpretation of Tabasosphaera pustulosa as a radiolarian. Ostracods: Ostracods are relatively abundant in micritic sediments or in cavities between or within the organisms in Triassic reefs. Sections through an ostracod shell may appear as circular or oval in thin section. Also ostracod shells may have puslute-like proturberances on the shell surf ace. However, because of the absence of connected shells, the ostracod assignation are out of the question. Also the pore-pierced pustules are not a typical feature for ostracods. Calcispheres : Calcispheres are calcitic spheres, ranging in size from less than 0.1 to 0.5 mm; thickness of shells varies from 3 to more than 200 microns. (Hntzschel 1975: 155). The systematic posi tion of calcispheres as foraminifera, acritarchs, planktonic alage or as cysts of algae is disputed. Because of its endobiontic lifestyle, the large dimensions of the test and the thin wall, Tabasosphaera pustulosa can hardly be regarded as calcispheres. A comparison with acritarchs is also out of the question. Foraminifers : The shape and dimension of the test, the test mineralogy (calcareous) and the perforated protur berances on the test wall allowed an interpretation of Tabasosphaera pustulosa in favour of foraminifers. Also the reefal facies type and lifestyle of Tabasosphaera pustulosa is consistent with this interpretation. As a foraminifer it can be regarded as a monochambered species, because no proloculus is observed. Mo rphologically indentical monochambered foraminifers are also knwon, especially from Paleozoic deposits. For example, the representatives of the family Parathura mminidae have a test characterized by a globular shape and pustule-like protuberances of the test wall with pores (apertur). An excellent example compared with Tabasosphaera pustulosa is the Paleozoic
BABA SENOWBARI-DARYAN 90 genus Paraturammina with the following diagnosis: Test globular, up to 0.45 mm in diameter; wall calcareous, granular, may appear striate in section; surface with numerous tubular protuberances, terminati ng in apertures. U. Silurian (Ludlovian) to L. Carboniferous (Tournaisian), Missi ssipian; Europe; Asia (Loeblich & Tappan 1988: 191). The main difference between the repres entatives of family Parathuramminidae and Tabasosphaera pustulosa is the microstructure of the wall (granular in Parathuramminidae, hyalin in Tabasosphaera ). Most probably Tabasosphaera pustulosa represents a foraminifer, which may be attributed to the group Lagenina. Table 1 Measurements of Tabasosphaera pustulosa nov. gen., nov. sp. DT) diameter of the test, LP) length of protuberances, NP) count number of proturberances, DP) diameter of protuberances at the base, H) Holotype. All measurements in mm. Thin section/ pl./fig. DT LP NP DP AB6/pl.2, fig.1 1. 00 x 1.20 0.06 4 0.06 AB7/pl. 1, fig.2 1. 10 x 1.20 0.06 2 0.10 AB7/pl. 1, fig. 2 1.00 x 1.04 0.06 8 0.08 AB7/pl. 1,fig. 3 0. 78 x 1.08 0.08 4 0.08 AB7/pl. 1, fig. 1(H) 0.64 x 0.8 0.06 3 0.08 AB7/pl.1, fig. 1 0. 7 x 0.7 0.10 3 1.20 AB7/pl. 2, fig. 4 1.24 x 1,40 0.08 8 0.08 Acknowlegments The investigation was carried out within the research project Palontologische Detailuntersuchungen in der Trias des Irans, SE 416/9 supported by the Deutsche Forschungsgemeinschaft (DFG). I would like to thank Dr. D. Garcia-Bellido Capdevila (Madrid) for English correction, Dr. M. Berncker for discussions, and Mrs. L. Neufert (both in University Erlangen-Nr nberg) for technical assistance. REFERENCES Borza, K., 1975, Mikroproblematika aus der oberen Trias der Westkarpaten, Geol. Zbornik Slov. Akad Vied 26: 199-236. Brnnimann, P., Zaninetti, L ., Borzorghnia, G., Dashti, R. & Moshtaghian, A., 1971, Lithostratigraphy and foraminifera of t he Upper Triassic Nayband Formation, Iran, Rev. Micropaleont ., 14 (5): 7-16. Ebli, O. & Schlagintweit, F., 1989, Muranella sphaerica Borza (Microproblematicum) from the Carnian Hallstatt Limestone of the Feuerk ogel (Austria/Northern Calcareous Alps): a nonskeletal precipitate.Mitt. Bayer. Staatssamml Palont. Histor. Geol ., 29: 53-60. Flgel, E., 1972, Mikroproblematika in Dnnschliffen von Trias-Kalken., Mitt. Ges. Geol. Bergbaustud sterreich, 21: 957-988. Flgel, E., 1981, Paleoecology and facies of Upper Triassic reefs in the Northern Calcar eous Alps.SEPM Special Publ ., 30: 291-359.
