This document outlines Ainsworth's 1973 classification system for fungi. It proposes the kingdom Mycota, divided into the divisions Myxomycota (slime molds) and Eumycota (true fungi). Eumycota is further divided into several subdivisions including Mastigomycotina, Zygomycotina, Ascomycotina, Basidiomycotina, and Deuteromycotina. Each subdivision contains multiple classes and orders of fungi classified based on characteristics like cell structure, life cycle stages, and reproductive structures. The classification aims to group fungi based on morphology and natural relationships rather than previous artificial systems.
1. Classification of Fungi
by Ainsworth G. C. (1973)
V.S.Patil
Associate Professor, Department of Botany
Shri Shivaji College of Arts, Commerce,&
Science Akola
2. • Ainsworth G. C. (1966, 71, 73) proposed a more
natural system of classification of fungi. This
classification is based on morphology, especially of
reproductive structure.
3.
4. • Ainsworth G. C includes fungi along with slime
molds under the kingdom Mycota. Based on the
presence or absence of Plasmodium and
pseudoplasmodium; the kingdom Mycota is
further divided into two divisions:
• Myxomycota i.e., slime molds and Eumycota or
true fungi. Divisions are subsequently divided
into subdivision, class, subclass, order, family and
then to genus. According to his classification,
division ends in mycota, subdivision in mycotina,
class in mycetes, subclass in mycetidae order in
ales and family in aceae.
5. .
A schematic outline of Ainsworth’s (1973) classification
is given:
Kingdom: Mycota
Important features:
i. Free-living, parasitic or mutualistic symbionts, devoid
of chlorophyll.
ii. Cell wall composition is very variable, majority contain
chitin and glucan.
iii. Reserve food materials are oil, mannitol and glycogen.
iv. Except some unicellular members, majority are
filamentous
6. A. Division. Myxomycota:
Wall-less organisms possess either a Plasmodium (a mass
of naked multinucleate protoplasm having amoeboid
movement) or a pseudoplasmodium (an aggregation of
separate amoeboid cells). Both are of slimy consistency,
hence slime molds.
1. Class. Acrasiomycetes (cellular slime molds)
2. Class. Hydromyxomycetes (net slime molds)
3. Class. Myxomycetes (true slime molds)
4. Class. Plasmodiophoromycetes (endo- parasitic slime
molds).
7. B. Division Eumycota (True fungi, all with walls):
a. Subdivision Mastigomycotina (motile cells –
zoospores present, perfect state spore-oospore).
1. Class. Chitridiomycetes (unicellular, zoospore with
single whiplash flagellum).
2. Class. Hyphochytridiomycetes (unicellular, zoospore
with single tinsel flagellum).
3. Class. Oomycetes (aseptate mycelium, zoospores with
two flagella).
b. Subdivision. Zygomycotina (mycelium aseptate,
perfect state spore-zygospore).
1. Class. Zygomycetes (mycelium immersed in the host
tissue).
2. Class. Trichomycetes (mycelium not immersed in the
host tissue).
8. c. Subdivision. Ascomycotina (yeasts or septate mycelium,
perfect state spore- ascospores formed in ascus, usually
within ascocarp).
1. Class. Hemiascomycetes (no ascocarp, asci naked).
2. Class. Loculoascomycetes (fruit body an ascostroma,
asci bitunicate i.e., 2-walled).
3. Class. Plectomycetes (fruit body cleistothecium, asci
unitunicate i.e., 1-walled).
4. Class. Laboulbeniomycetes (fruit body perithecium,
asci unitunicate, exoparasite of arthopods).
5. Class. Pyrenomycetes (fruit body perithecium, asci
unitunicate, not parasitic on arthopods.
6. Class. Discomycetes (fruit body apothecium, asci
unitunicate).
9. d. Subdivision. Basidiomycotina (yeast or septate
mycelium, perfect state spore – basidiospore formed on a
basidium).
1. Class. Teliomycetes. Basidiocarp lacking, teliospores
grouped in sori or scattered within the host tissue, parasitic
on vascular plant.
