Studies on Morphological forms of Staphylotrichum Coccosporum

Staphylotrichum coccosporum Meyer & Nicot was described as an inhabitant of tropical soils (3). The authors indicated the variability of the species with reference to minor morphological details, color of cultures, and sporulation on artificial media. Although this is the only report in available literature of this fungus, it is commonly found in soil used in Purdue University greenhouses, usually as much as 5% of the microflora. The species is associated with cellulose decomposition and, with cellulose-amended soil, can be isolated in much larger numbers. The morphology and variability of 86 isolates grown on potatodextrose-agar medium were compared. Several morphological types were distinguished in wild-type cultures. Three mutant types arose in culture media. WILD TYPES. Variation occurs between isolates in: (1) mode of formation of conidial stalks, (2) length of conidial stalks, (3) mode and degree of branching of conidiophores, (4) spore size, (5) color. Conidial stalks may arise on a hard, spherical to ellipsoidal base, averaging 45 X 36 u, distinct from the underlying mycelium (FIG. 1, d, e). Several such units may originate from the same point. In other isolates, conidial stalks are formed in groups (FIG. 1, f, g) or singly. In intermediate types, the underlying mycelium forms more or less compact, sometimes pseudoparenchymatous, masses on which conidial stalks develop. A pore is centrally located at each septum of a conidial stalk (FIG. 1, g). The average length of conidial stalks ranges from 805 to 1182 p, so that short, intermediate, and long-stalked isolates occur (FIG. 1, a, b, c). The fertile part of the conidial stalk is 16 to 21% of the