Revision of the Seuratiaceae. I. Morphology of Seuratia

Abstract

The type genus of the family Seuratiaceae is described as consisting of four highly variable species. The origin and location of the conidiogenous areas (sporodochia), pycnidia, and pseudothecia are demonstrated to be related to the size and shape of the colonies, which are in turn dependent upon ecological factors of substratum and duration of wet season. The microstructure of the intercellular matrix varies from amyloid through pseudoamyloid to inamyloid. Each of these characteristics completely intergrades between the extremes. The pattern is considered to reflect nutritional differences rather than climatic factors. Asexual reproduction is by multicellular, holoblastic thallospores originating from superficial layers of the colonies. The variation of the thallospores (conidia) arises from indeterminate but ecologically limited growth. Asci arise from superficial croziers which proliferate indefinitely before aborting. The zone of ascogenous tissue is therefore a pseudothecium. Pseudoparaphyses are lacking but an indefinite epithecium is sometimes found. Interthecial tissue arises from budding croziers or by their abortion and from persistent sterile tissue. With the production of mature asci, colonies cease to grow and soon drop from the leaves.