2. Class. Hymenomycetes. Basidio- carp present.
Hymenium is completely or partly exposed at maturity.
Basidiospore ballistospores.
3. Class. Casteromycetes. Basidiocarp present. Hymenium
enclosed in basidiocarp. Basidiospore not ballistospores.
10. (e) Subdivision. Deuteromycotina or Fungi imperfecti.
Yeast or septate mycelium. Perfect state unknown.
1. Class. Blastomycetes. Budding (Yeast or Yeast like)
cells with or without pseudomycelium. True mycelium
lacking or not well-developed.
2. Class. Hyphomycetes. Mycelia sterile or bearing
asexual spore directly or on conidiophore, in various
aggregation.
3. Class. Coelomycetes. Mycelial; asexual spore formed
in pycnidium or acervulus.
13. Kingdom Mycota (fungi)
Eukaryotic (with true nuclei), achlorophyllous (without chlorophyll),
acellular, unicellular, or multicellular organisms; microscopic or
macroscopic in size; usually with cell walls and filaments; typically
reproducing by spores produced asexually or sexually; walls containing
chitin, cellulose, or both, among other substances; about 50,000 living
species; fewer than 500 fossil species known.
Division Eumycota (true fungi)
Assimilative stage walled, typically filamentous (a mycelium),
sometimes unicellular, usually eucarpic (having only part of the thallus
forming a fruiting structure); asexual reproduction by fission, budding,
fragmentation, or, more typically, by spores; sexual reproduction by
various means, usually resulting in the formation of resting structures or
meiospores.
14. Class Chytridiomycetes
Unicellular or filamentous, holocarpic (having all of the thallus involved in the
formation of the fruiting body) or eucarpic; motile cells (zoospores or
planogametes) characterized by a single, posterior, whiplash flagellum; mostly
aquatic fungi saprobic or parasitic on algae, fungi, or, less often, on flowering
plants.
Order Chytridiales
Mycelium lacking but rhizoids (short absorbing filaments) or rhizomycelium often
present; chiefly freshwater saprobes or parasites of algae and fungi; some terrestrial
species, such as Olpidium brassicae and Synchytrium endobioticum, cause plant
disease; about 550 species.
Order Blastocladiales
Water molds with a restricted thallus, characterized by the production of thick-
walled, pitted, resistant sporangia; sexual reproduction by isogamous (equal in size
and alike in form) or anisogamous (unequal in size but still similar in form)
planogametes; Allomyces exhibits an alternation of 2 equal generations; most are
saprobes, but various species of Coelomomyces are parasitic in mosquito larvae;
uniquely, their hyphae are devoid of cell walls; more than 50 species.
Order Monoblepharidales
Water molds with an extensive, foamy mycelium; sexual reproduction by a motile
male gamete (antherozoid) fertilizing a nonmotile differentiated egg, resulting in a
thick-walled oospore; about 20 species
15. . Class Hyphochytridiomycetes
A small group of mostly marine fungi very similar to the order
Chytridiales but with motile cells bearing a single tinsel flagellum
(i.e., a flagellum with short side branches along the central axis,
comblike).
Order Hyphochytriales
Characters of the class; about 15 species.
Class Plasmodiophoromycetes
Endoparasites (internal parasites) of fungi or plants often causing
hypertrophy (excessive abnormal growth); assimilative stage an
endophytic (living within plant tissue) plasmodium that becomes
converted into a group of zoosporangia (structures producing motile
asexual spores) or a large number of small, walled spores; motile
cells with 2 unequal, anterior, whiplash flagella
Order Plasmodiophorales
Characters of the class; Plasmodiophora and Spongospora cause
serious plant diseases; about 35 species.
16. .
Class Oomycetes
Aquatic, amphibious, or terrestrial fungi; saprobic, facultatively (occasionally) or obligately
(invariably) parasitic on plants, a few on fish; asexual reproduction typically by zoospores with 2
anterior or lateral flagella, 1 whiplash, 1 tinsel; sexual reproduction usually by contact of
differentiated gametangia (gamete- or sex-cell-producing structures) with nuclei from the male
fertilizing differentiated eggs and resulting in thick-walled oospores; thallus probably diploid
with meiosis occurring in the gametangia
Order Lagenidiales
Holocarpic, unicellular or filamentous water molds, parasitic on algae and fungi or saprobic;
oogonium (egg-producing structure) typically containing a single egg; about 85 species.
