Middle Permian rugose corals from Laibin, Guangxi, South China

Abstract

The Middle Permian Chihsia and Maokou formations in Laibin, central Guangxi, South China contain 19 rugose coral species; of these taxa,Lophocarinophyllum sandoi, Asserculinia solida, andInnixiphyllum wuaeare new.Innixiphyllumrepresents a new genus characterized by contratingent minor septa. Ten species are reviewed and described in detail, and the diagnoses of three of these species,Allotropiophyllum heteroseptatum(Grabau, 1928),Lophocarinophyllum taihuense(Yan and Chen, 1982), andIpciphyllum regulare(Wu, 1963), are newly emended. The morphological variation and ontogenetic changes of the solitary, nondissepimented species are particularly emphasized. Six additional taxa are described and illustrated but are left in open nomenclature.The corals from Laibin are typically Tethyan. Four biostratigraphic assemblages are recognized: an assemblage of massive corals in the upper Chihsia Formation represented byPolythecalis longliensis; an assemblage of small solitary and nondissepimented corals in the lower Maokou Formation, dominated by species ofAllotropiophyllum, InnixiphyllumandLophocarinophyllum; an assemblage of mixed massive colonial and small solitary corals in the middle Maokou Formation, characterized byIpciphyllum regulare; and an assemblage of solitary nondissepimented corals in the uppermost Maokou Formation, characterized byUfimia elongata. These assemblages correspond well to those from other areas of South China. In Laibin, only two rugose taxa,Amplexocariniasp. andParacaninia minor, occur in the basal part of the Wuchiaping Formation of Lopingian age.