''Exserohilum'' is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
in the family
Pleosporaceae
Pleosporaceae is a family of sac fungi. The taxonomic relationship of this family to associated genera is still not determined.
Genera
As accepted by GBIF;
* '' Acrothecium'' (13)
* ''Alternaria'' Nees ex Wallroth, 1816 (841)
* '' Alternariast ...
. The ''Exserohilum'' species are known for causing blight and human immune system diseases. The sexual reproductive (or
ascigerous) states of Exserohilum species are known as
Setosphaeria
''Setosphaeria'' is a genus of fungi in the family Pleosporaceae
Pleosporaceae is a family of sac fungi. The taxonomic relationship of this family to associated genera is still not determined.
Genera
As accepted by GBIF;
* '' Acrothecium'' ...
. The
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
is ''
Exserohilum turcicum
''Setosphaeria turcica'' (anamorph ''Exserohilum turcicum''; formerly known as ''Helminthosporium turcicum'') is the causal agent of northern corn leaf blight in maize. It is a serious fungal disease prevalent in cooler climates and tropical hig ...
''. This genus is among three
dematiaceous
“Black yeasts”, sometimes also black fungi, dematiaceous fungi, microcolonial fungi or meristematic fungi is a diverse group of slow-growing microfungi which reproduce mostly asexually (fungi imperfecti). Only few genera reproduce by budding ...
that are categorized for containing
pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...
s leading to diseases like
phaeohyphomycosis
Phaeohyphomycosis is a diverse group of fungal infections, caused by dematiaceous fungi whose morphologic characteristics in tissue include hyphae, yeast-like cells, or a combination of these. It can be associated an array of melanistic filamento ...
.
Morphology
''Exserohilum'' is an
asexual organism that reproduces through
spores. These one-celled reproductive units are concave and can be seen in the
suspensor
Suspensors are anatomical structures found in certain fungi and plants.
Fungi
In fungi, suspensors are filamentous structural formations having the function of holding a zygospore between two strains of hyphae.
Plants
In plants, suspensors are ...
.
Taxonomy
''Exserohilum'' was
circumscribed
In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius.
Not every polyg ...
by K. Leonard and Edna Suggs in 1974 to contain species formerly placed in ''
Bipolaris'' with distinctly protruding
hila.
Exsero which means stretch out and
hilum which refers to the part of the organism. The truncate hila or hilum, protrudes from its distinct
conidia
A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to the ...
which are
ellipsoid
An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation.
An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...
al and distoseptate (forming a layer).
Colonies of ''Exserohilum'' range from the color grey to blackish-brown. The texture varies from suede-like to floccose in texture. The species also have an olivaceous to black reverse. The conidia from which the hilum extends, are either straight, curved, slightly bent or ellipsoidal to fusiform. and are formed on the top through a pore (poroconidia) on an elongated
sympodial angled
conidiophore. The strong, protruding truncate hilum and the septum above is normally thick and dark. The end cells are paler and the walls finely roughened. The conidial germination of ''Exserohilum'' is bipolar.
Habitat and distribution
''Exserohilum'' has a
cosmopolitan distribution
In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in appropriate habitats. Such a taxon, usually a species, is said to exhibit cosmopolitanism or cosmopolitism. The ext ...
, with its species found naturally in warm,
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
, and
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...
locations. They live on plant material like grasses, rotten wood and in the soil.
Species
,
Index Fungorum lists 26 valid species of ''Exserohilum'':
*''
Exserohilum antillanum
''Exserohilum antillanum'' is a species of fungus in the family Pleosporaceae. Found in Cuba growing on plant debris, it was described as new to science in 1995. The specific epithet ''antillanum'' refers to the Antillian sea, an old name for th ...
'' R.F.Castañeda, Guarro & Cano 1995 – Cuba
*''
Exserohilum curvatum
''Exserohilum curvatum'' is a species of fungus in the family Pleosporaceae. Found in Venezuela, where it grows on the leaves of ''Sorghum'', it was described as new to science in 1984. It differs from other ''Exserohilum'' species by its distin ...
