Introduction to Fungi, Third Edition

572 HOMOBASIDIOMYCETES
(Talbot, 1977). Severe infections of pine plantations
are thought to be due to a synergism
between the fungus and its insect vector,
and are particularly common in the Southern
Hemisphere.
19.7.4 Auriscalpium
The fruit bodies of Auriscalpium have a toothed
hymenium, but molecular sequence studies have
shown that the genus is related to the gillbearing
Lentinellus and the clavarioid fungus
Clavicorona (Pine et al., 1999), both included in
the russuloid clade (Fig. 19.2). Auriscalpium
vulgare, the earpick fungus, is distributed in the
Northern Hemisphere. It grows on buried pine
cones, forming stalked, one-sided, brown, hairy
fruit bodies during autumn and winter
(Fig. 19.26e). The hyphal construction is dimitic
with skeletals. The hymenium is formed on
vertical, finger-like downgrowths from the
underside of the pileus. Interspersed amongst
the basidia are irregularly enlarged, thin-walled
hyphal tips with highly refractile contents,
gloeocystidia (Fig. 19.29). Basidiocarps show
rapid gravitropic readjustment to the vertical
position if displaced laterally. The mating
system of Auriscalpium is bifactorial, i.e.
tetrapolar (Petersen & Wu, 1992; Petersen &
Cifuentes, 1994).
19.8 Thelephoroid clade
This includes the order Thelephorales, a small
group of predominantly ectomycorrhizal fungi
with variable basidiocarps. The most important
genus is Thelephora (c. 50 spp.). The earth fan
T. terrestris (Plate 10e) produces clusters of fanshaped
basidiocarps which are chocolate-brown
in colour with a paler margin. They are
often formed around the stem of young trees,
seemingly ‘choking’ them. Basidiocarps of
T. terrestris superficially resemble those
of Stereum but are monomitic, composed of
clamped generative hyphae only. The basidiospores
are brown and warty. Thelephora terrestris
fruits in association with coniferous trees
growing on light sandy soils and heaths. It is
Fig19.29 Auriscalpium vulgare.
(a) Spine from the underside of the
basidiocarp cap. (b) Portion of the
hymenophore showing skeletal
hyphae, gloeocystidia and basidia.