. This phylum includes morels , a few mushrooms and truffles , single-celled yeasts (e.g., of the genera Saccharomyces , Kluyveromyces , Pichia , and Candida ), and many filamentous fungi living as saprotrophs, parasites, and mutualistic symbionts. Prominent and important genera of filamentous ascomycetes include Aspergillus , Penicillium , Fusarium