论志留纪的小莱采贝类——具壳线、无疹无窗贝族(腕足动物)

THE RETZIELLIDAE(SILURIAN RIBBED IMPUNCTATE ATHYRIDIDINE BRACHIOPODS)

对志留纪ＧａｎｎａｎｉａＦｕ１９８２，ＰｒｏｔａｔｈｙｒｉｓｉｎａＺｈｕ１９７４和ＳｔｅｇｏｓｐｉｒａＦｕ１９８２等３属模式种地模标本的再研究，表明它们的基本特征，尤其是主基和腕螺（包括腕锁）构造，均与ＲｅｔｚｉｅｌｌａＮｉｋｉｆｏｒｏｖａ１９３７属一致，后者是首异名（ｓｅｎｉｏｒｓｙｎｏｎｙｍ），应予保留，前３属是次异名（ｊｕｎｉｏｒｓｙｎｏｎｙｍｓ），应该废弃。曾被国外学者视作识别泥盆纪Ａｔｈｙｒｉｓｉｎａ属（模式种为ＡｔｈｙｒｉｓｉｎａｓｑｕａｍｏｓａＨａｙａｓａｋａ）的标准的ＡｔｈｙｒｉｓｉｎａｍｉｎｏｒＨａｙａｓａｋａ１９２０，系Ｐｒｏｔａｔｈｙｒｉｓｉｎａ的模式种Ｐ．ｋｕｔｓｉｎｇｅｎｓｉｓＺｈｕ１９７４的同义名，现改归Ｒｅｔｚｉｅｌｌａ属。以上４属曾被有些学者视为ＭｏｌｏｎｇｉａＭｉｔｃｈｅｌｌ１９２１的同义名。经笔者重新研究地模标本及其系统切面后发现，Ｍｏｌｏｎｇｉａ的模式种Ｍ．ｅｌｅｇａｎｓＭｉｔｃｈｅｌｌ１９２１与ＲｅｔｚｉｅｌｌａｗｅｂｅｒｉＮｉｋｉｆｏｒｏｖａ１９３７尽管腕骨构造类型相同，但它们的主基特征有着重要区别，后者发育隔板槽和中隔板，前者缺失这两种构造，仅具低短的肌隔。因此，

Five brachiopod genera- Gissarina Menakova et Nikiforova 1986, Metathyrisina Rong et Yang 1981, Molongia Mitchell 1921, Qinlingia Rong, Zhang et Chen 1987, and Retziella Nikiforova 1937-formerly assigned to the superfamily Retziacea Waagen 1883 or the superfamily Athyrisinacea Grabau 1931, are now combined in the Silurian to earliest Devonian family Retziellidae Rzhonsnitskaya 1974, within the athyrididine superfamily Meristelloidea. Retziella is the most common genus widely distributed in many areas and Molongia is a local offshoot of Retziella. Other three genera- Gannania Fu 1982,Protathyrisina Zhu 1974,and Stegospira Fu 1982-formerly regarded as synonyms of Molongia, are placed in synonymy with Retziella.Assignment of Argorhynx Havlicek 1992 and U fonicoelia Haviieek 1992 is uncertain since there are no available data on dorsal interiors.The genera Athyrisinoides Jiang 1978,Dabashanospira Fu 1982 1 Ornothyrella Havlicek 1971 and Plectothyrella Temple 1965 are excluded from the Retziellidae.The family and its two genera(Retziella and Molongia)are herein revised and a diagnosis is provided based on examination of holotypes or topotypes of the type species of most genera discussed here. Metathyrisinidae Wang,Rong et Yang 1981 is considered a subjective synonym of Retziellidae. The relationships between many species of Retziella are clarified on the basis of newly examined internal structures. Most of these genera form an important component of the Retziella Fauna, distinctive in the later Silurian to earliest Devonian of Central Asia,China,Southeast and possibly Southwest Asia,and Australia.