A remarkable new halichondrid demosponge, Ptilospongia hemisphaeroidalis, from the latest Ordovician Beigong Biota, South China

A new halichondrid demosponge bubarid Ptilospongia hemisphaeroidalis gen. et sp. nov. is de scribed from the latest Ordovician Beigong Biota in Jingxian County, Anhui Province, South China. The new taxon is well-preserved with a two-layer choanosomal skeleton structure (basal layer and erect monactines layer) and three different types of megascleres (styles, strongyles, strongyloxeas), providing an excellent insight into a bubarid affinity and indicating a previously unknown group. It probably represents the earliest known fossil record of bubarids, providing a more reliable calibration point currently available for taxonomic and molecular phylogenetic studies.