The Late Devonian brachiopodCyrtiopsis davidsoniGrabau, 1923, and related forms from central Hunan of South China

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New specimens representing species ofCyrtiopsisGrabau, 1923, described by Grabau (1931a) were recovered in samples from the Late Devonian deposits of the Changlongjie Member of the Xikuangshan Formation in central Hunan Province of South China. Associated Famennian age conodonts and morphotypes of the rhynchonellid brachiopodYunnanellinalineage fix the ranges of species ofCyrtiopsisand related taxa in the Xikuangshan Formation within the interval of the MiddletriangularisZone through the LowercrepidaZone (early Famennian) in central Hunan Province.Detailed study and comparison of external and internal shell structures of the type species ofCyrtiopsisGrabau, 1923, and related species described in Grabau (1931a) shows thatCyrtiopsisfrom South China includes the type species,C. davidsoni(embodied by the holotype), andC graciosa.Both of these species are shown to lack a delthyrial plate. Grabau's paratypes ofC. davidsoniare considered to belong inCyrtiopsis intermediaGrabau, 1931. The speciesC. kayseriGrabau, 1931, andC. shensiensisGrabau, 1931, are also deemed synonyms ofC. davidsoniGrabau, 1923 (as restricted above).“Cyrtiopsis” intermediadiffers from other species ofCyrtiopsisby development of a short delthyrial plate and its systematic position remains uncertain.The genusPseudocyrtiopsisis proposed withCyrtiopsis spiriferoidesGrabau, 1931, as the type.Pseudocyrtiopsisnew genus is distinguished fromCyrtiopsisGrabau, 1923, by its alate hinge and development of a delthyrial plate. Comparisons of species ofCyrtiopsisfrom South China with cyrtospiriferid brachiopods identified asCyrtiopsisby Crickmay (1952) demonstrate that none of the early Famennian species from western Canada can be assigned to the genus as revised here, althoughC. mimetesCrickmay, 1952, is closely related to“C.” intermediaGrabau, 1931.