Four keys are presented. Keys [1] and [2] (MJR) are to the coprophilous ascomycetes, a very diverse group which, although not covering all the possible types of reproductive structure found in the class, contains many of the important types. The information for the identification of these fungi is dispersed throughout the literature, and many new species are still being discovered and described. Some appear to be world-wide in their distribution, others more restricted, with a prevalence of reports from either arctic, temperate or tropical regions. These keys are not exhaustive, since there are far too many species to make it practical to include them all. They do, however, include most genera, and the commoner or well known species of temperate regions. Specific (and even generic) limits in some cases (e.g. Coprotus / Ascophanus / Ryparobius / Thelebolus) are still the subject of debate and the choice of names to use in the key for a few taxa has been a compromise. [Key 2] includes the original 'plectomycete' key (RW), which contains fungi which may not be strictly coprophilous in the normal sense, but fungi which occur on hair, horn, bone and cadavers, and may thus be found on carnivore dung or pellets of owls and other birds of prey.
[Key 3] (RW, p. 52) is to the basidiomycetes of dung and associated debris. The part of the key dealing with the agarics attempts to be as complete as possible. Since the toadstools have always been thought of as the best known of the coprophilous fungi, attention to their taxonomy has often been careless. In this key the opportunity has been taken to adopt a rather narrow species concept, and to provide in certain places indications of where distinct taxa, even autonomous species, may be found after further laboratory work. Many of these types have been cultured and appear to differ vegetatively in ways which support observations of gross morphology. Coprophilous agarics are popular material for genetic studies and additional information on veil structure, spore number etc. of individual species is given, even when these are not 'key characters'.
[Key 4] (MJR, p. 63) is to the Zygomycota (phycomycetes) which are characteristic of dung and amongst the first to appear when freshly dropped dung is incubated. They soon disappear, however, but their fruiting can be prolonged by plating small portions of dung on a nutrient medium (e.g. potato carrot or potato dextrose agar) to which has been added a small amount of antibiotic to reduce bacterial growth. This method is especially suitable for the parasitic and predacious fungi. A cultural approach is essential for the identification of many of these fungi and the above media, and oatmeal agar, are suitable for culture as well as isolation. For this reason the study of this group of fungi is less easy than that of the ascomycetes and basidiomycetes but, because the asexual stages are characteristic, we have attempted to key out the commoner genera which might be found, with notes on common species. The asexual spores are sporangiospores formed in sporangia; some sporangia produce a single spore within a closely fitting sporangium, and have in the past been erroneously described as conidia. A great range of sporangial structure occurs within the orders concerned. The classical structure is the massive (up to 250µm diam.) multispored sporangium with an internal columella which remains after the spores have been dispersed (e.g. Mucor); those of Mortierella are similar, but smaller and without a columella. Other sporangia are much reduced and may be only 10-20µm diam., and contain only a small number of spores (Thamnidium) or one spore (Chaetocladium); these small globose structures are termed sporangioles. Spores may also form in chains; the chains are in terminal groups and are formed by the differentiation of the contents of cylindrical sporangia which are considered to be part-sporangia (merosporangia). When the sporangial wall has disappeared the spore chains may remain discrete and intact, or they may collapse into a wet droplet of spores (Syncephalastrum, some Piptocephalis). Members of the Kickxellaceae (e.g. Coemansia, Kickxella) have single spored merosporangia produced in serried ranks on boat-shaped or swollen structures (sporoclades). The sexual spores (zygospores) are rarely seen without culturing; oatmeal agar is one which favours their production. The key includes one member of the Entomophthorales, which also produces single-spored sporangia. Other members of this order may be found parasitising the various animals which live in dung; many other predacious fungi may also be seen, e.g. parasites of amoebae (Acaulopage). The key is of necessity far from complete, and omits members of the Dimargaritales, which have been found frequently on dung of small mammals in America.
Mitosporic fungi ('Fungi Imperfecti') and myxomycetes have been excluded, since they would expand the range of these keys beyond what was initially intended, although numerous species of both groups occur on dung when incubated in a damp chamber. For mitosporic fungi see Seifert, Kendrick & Murase (1983) and Ellis & Ellis (1988); for myxomycetes see Eliasson & Lundqvist (1979). As practical keys, rather than a taxonomic treatment, taxonomic authorities have not been cited. For ascomycetes, Cannon, Hawksworth & Sherwood-Pike (1985) have been followed, unless there is a more recent treatment of a group. For the basidiomycetes the 'New Checklist of British Agarics and Boleti' (Dennis, Orton & Hora, 1960, Supplement to the Transactions of the British Mycological Society 43) has been followed, and The British Fungus Flora (Orton & Watling, 1979 and Watling, 1982).
ASCOMYCETE REFERENCES
Ahmed, S. I. & Cain, R. F. (1972). Revision of the genera Sporormia and Sporormiella. Canadian Journal of Botany 50, 419-477. (Keys and descriptions of 66 spp.).
Apinis, A. E. (1964). Revision of the British Gymnoascaceae. Mycological Paper 96.
Arx, J. A. von (1971). On Arachniotus and related genera of the Gymnoascaceae. Persoonia 6, 371-380.
Arx, J. A. von (1975). Revision of Microascus with the description of a new species. Persoonia 8, 191-197.
Arx, J. A. von (1975). On Thielavia and some similar genera of Ascomycetes. Studies in Mycology 8.