Experimental Studies With A New Species of Stigmatomyces (Laboulbeniales)

SUMMARY

Stigmatomyces ceratophorus on Fannia canicularis appears to be a most likely combination for experimental studies in the Laboulbeniales. The host is relatively easy to maintain in the laboratory and the fungus is large and easily manipulated. Infection may occur on almost any external portion of the host, but, in primary infections, is usually found in a ventral position on the males and dorsally on the females. This primary positioning is related to transmission at mating. Secondary spread from the back to the legs is especially common in females. These observations may help reconcile the published differences between Thaxter (1896) and Peyritsch (1875) on position specificity in Stigmatomyces. Quantitative evidence suggests that the fungi do not shorten the life span of the host. Holes penetrating the host are obvious and it is clear that the thallus obtains nutrients from the underlying tissues of the fly. Spores placed on fly-wings on nutrient medium responded to changes in that medium. The fly-wings could not be replaced by chitin or cellulose membranes. Relatively large, spermatia-producing plants may be grown to the 20-cell stage in pure culture.