Order Saprolegniales
Mostly eucarpic, filamentous water molds or soil fungi; saprobic or parasitic; hyphae without
constrictions or cellulin plugs; oogonia containing 1 to many free eggs; some species are
diplanetic, i.e., they produce 2 types of zoospores, primary (pear-shaped with anterior flagella)
and secondary (kidney-shaped with lateral flagella); some (Aphanomyces) cause root rots; others
(Saprolegnia) infect fish and fish eggs; about 200 species.
Order Leptomitales
Aquatic saprobes found often in polluted waters; eucarpic; hyphae constricted, with cellulin
plugs, arising from a well-defined basal cell; oogonium typically containing a single egg, which
may be free or embedded in periplasm (a peripheral layer of protoplasm); 20 species.
Order Peronosporales
Aquatic or terrestrial; parasitic on algae or vascular plants, the latter mostly obligate parasites
causing downy mildews; zoosporangia, in advanced species, borne on well-differentiated
sporangiophores, deciduous and behaving as conidia (asexually produced spores); about 250
species.
17. .
Class Zygomycetes
Terrestrial saprobes or parasites of plants, animals, or humans; asexual
reproduction by aplanospores (nonmotile spores) in sporangia or by conidia;
sexual reproduction by fusion of morphologically similar gametangia, sometimes
differing in size, resulting in thick-walled zygospores.
Order Mucorales
Often called the bread molds; saprobic, weakly parasitic on plants, or parasitic on
humans and then causing mucormycosis (a pulmonary infection); asexual
reproduction by sporangiospores, 1-spored sporangiola (a small deciduous
sporangium), or conidia; in the genus Pilobolus the heavily cutinized sporangium
is forcibly discharged; about 360 species.
Order Entomophthorales
Insect parasites or saprobes, some implicated in animal or human diseases;
asexual reproduction by modified sporangia functioning as conidia, forcibly
discharged; about 150 species.
Order Zoopagales
Parasitic on amoebas, rotifers, nematodes, or other small animals, which they trap
by various specialized mechanisms; asexual reproduction by conidia borne singly
or in chains, not forcibly discharged; about 60 species.
18. Class Trichomycetes
Commensals (organisms living parasitically on another organism but conferring some
benefit in return, or at least not harming the host) with a filamentous thallus attached by
a holdfast or basal cell to the digestive tract or external cuticle of living arthropods;
asexual reproduction by sporangiospores (a spore borne within a sporangium),
trichospores (zoospores or ciliated spores), arthrospores (a spore resulting from
fragmentation of a hypha), or amoeboid cells; sexual reproduction, where known,
zygomycetous.
Order Amoebidiales
Thallus coenocytic (without cross walls, with numerous freely distributed nuclei)
arising from a holdfast; amoeboid cells formed; about 12 species.
Order Eccrinales
Thallus coenocytic, attached by a holdfast to the digestive tract of arthropods;
aplanosporangia produced in succession; more than 50 species.
Order Asellariales
Thallus branched, septate, attached by a basal coenocytic cell; asexual reproduction by
arthrospores; 6 species.
Order Harpellales
Thallus simple or branched, septate; asexual reproduction by trichospores; sexual
reproduction zygomycetous; about 35 species.
19. Class Ascomycetes
Saprobic or parasitic on plants, animals, or humans; some are
unicellular but most are filamentous, the hyphae septate with
1, rarely more, perforations in the septa; cells uninucleate or
multinucleate; asexual reproduction by fission, budding,
fragmentation, or, more typically, by conidia usually produced
on special sporiferous (spore-producing) hyphae, the
conidiophores, which are borne loosely on somatic (main-
body) hyphae or variously assembled in asexual fruiting
bodies; sexual reproduction by various means resulting in the
production of meiosphores (ascospores) formed by free-cell
formation in saclike structures (asci), which are produced
naked or, more typically, are assembled in characteristic open
or closed fruiting bodies (ascocarps); among the largest and
most commonly known ascomycetes are the morels, cup fungi,
saddle fungi, and truffles.
