Introduction to Fungi, Third Edition

ASCOBOLUS (ASCOBOLACEAE)
419
Aleuria is similar in appearance to Peziza (see
below) but is distinguished from it in having
non-amyloid asci. The best-known species is A.
aurantia, the so-called orange-peel fungus which
forms strikingly orange-coloured cup-shaped
apothecia from about 1 10 cm in diameter in
woodland and grassland soil during autumn
(Plate 6b). Isotopic analyses of ascocarps using
15 N and 13 C isotopes indicate that the fungus
may be mycorrhizal (Hobbie et al., 2001). The
orange colour of the hymenium is due to
carotenoid-enriched granules in the club-shaped
tips of the paraphyses (Fig. 14.3). The main
carotenoids are b-carotene, g-carotene and aleuriaxanthin
(Gill & Steglich, 1987).
The ascospores contain two lipid globules and
the ascospore wall is ornamented by a honeycomb-like
series of raised ridges which represent
secondary wall material. It is derived from
granules in the perisporic sac which condense
into larger spherical dense bodies. These accumulate
and become attached to the epispore
(Merkus, 1976; Wu & Kimbrough, 1993).
14.4 Peziza (Pezizaceae)
Peziza is a large genus containing around
100 species. Analyses based on a combination
of morphological and molecular evidence indicate
that this genus is polyphyletic, i.e. it
contains a number of unrelated taxa which
have been grouped together artificially. Peziza
in its traditional sense can be differentiated
into at least eight clades (Hansen et al., 2005).
Hohmeyer (1986) has provided a key to European
species. For descriptions and illustrations see
Dennis (1981), Breitenbach and Kränzlin (1984)
and Dissing et al. (2000). The apothecia are cupshaped,
often large (2 5 cm or more), usually
pale brown and fleshy (Plate 6c). They are
commonly encountered in a very wide range
of habitats including soil, manure heaps, dung,
rotting wood or straw, burnt ground and sand
dunes. About six species have hypogeous ascocarps
(Trappe, 1979). The ascus wall is, in general,
amyloid. In P. succosa the blue-staining by I 2 /KI
is confined to the ascus apex (Samuelson, 1978a).
Fig14.3 Aleuria aurantia. Asci, ascospores and paraphyses.
The tips of the paraphyses are filled with granules containing
orange-coloured carotenoids.
The conidial states of Peziza spp., where known,
have been classified in the anamorph genus
Oedocephalum (Fig. 14.4).
A genus with more strikingly coloured apothecia
is Sarcoscypha (Plate 6e). Although similar
in appearance to Peziza, these two genera are not
closely related (Landvik et al., 1997).
14.5 Ascobolus (Ascobolaceae)
There are about 80 species of Ascobolus
(van Brummelen, 1967). Most of them are