TABASOSPHAERA PUSTULOSA NOV. GEN., NOV. SP., A MICROPROBLEMATICUM (FORAMINIFER?) 91 Hntzschel, W., 1975, Trace fossils and Problematic a. In Moore, R. C. (ed.): Treatise on invertebrate Paleontology. Part W Miscellanea, Supplement 1, 269 p., University of Kansas Hautmann, M., 2001, Die Muschelfauna der Nayband-Formation (Obe rtrias, Nor-Rht) des stlichen Zentraliran. Beringeria 29: 1-181. Kulyver, H. M., Tirrul, R., Chan ce, P. N., Jones, G. W. & Meix ner, H. M., 1983, Explanatory text of the Naybandan Quadrangle ma p 1:250.000.Geol. Survey Iran Geol. Quadrangle J8, 143 p., Tehran. Loeblich, A. L. Jr. & Tappan, H., 1988, Foraminifera genera and their classification.2 vols., Van Nostrand Reinhold Co., New York. Ntzel, A. & Senowbari-Daryan, B., 1999, Gastropods from the Late Triassic (NorianRhaetian) Nayband Formation of central Iran, Beringeria 23 : 93-132. Senowbari-Daryan, B., 1984, Mikroproblematika aus den obertriadischen Riffkalken von Sizilien, Mnster. Forsch. Geol. Palont., 61 : 1-81. Senowbar-Daryan, B., 1997, Barbafera carnia Senowbari-Daryan, 1980: A Triassic wormtube, Facies 36:57-68. Senowbari-Daryan, B. & Flgel, E., 1996, A Problematic Fossil Revealed: Pycnoporidium ? eomesozoicum Flgel, 1972 (Late Triassic, Tethys).Not an Enigmatic Alga but a Strophomenid Brachiopod ( Gosaukammerella n. g.), Facies 34: 83-100. Senowbari-Daryan, B. & Majidifard, M. R., 2003, A Triassic Problematic Microfossil revealed: Probolocuspis espahkensis Brnnimann, Zaninetti, Moshtaghian and Huber 1974 is attributed to the Dasycladacean Algae, Facies 48: 107-114. Seyed-Emami, K. (2003): Triassic in Iran, Facies 48: 91-106. PLATE CAPTIONS Plate I Fig. 1-3: Tabasosphaera pustulosa nov. gen., nov. sp. from the Upper Triassic reef limestones of Nayband Formation near Ali-Abad (NE Iran). Fig. 1: Section through three specimens. The number indicates the holotype. The interior of the holotype is in contrary to all other speciemns filled with micritic sediment showing the thin wall and th ree proturberances. All three specimens are imbedded within the chamber interior of a sphinctozoid sponge. AB7, x22. Fig. 2: Three specimens in the interior of a brachiopod shell. All specimens are filled with calcite cement. One specimen shows up to 8 pustules. AB7, x20 Fig. 3: An oval (in section) specimen wi thin a brachiopod test. The pustule-like elements are well recognizable. AB7, x34. Plate II Fig. 1-4: Tabasosphaera pustulosa nov. gen., nov. sp. from the Upper Triassic reef limestones of Nayband Formation near Ali-Abad (NE Iran). Fig. 1: Specimen imbedded within the spo ngocoel of a pharetronid sponge. AB6, x22. Fig. 2: Two specimens within the chamber s of a sphinctozoid sponge. AB7, x32. Fig. 3: Two specimens which are imbedded within a serpulid worm tube or a brachiopod shell. AB7, x7.5. Fig. 4: Two specimens within the spongoc oel of a pharetronid sponge. The small specimen shows a neck-like extension of the test. AB7, x7.5
BABA SENOWBARI-DARYAN 92 Plate I
TABASOSPHAERA PUSTULOSA NOV. GEN., NOV. SP., A MICROPROBLEMATICUM (FORAMINIFER?) 93 Plate II