20. Subclass Hemiascomycetidae
Asci naked, formed from single cells or on hyphae; no ascocarps
or ascogenous hyphae produced; saprobic or parasitic.
Order Protomycetales
Spore sac compound (a synascus); a poorly known small group of
plant-parasitic ascomycetes; 20 or more species.
Order Endomycetales
Mostly saprobic, a few parasitic; zygote or single cell transformed
directly into the ascus; mycelium sometimes lacking; this group
includes the yeasts and their relatives.
Order Taphrinales
Parasites on vascular plants; asci produced from binucleate
ascogenous (ascus-producing) cells formed from the hyphae in the
manner of chlamydospores (thick-walled spores); 90 or more
species.
21. Subclass Euascomycetidae
Asci unitunicate (ascus wall single-layered), borne in various types of ascocarps;
saprobic or parasitic on plants, animals, or humans.
Order Eurotiales
Asci globose to broadly oval, typically borne at different levels in cleistothecia
(completely closed ascocarp or fruiting structure); most of the human and animal
dermatophytes belong here, also many saprobic soil or coprophilous fungi; possibly up to
150 species.
Order Microascales
Asci evanescent (quickly deteriorating), borne at different levels in perithecia (closed
ascocarps with a pore in the top) with ostioles (the opening of the perithecium), or
sometimes a long necklike structure terminating in a pore; some serious plant parasites
such as Ceratocystis ulmi (Dutch elm disease) and C. fagacearum (oak wilt) belong here;
about 100 species.
Order Onygenales
Asci formed in a mazaedium (a fruiting body consisting of a powdery mass of free spores
interspersed with sterile threads, enclosed in a peridium or wall structure), evanescent,
and liberating the ascospores as a powdery mass among sterile threads; about 25 species.
Order Erysiphales
Obligate parasites on flowering plants causing powdery mildews; mycelium white,
superficial in most, feeding by means of haustoria sunken into the epidermal cells of the
host; 1 to several asci in a cleistothecium, if more than 1, in a basal layer at maturity; asci
globose to broadly oval; cleistothecia with appendages; about 150 species.
22. Order Meliolales
Mycelium dark, superficial on leaves and stems of vascular plants, typically bearing
appendages (termed hyphopodia or setae); asci in basal layers in ostiolate perithecia
without appendages; mostly tropical fungi; more than 1,000 species.
Order Chaetomiales
Asci in basal layers in superficial perithecia that bear conspicuous, straight or curly,
simple or branched hairs on the surface; asci evanescent; about 110 species.
Order Xylariales
Perithecia with dark, membranous or carbonous (appearing as black burned wood)
walls, with or without a stroma (a compact structure on or in which fructifications
are formed); asci persistent, borne in a basal layer among paraphyses (elongate
structures resembling asci but sterile), which may ultimately gelatinize and
disappear; a rather large group of fungi one of which, Neurospora crassa, has been
used extensively in genetic and biochemical studies; approximately 4,500 species.
Order Diaporthales
Perithecia immersed in plant tissue or in a stroma with their long ostioles protruding;
ascal stalks gelatinizing, freeing the asci from their basal attachment; paraphyses
lacking; the chestnut blight fungus (Endothia parasitica) belongs here; close to 500
species.
Order Hypocreales
Perithecia and stromata when present, brightly coloured, soft, fleshy, or waxy, when
fresh; asci borne in a basal layer among apical paraphyses; about 800 species.
23. Order Clavicipitales
Perithecia immersed in a stroma that issues from a sclerotium (a hard-
resting body resistant to unfavourable environmental conditions); asci
with a thick apex penetrated by a central canal through which the
septate, threadlike ascospores are ejected; the ergot fungus (Claviceps
purpurea), cause of ergotism in plants, animals, and humans, and the
original source of LSD, belongs to this order; some other
Clavicipitales parasitize insect larvae; about 170 species.
