A New Microsporangial Protostelid,Microglomus paxillus gen. and sp. nov.*

SYNOPSIS. Microglomus paxillus is described as a new genus and species of the subclass Protosteliida (Class Eumyceto-zoa). It has been isolated only once from casuarina bark collected in Oahu, Hawaii. The new organism is characterized by a uninucleate ameboid trophic stage that feeds on bacteria and by sporocarps with spike-like stalks terminated by microspo-rangia containing tetrads of ameboid protoplasts or thin-walled spores. No flagellate cells are produced. The tetrads are typically formed by successive bipartition following conjugate nuclear divisions in the sporogen. The cells of the tetrad are at first binucleate but soon become uninucleate as a result of nuclear degeneration. Variations in the process of sporogenesis are described.