A new rugose coral species, Lithostrotion (Siphonodendron) hinensis is described in this paper. It was collected from the Carboniferous Hina limestone in Okayama Prefecture, Southwest Japan. Judging from the paleontological data, the age indicates probably Late Viaean, Early Carboniferous

Okimura, Yuji

Suzuki, Shigeyuki

Yamagiwa, Nobuo

A new rugose coral species, Lithostrotion (Siphonodendron) hinensis is described ID this paper. It was collected from the Carboniferous Hina limestone in Okayama Prefecture, Southwest Japan. Judging from the paleontological data, the age indicates probably Late Visean, Early Carboniferous

Nobuo Yamagiwa

Shigeyuki Suzuki

Yuji Okimura

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A New Species of Lithostrotion (Siphonodendron) (Rugosa) from the Hina Limestone, Okayama Prefecture, Southwest Japan

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OKAYAMA UniversityEarth Science Reports,Vol. 7, No. 1, 47-50, (2000)A New Species of Lithostrotion (Siphonodendron) (Rugosa) fromthe Hina Limestone, Okayama Prefecture, Southwest JapanNobuo YAMAGIWA*, Shigeyuki SUZUKI** and Yuji OKIMURA***A new rugose coral species, Lithostrotion (Siphonodendron) hinensis is describedID this paper. It was collected from the Carboniferous Hina limestone in OkayamaPrefecture, Southwest Japan. Judging from the paleontological data, the age indicatesprobably Late Visean, Early Carboniferous.Key words: Early Carboniferous, rugosa, Lithostrotion (Siphonodendron), HinaLimestone, Okayama. IntroductionA new rugose coral species, Lithostrotion(Siphonodendron) hinensis was collected by Mr.Reijiro Tsuboi from a boulder of Shigi River, whichflow throughout the Hina Limestone, Yosii-Cho,Shituki-Gun, Okayama Prefecture (Fig. I). Judgingfrom the sedimentary petrographical characters ofthe boulder containing the present specimen, therecan be not doubt that the boulder limestone wasderived from the lower part of the Hina Limestonecharacterized by the bryozoan and crinoidalbioclastic rudite, and biolithite with pelmicritematrices and fillings, respectively.The Hina Limestone IS an unstratifiedCarboniferous limestone mass overlying the basicrocks consisting mainly of the basaltic lava andtuff, which built up the submarine sea mount as wellas anthracolithic limestone Massifs in the ChugokuRegion (Yabe, 1958). From the lower part of thislimestone mass, two brachiopod faunas of lowerSpirifer sp. afT S. vesnosovae and upper Striatiftrastriata have been found by Hase and Yokoyama in1975, and their geological ages were correlated toEarly and Late Visean, respectively. Thiscorrelation based on the foraminiferal assemblagesof Endothyra and Eostafella-Millerella zonesidentified by one of the authors (Okimura).However, Kobayashi and Hamada (1978) whodescribed four new trilobites from lowest part of theHina Limestone indicate that the age may be rangeddown to the Toumaisian.Recently, Mizuno (1997) definedsystematically SIX conodont zones by thestratigraphical and paleontological close studies ofthe working face in the Kokan-Kogyo (Co.) quarry,and moreover four new and an undetermined species.•._-~ -----~---------_._----* Emeritus Prof. ofOsaka Kyoiku University,. 3-1-14-102 Shinkanaoka, Sakai, Osaka, 591·8021 Japan** Department of Earth SCiences, Faculty of SCience, Okayama University, Okayama, 700-8530 Japan*** Emeritus Prof. of Hiroshima University, 236-1 Ohtada, Kurose, Kamo, Hiroshima, 724-0611 Japan48 Nobuo Yamagiwa, Shigeyuki Suzuki and Yuji OkimuraFig. 