A New Species of Neurospora from Wisconsin Lowland Soil

Abstract

In the course of an investigation of the soil microfungi in certain Wisconsin floodplain forest communities, an interesting pyrenomycetous fungus was encountered which appears not to have been previously described. A single isolate of the organism, WSF 5000, was obtained following steaming (Warcup, 1951) of a sample of soil taken from a cottonwood grove at Spring Green, Wisconsin. The soil sample was collected on November 18, 1961 and processed the following day. The fungus in question developed perithecia containing cylindrical asci with eight, dark, ovoid, single-celled sculptured spores. The form and structure of the fructifications, together with the character of the ascospores, suggested that the fungus isolated was a species of Neurospora. Subsequent study showed, however, that no conidia are produced by this fungus on any of several media employed. It was also revealed that WSF 5000 differs from Neurospora species previously described in having typically oval ascospores with a single germ pore at each end, and that it is homothallic whereas all previously-known Neurospora species with 8-spored asci are heterothallic. Shear and Dodge (1927), in erecting the genus Neurospora, specified in their diagnosis a Monilia imperfect stage as a feature of the taxon. Since no such stage could be found in the pyrenomycete isolated from Spring Green soil, it was apparent that either a new genus would have to be proposed to receive the entity represented by WSF 5000 or the description for Neurospora would need to be modified so as to accomodate it. Because WSF 5000 is so similar to the described species of Neurospora in a large number of significant features, the writers believe that the latter procedure is more appropriate and accordingly suggest that the generic description for Neurospora as set forth by Shear and Dodge be emended to include forms lacking a Monilia imperfect stage. The following new species is assigned to a position in the genus thus remodeled: