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True Fungi (Eumycophyta) 1
Deuteromycota
– Fungi Imperfecti
(Contact) [CLICK on illustrations to enlarge] Tables Plates
Introduction This group of fungi comprises over 20,000 species and
is very important in breaking down organic matter, as plant and animal
pathogens and for industrial importance.
They are all higher true fungi, which lack a known perfect stage. Their mycelium is like that in the
Ascomycota and vegetative reproduction structures are common to both
groups. Over 90 percent of the
important fungi that have been shown to possess a perfect, or sexual, stage
have been Ascomycota. Most of the
Deuteromycota produce conidia of one kind or another. There is substantial evidence that at
least the majority of these fungi are of Ascomycetous affinities. Indeed, it is probable that a great many
of them are Ascomycota whose perfect stages have simply escaped
discovery. Mycologists continue to
report finding ascigerous stages of several fungi previously included in this
group. Thereafter these drop out of
the Fungi Imperfecti and are renamed and reclassified on the basis of the
newly acquired information. How many
other members of the Fungi Imperfecti will in a similar way ultimately be
eliminated from the group can only be conjectured. However, it seems likely that among the large number of species
at present catalogued as Deuteromycota, there are some that never do produce
a perfect stage, perhaps having lost the ability in the course of evolution,
reproduction by conidia or other vegetative means having proved adequate for
survival. Four orders that will be
discussed here are Sphaeropsidales, Melanconiales, Moniliales and Mycelia
Sterilia. In 1952 Alexopoulos gave a detailed narrative of the
Deuteromycota, and the following description is derived therefrom [Alexopoulos, C. J. 1952.
Introductory Mycology.
John Wiley & Sons, NY. 482
p.]. ------------------------------------- A great many fungi are known which have septate mycelium
and which, so far as anyone has been able to discover, re- produce only by
means of conidia. Since these fungi apparently lack a sexual phase (perfect stage),
we call them commonly "imperfect fungi," and technically
"Fungi Imperfecti." Many of these are saprobic, but many are of
great importance to us because they are parasites that cause diseases of
plants, animals, and human beings.
The same methods employed for the
formation of pycnidia also serve for the formation of. acervuli, the origin
of which may be simple meristogenous, compound meristogenous, or
symphogenous. This undoubtedly explains the fact that intermediate forms,
between pycnidia and acervuli are produced by some fungi which ~re,
therefore, difficult to classify.
------------------------------------- Sphaeropsidales In this order the
spores are borne in a flask-shaped pycnidium on the inside of which are
conidiophores bearing conidia (pycnospores). Four form-families have been distinguished as follows: (1) Sphaeropsidaceae (pycnidia dark colored, leathery
to carbonous, stromatic or non-stromatic generally provided with a circular
opening). (2) Zythiaceae (pycnidia as in
the Sphaeropsidaceae but light colored instead of dark, and soft or waxy
instead of leathery). (3) Leptostromataceae (pycnidia shield-shaped or elongated, flattened). (4) Excipulaceae (mature pycnidia somewhat deeply
cup-shaped). In the family Sphaeropsidaceae species of the
genus Darluca are hyperparasitic on
rusts. Species of Cicinnobolus are hyperparasites of
powdery mildew. Their mycelium is
grown longitudinally in the mycelium of their hosts. ------------------------------------- Please refer to
the following plates for characteristic structures in the Sphaeropsidales: Deuteromycota (Fungi
Imperfecti): Sphaeropsidales Plate 150 = Pycnidia
types: Zythis fragariae, Dendrophoma
abscurans, Chaetomella atra, Diplodia zeae, Fusicoccum viticolum & Endothia
parasitica. Plate 151 = Pycnidial
development: Phoma herbarum, P.
pirina & Zythia fragariae. Plate 153 =
Sphaeropsidales: Pycnidiospore types. Plate 240 = Example Structures: Deuteromycota: Sphaeropsidales:
Sphaerioidaceae ------------------------------------- Melanconiales Spores are borne on
an acervulus in this order (as in the genus Higginsia of the
Ascomycota) Only one form-family has been
designated: Melanconiaceae.
Many species are parasitic on plants and cause a group of diseases
called anthracnoses. The acervuli that are the characteristic
structures of this family usually develop below the cuticle or below the
epidermis of the host plant. They
release their conidia in characteristic droplets, which may be white,
cream-colored, pink, orange or black depending on the pigmentation of the
conidia. In the family Melanconiaceae the genus Gloeosporium has setae, the genus Colletotrichum does not have setae and Cylindrosporium is lit the genus Higginsia
of the Ascomycota: Helotiales. ------------------------------------- Please refer to the following plates for characteristic
structures in the Melanconiales: Deuteromycota (Fungi Imperfecti): Melanconiales Plate 152 =
Acervuli: Gloeosporium sp.
& Colletotrichum lindemuthianum. Plate 154 =
Melanconiales: Conidia types. Plate 241 = Example
Structures: Deuteromycota: Melanconiales & Mycelia Sterilia ------------------------------------- Moniliales This order includes all
the other spore-producing forms and contains the greatest number of
species. Many species are of great
importance and the group contains most of the fungal pathogens of
humans. It is also the group that has
many of the fungi that or of industrial importance. Species of Penicillium and Aspergillus that are
not known to form cleistothecia are included. The so-named "false yeasts" that are not known to
produce ascospores are grouped here.