Order Coryneliales
Asci in ascostromata with funnel-shaped ostioles at maturity; about
20 species.
Order Coronophorales
Asci in ascostromata with irregular or round, never funnel-shaped,
openings; about 30 species.
Order Laboulbeniales
Ascomycetes of uncertain affinity; minute parasites of insects and
arachnids with mycelium represented only by haustoria and stalks;
about 1,635 species.
24. Order Ostropales
Ascocarp a loculelike apothecium (an open, often cuplike ascocarp); asci
inoperculate (without a terminal pore) constructed as in the Clavicipitales;
ascospores septate, threadlike; about 80 species.
Order Phacidiale
Ascocarp an apothecium immersed in a black stroma, the upper covering of
which splits in stellate (star-shaped) or irregular fashion when ascospores mature;
about 150 species.
Order Helotiales
Ascocarp an apothecium bearing inoperculate asci exposed from an early stage;
some important plant diseases are caused by members of this group (for
example, Monilinia fructicola causes brown rot of stone fruits), the earth tongues
(Geoglossaceae) also belong here; more than 1,500 species.
Order Pezizales
Ascocarp an apothecium bearing operculate (with a hinged cap) asci above the
ground; apothecia often large, cup- or saucer-shaped, spongy, brainlike, saddle-
shaped, etc.; this group includes the morels, the false morels, and the saddle fungi
among others; about 700 species.
25. Order Tuberales (truffles)
The ascocarps, mostly closed and borne below the ground, are considered to be
modified apothecia; the asci are globose, broadly oval, or club-shaped; about 230
species.
Subclass Loculoascomycetidae
Asci bitunicate, borne in ascostromata; saprobic or parasitic on plants.
Order Myriangiales
Asci borne singly in locules arranged at various levels in a more or less globose
stroma; about 100 species.
Order Dothideales
Asci borne in fascicles (clusters) in a locule devoid of sterile elements; about 600
species.
Order Pleosporales
Asci borne in a basal layer among pseudoparaphyses; more than 2,000 species.
Order Microthyriales
Stroma flattened, hemispherical, opening by a pore or tear; base usually lacking;
asci borne among pseudoparaphyses; mostly tropical fungi; about 1,200 species.
Order Hysteriales
Stroma boat-shaped, opening by a longitudinal slit, which renders it apothecium-
like; asci borne among pseudoparaphyses; about 110 species.
26. Class Basidiomycetes
Saprobic or parasitic on plants or insects; filamentous; the hyphae septate, the septa
typically inflated (dolipore) and centrally perforated; mycelium of 2 types, primary
of uninucleate cells, succeeded by secondary, consisting of dikaryotic cells, this
often bearing bridgelike clamp connections over the septa; asexual reproduction by
fragmentation, oidia (thin-walled, free, hyphal cells behaving as spores), or conidia;
sexual reproduction by fusion of hyphae (somatogamy), fusion of an oidium with a
hypha (oidization), or fusion of a spermatium (a nonmotile male structure that
empties its contents into a receptive female structure during plasmogamy—a kind of
gamete) with a specialized receptive hypha (spermatization), resulting in dikaryotic
hyphae that eventually give rise to basidia, either singly on the hyphae or in
variously shaped basidiocarps; meiospores (basidiospores) borne on basidia; in the
rusts (Uredinales) and smuts (Ustilaginales), the dikaryotic hyphae produce
teleutospores (thick-walled resting spores), which are a part of the basidial
apparatus; this is a large class of fungi containing the rusts, smuts, jelly fungi, club
fungi, coral and shelf fungi, mushrooms, puffballs, stinkhorns, and bird’s-nest fungi
27. Subclass Heterobasidiomycetidae
Basidia septate or deeply divided or arising from a teleutospore or cyst; basidiospores
often germinating by repetition, budding, or production of conidia; includes the jelly
fungi, the rusts, and the smuts.
