西秦岭迭部地区早志留世四射珊瑚动物群

EARLY SILURIAN RUGOSE CORAL FAUNA OF TEWO AREA, WEST QINLING

西秦岭迭部地区下志留统拉垅组四射珊瑚已报道８ 属１０ 种，作者近年对该珊瑚动物群详加研究，经鉴定计有９ 科，１３ 属，１８ 种，描述其中１１ 属１２ 种（ 包括５ 新种），即Ｂｒａｃｈｙｅｌａｓｍａ ｓｐ ．， Ｐａｒａｍｐｌｅｘｏｉｄｅｓ ｓｐ．， Ｋｏｄｏｎｏｐｈｙｌｌｕｍ ｃｆ． ｌｅｉｊｉａｔｕｎｅｎｓｉｓ Ｇｅ ｅｔ Ｙｕ， Ｅｏｓｔａｕｒｉａ ｍｉｎｏｒ（Ｃｈｅｎ） ， Ａｍｐｌｅｘｏｉｄｅｓｃｈａｏｉ（Ｇｒａｂａｕ） ， Ｔｒｙｐｌａｓｍａ ｃｆ． ｍｕｌｔｉｔａｂｕｌａｔａ Ｎｉｋｏｌａｉｅｖａ， Ｔ．ｓｐ ．， Ａｐｈｙｌｌｕｍ ｔｅｗｏｅｎｓｅｓｐ ．ｎｏｖ．， Ｃｙｓｔｏｃａｎｔｒｉｌｌｉａｓｉｌｕｒｉｃａ ｓｐ ．ｎｏｖ ．， Ｃｙｓｔｉｐｈｙｌｌｕｍ ｙｉｗａｅｎｓｅｓｐ ．ｎｏｖ ．， Ｇｙａｌｏｐｈｙｌｌｏｉｄｅｓｓｉｍｐｌｅｘ ｓｐ．ｎｏｖ．，Ｐｓｅｕｄａｍｐｌｅｘｕｓｉｎｔｅｒｍｅｄｉｕｓ ｓｐ ．ｎｏｖ．。该动物群可与扬子区中Ｌｌａｎｄｏｖｅｒｙ 期雷家屯组珊瑚群对比，同属于扬子生物地理区。

The Early Silurian rugose coral fauna of Tewo area, West Qinling was first reported in 1990. Recently, the fauna has been researched in detail, including 9 families, 13 genera and 18 species. In this paper, 11 genera and 12 species (of which 5 are new) are described. They are: Brachyelasma sp., Paramplexoides sp., Kodonophyllum cf. leijiatunensis Ge et Yu, Eostauria minor (Chen), Amplexoides chaoi (Grabau), Tryplasma cf. multitabulata Nikolaieva, T. sp., Aphyllum tewoense sp.nov., Cystocantrillia silurica sp.nov., Cystiphyllum yiwaense sp.nov., Gyalophylloides simplex sp.nov., and Pseudamplexus intermedius sp.nov. All specimens are collected from the upper member of Lalong Formation (M.Llandovery) in Tewo area, West Qinling. This fauna may be correlated with the Leijiatun Formation (M. Llandovory) of northeastern Guizhou, indicating the Early Silurian rogosan fauna from West Qinling to be close to those of Yangtze region in biogeographical affinity, and it may belong to the Yangtze Province. Family Tryplasmatidae Etheridge, 1907 Genus Aphyllum Soshkina, 1937 Aphyllum tewoense sp. nov. (Pl.Ⅰ, fig.7) Description Corallum phaceloid, composed of large cylindrical corallites,with connecting processes. The adjacent corallites always contacted with one or two sides, acanthine septa very developed in the corallite, about 50 in number. Epitheca thick, 0.5-1 mm in width. Tabulae complete, nearly flat, or concave in the middle portion, 3-5 in a space of 5 mm. Comparison This new species is similar to Aphyllum sociale Soshkina, but it differs from the latter in having a larger corallite and longer acanthine septa. The new species is also similar to Aphyllum multiseptata Huang, the main difference from the latter lies in that it has somewhat uniform corallites in size, more numerous acanthine septa and tabulae often concave in the middle part. Occurrence and horizon Lower Silurian, Upper member of Lalong Formation, Gagu, in Yiwa countryside, Tewo County, Gansu Province.