A new middle Permian waagenophyllid rugose coral species, Ipciphyllum dilatum sp. nov. from the Shan Plateau, Myanmar

A new rugose coral, Ipciphyllum dilatum sp. nov. is described and illustrated from the Thitsipin Limestone of the Plateau Limestone Group of middle Permian (Roadian-Wordian) substages of the Shan Plateau, Myanmar. This new taxon is distinct from all other previously described species by having all septa in the tabularium being dilated, smaller corallite diameter, and lack of the medial plate in the axial column. It is palaeogeographically significant that it co-occurs with other middle Permian rugose coral species, Yatsengia hangchowensis, Iranophyllum sp. cf. caracinophylloides, Ipciphyllum subelegans, Pavastehphyllum sp., Pavastehphyllum (Thomasiphyllum) sp. in the Linwe area of the Shan Plateau region. This fossil assemblage is correlated with that of China, Thailand, Iran, and Malaysia. The similarities of middle Permian rugose corals between Myanmar and Malaysia clearly indicate that both were at a close paleogeographic position likely in the Cathaysian paleogeographic provinciality during the middle Permian. The new species demonstrates variability within five parameters: number of sides of corallite wall, nature of septa, number of septa, development of dissepiments, and variation of axial structure. From this work, it should be noted that, intraspecific variability is one of the basic criteria for identification of the rugose coral species.