1. Index map showing the sampling locality.like cut edges of tabulae. Minor septa relativelylong. Tabularial increase.Description: Corallum compound, fascicu-late and phaceloid. Corallites subcylindrical andsubparalleI. They separated from each other inmature stage. Increase tabularial type by Hill (1981)(PI. 1, figs. I-a, 5-b in this paper).In transverse section, corallites subcircularin outline, ranging from 3.5 to 4.5mm in diameterof tabulate corals have been described by Niko(1999) from the limestone blocks of Shigi River-bed.According to them, the geological age of the HinaLimestone corresponds with Early Visean to LateBashkirian.The present new species of rugose coral issimilar to the species described from the UpperVisean of Japan and China. Furthermore it isnoteworthily that such accompanying smallerforaminifers as Archaediscus spp., Endothyra spp.,Globivalvulina spp. and Tetrataxis spp. resemblethe Late Visean forms reported from the lower partof other limestone masses ("gigant-olistoliths") inthe Akiyoshi Terrane.11 • Systematic DescriptionFamily Lithostrotionidae d'Orbigy, 1852Subfamily Lithostrotioninae d'Orbigy, 1852Genus Lithostrotion Fleming, 1828Subgenus Siphonodendron M'Coy, 1849Lithostrotion (Siphonodendron) hinensis n. sp.(PI. I, figs. 1-7)Material: A single specimen, ESO-FOIOOl(Holotype). The specimen described herein ishoused in the Department of Earth Sciences,Faculty of Science, Okayama University.Diagnosis: Lithostrotion (Siphonodendron)with small sized corallites and narrowdissepimentarium having one row of concentricdissepiments. Tabularium wide, consisting of outerand inner tabulae. Outer tabulae mostly completeand steeply to gently ascending towards innertabulae. Inner tabulae complete and steeplyascending towards columella. Columella distinct; itunited with counter septum and rarely some majorsepta. Major septa 14 to 16 in number. The axialends ofmajor ones often terminated by the ring-132'I!Ia\yOkayama'-50km---~IA New Species of Lithostrotion (Siphonodendron) (Rugosa) 49in mature stage. Corallite wall moderately thick andcrenulated inside. Its fine structure fibro-normaltype by Kato (1963). Dissepimentarium narrow,usually consisting of one row of dissepiments.Dissepiments arranged concentrically. Tabulariumwide; sparsely concentric tabulae observed. Theaxial ends of major septa often terminated by thering-like cut edges of tabulae. Septa of two orders,major and minor in alternation; they straight orslightly sinuous. Septa moderately thick. Their finestructure diffuso-trabecular type by Kato (1963).Major septa 14 to 16 in number in mature stage.Most of them fall short of the center of corallite,as long as about 2/3 to 3/4 radius of corallite.Counter septum and rarely some major septa longerthan other major ones and united with columella.Minor septa about 1/2 to 2/3 length of major ones,but short or lacking in young stage. Columelladistinct, elongate fusiform to elliptical.In longitudinal section, dissepimentariumnarrow. It composed of vesicle-like dissepimentswith convex sides facing upwards as well as inwards.Dissepiments usually arranged III one row.Tabularium wide. Outer tabularium about 1/2 to 2/3radius of tabularium. Tabulae mostly complete andsteeply to gently ascending towards Innertabularium in typical sections (PI. 1, figs. 5-a, 6-7in this paper); they 3 to 4 in vertical distance of2mm. Clinotabellae rarely present. In Innertabu1arium, relatively densely constructed tabulaecomplete and steeply ascending towards columella,forming subtent-like structure in typical sections(PI. 1, figs. 5-a, 6-7 in this paper); they 5 to 7 invertical distance of 2mm. Columella moderatelythick and continuous. It straight or slightly sinuous.Discussion: The present form resemblesLithostrotion (Siphonodendron) asiatica minordescribed by Sato (1956, p. 248-249, PI. 9, figs. 1a-c) from the Upper Visean Tateishi Formation,Abukuma Massif, Northeast Japan in its similarcharacter of tabulae and dissepiments, number andlength of septa and form of columella. The formeris, however, clearly separable from the latter inhaving far larger corallites.It is also akin to the original speCImen ofLithostrotion (Siphonodendron) asiatica minordescribed by Minato (1943, p. 63-65, pI. 7, figs. 3-6) from the Upper Visean Kirin Formation, KirinProvince, China. However, the latter ISdistinguishable from the former in having farsmaller corallites and more densely constructedtabulae in longitudinal section. In addition, thelatter has gently ascending inner tabulae towardscolumella in longitudinal section.It IS also similar to Lithostrotion(Siphonodendron) pauciradiale described byMinato (1955, p. 74-76, PI. 3, figs. 3-4; Text-figs.6E-G) from the Upper Visean