Order Tremellales (jelly fungi)
Fruiting bodies (basidiocarps) well-formed, appearing as inconspicuous horny crusts
when dry but usually bright-coloured to black gelatinous masses after a rain; a few are
parasitic on mosses, vascular plants, or insects; most are saprobes; about 500 species.
Order Uredinales (rusts)
Parasitic on vascular plants; basidial apparatus consists of a thick-walled teleutospore
(probasidium), which either gives rise to a 4-celled tube (metabasidium) on which
basidiospores are borne or which itself becomes 4-celled and produces basidiospores
directly; basidiospores forcibly discharged; many rusts are heteroecious, i.e., they require
2 species of host to complete their life cycle; rusts are among the fungi most destructive
to agriculture; about 4,600 species.
Order Ustilaginales (smuts)
Called smuts because the masses of spores (sori) are usually black and dusty; basidial
apparatus consisting of a thick-walled teleutospore (probasidium), which, upon
germination, gives rise to a septate or nonseptate tube (metabasidium), which bears the
basidiospores; basidiospores not forcibly discharged, germinating usually by budding or
by fusing and then producing a mycelial germ tube; various cereal smuts are of great
economic importance; about 700 species.
28. Subclass Homobasidiomycetidae
Includes the great majority of the Basidiomycetes; most produce conspicuous,
large-fruiting bodies, which bear the spores on basidia; basidia are simple,
cylindrical, or club-shaped; basidiospores, which may or may not be forcibly
discharged, germinate directly into a mycelium.
Order Exobasidiales
Basidiocarps lacking; basidia produced in a layer on the surface of parasitized
vascular plants; 15 species.
Order Polyporales
Basidiocarps present; a large and probably heterogeneous order of fungi in which
the basidia are borne in various ways but rarely on gills; includes the coral fungi,
the club fungi, the chanterelles, and the pore (shelf or bracket) fungi among
others; common genera
include Stereum, Clavaria, Hydnum, Cantharellus, Polyporus, Fomes; Schizophyl
lum has been used extensively for genetic research; up to 2,500 species.
Order Agaricales (mushrooms and boletes)
Basidia produced in layers (hymenia) on the underside of fleshy fruiting bodies
(basidiocarps), in tubes (boletes) or on gills (mushrooms); some of these fungi
form mycorrhizae, some are parasitic and cause root rots; most are saprobic;
4,000 to 5,000 species.
29. Order Hymenogastrales
Basidiocarps underground or on the surface but usually buried in humus,
remaining closed, the interior (gleba) disintegrating into a slimy mass containing
the spores; about 225 species.
Order Lycoperdales (puffballs)
Gleba dry and powdery at maturity; consisting of small, pale spores and well-
developed capillitium; about 160 species.
Order Sclerodermatales
These are puffballs with a hard peridium enclosing a dry, powdery gleba
consisting of large, dark spores and some capillitium; about 120 species.
Order Phallales (stinkhorns)
Gleba slimy and fetid at maturity; exposed on an elongated or net-shaped
receptacle; Phallus, Mutinus, Dictyophora, Simblum, Clathrus are temperate-zone
genera; about 70 species.
Order Nidulariales (bird’s-nest fungi)
The gleba separates into chambers, which become thick-walled, waxy, and hard—
these are the peridioles (“eggs”), which are evident within a cuplike or gobletlike
basidiocarp, the whole resembling a bird’s nest at maturity—
Cyathus and Crucibulum are the 2 most widely distributed genera; about 60
species.
30. Form-class Deuteromycetes
Fungi with septate mycelium reproducing only asexually
and resembling asexual stages of Ascomycetes and
Basidiomycetes.
Form-order Sphaeropsidales
Conidia borne in pycnidia; about 5,500 species.
Form-order Melanconiales
Conidia borne in acervuli; about 1,000 species.
Form-order Moniliales
Conidia borne on variously assembled conidiophores but
never in pycnidia or acervuli; 10,000 or more species.
Form-order Mycelia Sterilia
No conidia produced; probably mycelial stages of
Basidiomycetes; about 200 species.