'' Sivan. & Muthaiyan 1984 – Venezuela
*''
Exserohilum curvisporum'' Sivan., Abdullah & B.A.Abbas 1993 – Iraq
*''
Exserohilum echinochloae'' Sivan. 1984 – Bangladesh
*''
Exserohilum frumentacei'' (Mitra) K.J.Leonard & Suggs 1974 –
Andhra Pradesh
Andhra Pradesh (, abbr. AP) is a state in the south-eastern coastal region of India. It is the seventh-largest state by area covering an area of and tenth-most populous state with 49,386,799 inhabitants. It is bordered by Telangana to the ...
;
Bihar
Bihar (; ) is a state in eastern India. It is the 2nd largest state by population in 2019, 12th largest by area of , and 14th largest by GDP in 2021. Bihar borders Uttar Pradesh to its west, Nepal to the north, the northern part of West Be ...
;
Botswana
Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label=Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalahar ...
;
Ethiopia
Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...
;
Sabah
Sabah () is a States and federal territories of Malaysia, state of Malaysia located in northern Borneo, in the region of East Malaysia. Sabah borders the Malaysian state of Sarawak to the southwest and the North Kalimantan province of Indone ...
*''
Exserohilum fusiforme'' Alcorn 1991 – Queensland
*''
Exserohilum gedarefense'' (El Shafie) Alcorn 1983 – Egypt; Sudan
*''
Exserohilum heteromorphum'' G.Y.Sun 2005
*''
Exserohilum heteropogonicola'' Sivan. 1984 –
Colombia
Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
;
Uttaranchal
Uttarakhand ( , or ; , ), also known as Uttaranchal ( ; the official name until 2007), is a state in the northern part of India. It is often referred to as the "Devbhumi" (literally 'Land of the Gods') due to its religious significance and ...
*''
Exserohilum inaequale'' Sivan. 1984 – Nigeria
*''
Exserohilum israeli'' Steiman, Guiraud, Seigle-Mur. & Sage 2000 – Israel
*''
Exserohilum longirostratum'' (Subram.) Sivan. 1984 – Andhra Pradesh;
Florida
Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
; France; Haryana;
Madhya Pradesh; Nigeria; Northern Territory;
Puerto Rico
Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...
;
Rajasthan
Rajasthan (; lit. 'Land of Kings') is a state in northern India. It covers or 10.4 per cent of India's total geographical area. It is the largest Indian state by area and the seventh largest by population. It is on India's northwestern si ...
; Sudan; Uttar Pradesh; Zambia
*''
Exserohilum longisporum'' G.Y.Sun 1997 – China
*''
Exserohilum mcginnisii'' A.A.Padhye & Ajello 1986
*''
Exserohilum minor'' Alcorn 1986
*''
Exserohilum neoregeliae'' Sakoda & Tsukib. 2011
*''
Exserohilum oryzae'' Sivan. 1987 – Macedonia
*''
Exserohilum oryzicola'' Sivan. 1984
*''
Exserohilum oryzinum'' Sivan. 1984 – Egypt
*''
Exserohilum parlierense'' W.Q.Chen & Michailides 2002
*''
Exserohilum paspali'' J.J.Muchovej & Nesio 1987 –
Minas Gerais
Minas Gerais () is a state in Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo Horizonte (literally ...
*''
Exserohilum phragmitis'' W.P.Wu 1990
*''
Exserohilum protrudens'' Alcorn 1988
*''
Exserohilum psidii'' Sivan. 1992 – Andhra Pradesh
*''
Exserohilum sodomii'' Guiraud, Steiman, Seigle-Mur. & Sage 1997 – Israel
*''
Exserohilum sorghicola'' Sivan. 1987 – Ethiopia
Clinical significance
Infection cases caused by exposure to ''Exserohilum'' are rare, but it's the most well studied detail of the fungi. The three species of ''Exserohilum'' that are identified as human pathogens are: ''
Exserohilum Rostratum
''Setosphaeria rostrata'' is a heat tolerant fungus with an asexual reproductive form (anamorph) known as '' Exserohilum rostratum''. This fungus is a common plant pathogen, causing leaf spots as well as crown rot and root rot in grasses. It is ...
'', ''
Exserohilum longirostratum'' and ''
Exserohilum mcginnisii''. Prevailing infections include sinusitis, skin infection and in some rare cases, cerebral abscesses, keratitis, osteomyelitis, prothetic valve endocarditis, and disseminated infection. Reports of human infection by ''Exserohilum'' mainly come from warm, tropical and subtropical locations such as southern United States, India, and Israel.
References
External links
{{Taxonbar, from=Q10493219
Dothideomycetes genera
Pleosporaceae