A New Species of the Leptomitidae(Demospongea) from the Lower Cambrian Chengjiang Biota in Yunnan Province

The new studied fossil sponges Styloleptomitus erjiensis gen sp.nov.are of total different structure and characteristics from the past and usual ones.Through comparing new species to the three advantages of Leptomitus,Leptomitella and Paraleptomitella in the fossil sponges,the article is based on comprehensively analysis on the external characteristics,the spicule type and its spicules combination type,and through comparing with other usual and common sponges bottom structure of Chengjiang Biota.The result show that a new species of Leptomitidae,Styloleptomitus erjiensis gen sp.nov.,which is characterized by many curved styles at the bottom of the body which gradually transited into long axes toward the body summit.The styles at the bottom of the sponge serve as a ballast to rest on the substrates,probably it represents a transitional settlement type between that of Crumillospongia and other species of Leptomitidae.