There are a number of serious plant pathogens as well and some common
contaminants of the biological laboratory and many soil fungi what are
saprobic and may play a significant role in the soil economy. Eight family are included here. The family Stilbaceae has a coremium or synnema. The majority of species are saprobic. The form-genus Graphium
is economically important because several species are responsible
for blue stain of lumber that reduces market value. The imperfect stage of Ophiostoma
ulmi (= Graphium ulmi)
belongs here also. The family Tuberculariaceae has a sporodochium, which is a
cushion-like mass of hyphae. The
genera Tubercularia, Volutella and Fusarium are well
known. In Tubercularia the
sporodochium is usually shaped like a mushroom, with a very short stalk and a
smooth surface. In Volutella the
sporodochium produces setae that arise here and there over the entire fructification. Volutella
fructi causes Dry Rot of Apples. The form-genus Fusarium
is the largest in this family and taxonomically one of the most
difficult of all fungal groups. Fusarium
produces long, crescent-shaped, multiseptate macroconidia usually borne on
sporodochia, and very small spherical, oval elongated or crescent shaped
microconidia on simple or branched single hyphae. Chlamydospores are also regularly produced by the mycelium, and
sclerotia are often formed. Parasitic
species are generally vascular parasites that cause wilts of plants by
plugging the conducting tissues and by toxin secretions. Among the most destructive species are Fusarium
solani on potato, Fusarium cubense on banana and Fusarium
lini on flax (Plate 159). The families Moniliaceae and Dermatiaceae have spores scattered over the
mycelium. The Moniliaceae have
hyaline spores whereas the Dermatiaceae have dark pigmented spores. The genus Thielaviopsis has
endoconidia, but they may also produce macroconidia or chlamydospores in
chains. The Moniliaceae is the larges of
all the form-families. It includes
all imperfect fungi that produce conidia on unorganized, hyaline
conidiophores or directly on the somatic hyphae. Most species are saprobic, but many are important plant
parasites and others are human pathogens.
The imperfect stages of Aspergillus and Penicillium
belong here (Plate 102,f). The family Dermophyta is related to Gymnoascaceae of the
Ascomycota. In the family Cryptococcaceae there are
asporagenous yeasts, which are related to Saccharomyces of the
Ascomycota. The Genus Candida incites a human disease called "Thrush."
The Genus Cryptococcus includes animal
pathogens and Torulopsis is a food yeast that
is used for animal food. The family Rhodotorulaceae is asporagenous yeasts
that are possibly related to the Basidiomycota: Dacryomycetales. The family Sporobolomycetaceae is also
asporagenous yeasts that are possibly related to the Basidiomycota: Dacryomycetales. Sporobolomyces species
have pink or orange-pigmented forms.
They may reproduce by simple budding or they may produce sterigmata
with spores that are shot off forcibly (= ballistospores). ------------------------------------- Please refer to the following plates for characteristic
structures in the Moniliales: Deuteromycota (Fungi Imperfecti): Moniliales Plate 155 = Capsules of Cryptococcus neoformans. Plate 156 = Structures of Candida albicans & Geotrichum
sp. Plate 157 = Budding & spore production: Nectaromyces spp. & Sporobolomyces
spp. Plate 158 = Moniliales:
Conidia types. Plate 159 = Sporodochium of Fusarium lini & Fusarium
sp. Plate 242 = Example Structures: Deuteromycota: Moniliales ------------------------------------- Mycelia Sterilia includes a group of fungi in which no
conidia or other reproductive cells are known. Sclerotia are formed, but there are no fruiting bodies (=
spores). Many of the Mycelia Sterilia
proved to be Basidiomycota when their perfect stages were discovered. Of the over two form-genera in this group,
Rhizoctonia and Sclerotium
are the best known and most widely distributed. Rhizoctonia is usually found in
soils causing damping-off and root rot of their host plants. Pellicularia
filamentosa, a basidiomycete, has Rhizoctonia solani as
its imperfect stage. It causes Black Scurf of potatoes and attacks other plants
as well. Sclerotium cepivorum
known in the form of small black slcerotia produced on white, cottony
hyphae, causes white rot of onions and garlic. Sclerotium rolfsii is omnivorous and can be very
destructive on plants. ------------------------------------- Please refer to the following plates for characteristic
structures in the Mycelia Sterilia: Deuteromycota (Fungi Imperfecti): Mycelia Sterilia Plate 241 = Example
Structures: Deuteromycota: Melanconiales & Mycelia Sterilia ------------------------------------- Recognition Of Tribes And Sub-Tribes The final
subdivision of most of the families into the equivalent of tribes and sub-tribes
is done on the basis of spore form, structure and color, and utilizing the
"Saccardo Spore Sections"
(= Italian mycologist: 1880-1925) with the following possibilities: Amerosporae = spores
1-celled but not long, notstellate, spiral, or filiform Hyalosporae
= spores hyaline Phaeosporae
= spores dark Didymosporae = spores
2-celled, not stellate, spiral, or filiform Hylodidymae
= spores hyaline Phaeodidymae
= spores dark Phragmosporae = spores more
than 2-celled (variable), not stellate, spiral, or filiform Hyalophragmiae = spores hyaline Phaeophragmiae = spores dark Scoloecosporae = spores long
and slender (scolecospores) septate or non-septate Dictyosporae = spores
muriform Hyalodictyae
= spores hyaline Phaeodictyae =
spores dark Helicosporae = spores
spirally coiled, continuous or septate Staurosporae = spores
stellate (star-shaped) or radiate, continuous or septate ======================== |