Aenigmatomyces, an Enigmatic New Genus of Fungi from Algonquin Park, Canada

Abstract

We led mycological field courses in Algonquin Park, Ontario, during September of 1991 and 1992. On each occasion, though in different parts of the park, while making collections of other microfungi on dead leaves, we inadvertently made a small collection of a delicate, colorless, undescribed organism. While this obviously belonged to the fungal Union (Barr, 1992), it could not be readily placed in any existing fungal species, genus, order, class or even phylum. This enigmatic organism produced branched, septate, somatic hyphae, closely applied to, and possibly parasitizing, the hyphae or thick-walled spores of another fungus (one of the substrate fungi was tentatively identified as a Pythium sp.). Specialized spore-producing hyphae arose from the somatic hyphae. The distal two-thirds of each sporiferous hypha was closely septate. From each ofthe up to 35 short cells thus delimited arose single, lateral, finely tapering, needle-like extensions. At the tip of each extension, a single, apically pointed, ampulliform spore was produced. Significantly, during sporogenesis the entire con? tents of the sporiferous cell and of its lateral ex? tension migrated into the spore, which then seceded fairly readily, though sometimes taking with it a narrow apical fragment of the sporif? erous extension. This total evacuation of a spo? riferous cell is rare among members of the phy? lum Dikaryomycota (Ascomycotina plus Basidiomycotina), but is often seen in the protoctistan fungi (e.g., phyla Oomycota and Chytridiomycota). Although we have collected the fungus only twice and have not been able to establish it in axenic culture (spores plated out on malt extract agar failed to germinate), we consider this or? ganism to be so unusual as to be worth bringing to the attention of other mycologists. We describe a new taxon in the hope that others will rediscover it and perhaps be able to place it in an appropriate taxonomic niche.