The Genera of Hyphomycetes project, and provides a comprehensive overview of all fungal groups from a phylogenetic perspective (Spatafora 2005, Blackwell et al. 2007, Hibbett et al. 2007). The latter project provides the basis for most of the larger scale phylogenetic trees presented in this introduction, which show the relationships of selected hyphomycete genera in the series starting with Fig. 6.
B. What are hyphomycetes? Hyphomycetes make up the majority of what are commonly called moulds1, and some are regarded as the weeds of the fungal kingdom. In addition to growing on many natural substrates such as plant tissues (Fig. 5), wood and bark (Fig. 7), dung (Fig. 12), insects and other arthropods (Figs 14, 22), and other fungi (Fig. 16, 38B) including lichens (Fig. 18), and in a diversity of ecological habitats, moulds are involved in food spoilage, contaminate many manufactured materials such as wood, paper and textiles, and are frequent visitors to the human indoor environment. Some hyphomycetes are asexually reproducing parts of the life cycle of sexually competent ascomycetous and basidiomycetous fungi. The asexually, or mitotically, reproducing structures are called anamorphs; the sexually reproducing, or meiotic, counterparts of the same life cycle are called teleomorphs. Together, these forms of sporulation make up a whole fungus, or holomorph (Fig. 4, Hennebert & Weresub 1977, Weresub & Hennebert 1979). In some cases, anamorph and teleomorph develop side-by-side, but more commonly they mature at different times, or on different substrates. Historically, the establishment of anamorph–teleomorph connections was difficult. Although thousands of connections are known, the majority of hyphomycetes remain orphaned. It seems almost certain that many anamorphs have permanently lost the potential to mate or to develop a teleomorph, and must be regarded as anamorphic holomorphs. Mycologists must classify such anamorphic holomorphs pragmatically, using whatever characters are available. Mycologists generally recognize three major groups of anamorphic fungi. None of these three groups is a homogeneous, phylogenetically based taxon: they are polyWe consider ‘mould’ the correct spelling for a fungus, reflecting its etymological origin from the English ‘moul’, different from ‘mold’, i.e. a container for making a shape.
1
Fig. 4. The first anamorph-teleomorph connection. A. Discovered by Anton de Bary (1831–1888) (public domain). B. Aspergillus anamorph (green) and Eurotium teleomorph (yellow) in one agar colony. C. Conidiophores of Aspergillus anamorph of Eurotium. D. Eurotium teleomorph, optical section of ascoma on left, ascospores in asci on right. The teleomorph and anamorph together comprise the holomorph.
5
What are hyphomycetes?
than Myxomycetes or Myxomycota, because the endings ‘-mycetes’ or ‘-mycota’ imply a fungal nature, and we refer them to Kingdom Protozoa. The ‘cellular slime moulds’ (Phylum Dictyostelida), the ‘net slime moulds’ (Phylum Labyrinthulida) and the ‘endoparasitic slime moulds’ (Phylum Plasmodiophorida) are now also classified in the Kingdom Protozoa. Even with slime moulds excluded, the organisms we generally call ‘fungi’ are not monophyletic. Organisms that look distinctly fungal under the light microscope, because in many cases their colonies are built up of branching hyphae, are now placed in two different Kingdoms. The ‘water moulds’ and ‘downy mildews’ of Phylum Oomycota (and the tiny Phylum Hyphochytriomycota) are now understood to belong in Kingdom Chromista (sometimes called Stramenipila), the Kingdom that also contains the diatoms and the brown algae. These Chromistan pseudofungi differ from true fungi in many important ways: their heterokont flagellation, a wall chemistry that includes cellulose, somatic ploidy, mitochondrial cristae, lysine biosynthesis, etc. After the slime moulds and the pseudofungi are excluded, the true Fungi comprising the Kingdom Eumycota remain, as defined in the first paragraph of this section. The hyphomycetes are all members of this Kingdom, but they are found in two different Phyla, the Ascomycota and the Basidiomycota. We currently recognize six Phyla (also known as Divisions) in Kingdom Eumycota or the Fungi (see Kendrick 2010): Phylum Chytridiomycota Phylum Zygomycota Phylum Glomeromycota Phylum Ascomycota Phylum Basidiomycota Phylum Microsporidia (recently recognized as reduced or secondarily simplified fungi, but still under zoological nomenclatural rules). The phyla Ascomycota and Basidiomycota together comprise the subkingdom Dikarya. It is unnecessary for us to describe and differentiate the major fungal groups here. Motivated readers can pursue this matter in Cavalier-Smith (2001), Kirk et al. (2008), and Kendrick (2010), or other modern general mycology texts. The Nov.–Dec. 2006 issue of Mycologia includes the results of the ‘Assembling the Fungal Tree of Life’