Introduction to Fungi, Third Edition

486 LOCULOASCOMYCETES
Fig17.24 Cladosporium fulvum. Symptoms on
greenhouse-grown tomato leaves as seen from above.
The pale leaf areas are chlorotic spots, at the underside of
which a pale greyish-brown felt of conidiophores is produced.
Fig17.25 Aureobasidium pullulans. (a) Blastoconidia developing
from an undifferentiated hypha. Several conidia can form
from the same point, i.e. conidiogenesis is polyblastic.
(b) Thick-walled melanized chlamydospores formed from
hyphal segments in an older agar culture.
a low-calorie ingredient of foodstuffs and in
pharmaceutical applications (Deshpande et al.,
1992; Leathers, 2003).
Aureobasidium is a member of a group loosely
called black yeasts. This is not a taxonomic term
but simply describes melanized fungi which
produce yeast states, especially in culture.
Several species of black yeasts, notably species
of Exophiala, Cladophialophora and Ramichloridium,
are known as opportunistic human pathogens
causing infections of the brain and other organs
which can be fatal (Horré & de Hoog, 1999; de
Hoog et al., 2000b). The microscopic features
of these species have been described by de
Hoog (1977) and, together with supplementary
information, in an excellent compendium by
de Hoog et al. (2000a). Although formerly considered
to belong to the Loculoascomycetes, they
are now recognized to be related to Capronia
which is grouped in the Chaetothyriales (Haase
et al., 1999; Untereiner, 2000), an order quite
remote from the Loculoascomycetes but with
possible affinities with Plectomycetes or
Lecanorales (Winka et al., 1998). Black yeasts
belonging to the Chaetothyriales are similar to
those of the Dothideales not only in microscopic
features, but also in their ecology,
commonly occurring on living and decaying
vegetation.