Some New Species of Hypoxylon

Abstract

The descriptions of the following new species of Hypoxylon are based on specimens sent the writer by Dr. Roland Thaxter and Prof. A. S. Muller, and others of his own collecting. The forms which are given varietal names do not differ from the established species in sufficient characters to warrant specific rank. In most cases they are distinct only in ascospore dimen? sions. This latter character varies considerably with material of different ages, but there is a fairly definite maximum limit. For example, Hypoxylon serpens Pers. ex Fries has ascospores which vary in length from 10 to 15 /x. This species was described from Europe and all material examined there falls within these limits. In America, however, the European form is very com? mon, but occasionally one finds what is apparently the same thing except for the much larger ascospores; that is, between 15 and 20 ix, in length. These variants may be mutants or hybrids, but in view of the present lack of knowledge of inheritance in the fungi, it seems best to give them varietal rank.