Onimaru Formation,Kitakarni Massif, Northeast Japan, but differs fromthe latter in having less numerous septa, long minorsepta and comparatively smaller corallites.It has some similarity with Lithostrotion( 'Siphonodendron' ) !asciculiseptatum Webb(1990, p. 98-100, Figs. 51F-G, 53, 57) from theVisean part of the Lower CarboniferousRockhampton Group, east-central Queensland,Australia. However, the latter can be distinguishedfrom the former in having numerous septa, shortminor septa and lateral increase. In addition, thelatter has numerous major septa united withcolumella.Etymology: The specific name IS derivedfrom the Hina Limestone in Okayama Prefecture,Southwest Japan.Ill. Acknowledgments50 Nobuo Yamagiwa, Shigeyuki Suzuki and Yuji OkimuraHere the authors express their heartythanks to Dr. Yoichi Ezaki (Osaka City University)for his kind advice and discussion. The authorsdeeply thank Mr. Reijirou Tsuboi for donation ofan important rugose coral specimen. Thanks arealso due to Prof. Fujio Masuda (Kyoto University)for his offer of references, and to Drs. KazuhikoIshii (Osaka Kyoiku University) and KazuyukiAkaishi (Osaka Kyoiku University) for their helpin the laboratory work.IV. ReferencesHase, A. and Yokoyama, M., 1975. Geological age andstructure of the Hina Limestone, OkayamaPrefecture, Southwest Japan. Jour. Sci. HiroshimaUniv., ser. C, 7: p. 167-182.Hill, D., 1981. Part F, Coelenterata. Supplement 1.Rugosa and Tabulata. In, Treatise on InvertebratePaleontology (eds. R C. Moore et al. ), p.I-726.Geol. Soc. America & Univ. Kansas, Boulder,Colorado & Laulence, Kansas.Kato, M., 1963. Fine skeletal structures in Rugosa. Jour.Fac. Sci., Hokkaido Univ., seT. 4, 11 (4): p. 571-630, pis. 1-3.Kobayashi, T. and Hamada, T., 1978. On some LowerCretaceous Trilobites from the Hina Limestone,Okayarna Prefecture, West Japan. Proc. japanAcad., SeT. B, 54: p. 5-9.Minato, M., 1943. Notes on some Lower Carboniferousfossils from the Kirin Formation in Mincheng,Panshih-hsien, Prov. Kirin, Manchoukou. Jour.Fac. Sci., Hokkaido Imp. Univ., seT. 4, 7 (1): p.59-66, pI. 7.Minato, M., 1955. Japanese Carboniferous and Permiancorals. Jour. Fac. Sci., Hokkaido Univ., seT. 4, 9(2): p. 1-202, pIs. 1-43.Mizuno, Y., 1997. Conodont faunas across the Mid-Carboniferous boundary in the Hina Limestone,Southwest Japan. Paleont. Res. 1, (4): p.237-259.Niko, S., 1999. Tabulate Corals from the CarboniferousHina Limestone, Okayama Prefecture. Bull. Nam.Sci. Mus., Tokyo, SeT. C, 25 (1, 2): p. 29-44.Sato, T., 1956. On the Tateishi Formation and itsCarboniferous coral fauna, in the northeastern partof the Abukuma Massif, Japan. Sci. Rep. TokyoKyoiku Univ., sect. C, (36): p. 235-260, pis. 9-12.Webb, G. E., 1990. Lower Carboniferous coral fauna of theRockhampten Group, east-central Queensland. In ,Devonian and Carboniferous coral studies (ed. P.A. Jell ), p. 1-167. Association of AustralianPalaeontologists, Brisbane.Yabe, H., 1958. Thick limestones of the Upper Carbon-iferous-Permian age in Japan. An interpretation oftheir mode of deposition. Proc. Japan Acad., 34:p.4.A New Species of Lithostrotion (SipJwnodendron) (Rugosa)PLATE 1Nobuo Yamagiwa, Shigeyuki Suzuki and Yuji OkimuraExplanation of Plate 1Figs/ 1-7. Lithostrotion (Siphonodendron) hinensis Yarnagiwa, Suzuki and Okimuran. sp.1. Transverse section-------------------------X4 (ESO-FO 100 1a)a. Section showing tabularial increase ofcoraliites2. Transverse section-------------------------X16 (ESO-FO I00 1a)3. Transverse section-------------------------X16 (ESO-FO 1001 a)4. Transverse section-------------------------X4 (ESO-FO 100 1b)5. Longitudinal section-----------------------X4 (ESQ-FO 100 Ic)a. Typical sectionb. Section showing tabularial increase ofcorallites6. Typical longitudinal section--------------XI6 (ESO-FOI00lc)7. Typical longitudinal section--------------X4 (ESO-FOlOOld)A New S~cies or Urhostrorioll (SipllOllodel/droll) (Rugosa)Yamagiwa, Suzuki and Okimura Plate I

A New Species of Lithostrotion (Siphonodendron)(Rugosa) from the Hina Limestone, Okayama Prefecture, Southwest Japan

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