Structure and Development of Lasiobolus monascus, a New Species of Pezizales, Ascomycetes

SUMMARYMorphological and cytological development of a new uniascal species of Lasiobolus is described. Although some of the excipular hairs are atypical of the genus, microscopic and microchemical features of the large operculate ascus, the ascospores, and excipulum are characteristic of known species of Lasiobolus. In culture adjacent mycelial cells function as ascogonia and antheridia. After fertilization the single ascogonial cell enlarges and becomes the ascus. The ascocarp is cleistohymenial, opening shortly before spore liberation. The relationship and evolutionary significance of this species are discussed.