''Smittium'' is a genus of fungi in the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Harpellales. It is the largest genus in the order. As of 2013, there were 81 described species.Wang, Y., et al. (2013)
Overview of 75 years of ''Smittium'' research, establishing a new genus for ''Smittium culisetae'', and prospects for future revisions of the ‘Smittium’ clade.
''Mycologia'' 105(1) 90-111. Many of these have been formally described only recently; in 1998 there were just 46.Lichtwardt, R. W. and R. D. Grigg. (1998)
Four new ''Smittium'' species inhabiting the hindgut of Chironomidae larvae.
''Mycologia'' 90(3) 427-33. Several have been transferred to ''Smittium'' from other genera, such as '' Orphella'', '' Rubetella'', '' Genistella'', and '' Typhella''.Valle, L. G. and S. Santamaria. (2004)
The genus ''Smittium'' (Trichomycetes, Harpellales) in the Iberian Peninsula.
''Mycologia'' 96(3) 682-701. In general, the genus 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 ...

, but some species are limited to small regions. Like most other fungi of the Harpellales, these are found in the guts of insect larvae. ''Smittium'' are most often resident in the larvae of aquatic flies. The genus was named for '' Smittia'', the

midge A midge is any small fly, including species in several families of non-mosquito Nematoceran Diptera. Midges are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zones. Some mid ...

from which it was first isolated. The fungi can be found in

black flies A black fly or blackfly (sometimes called a buffalo gnat, turkey gnat, or white socks) is any member of the family Simuliidae of the Culicomorpha infraorder. It is related to the Ceratopogonidae, Chironomidae, and Thaumaleidae. Over 2,200 speci ...

, mosquitoes, solitary midges, and non-biting and

biting midges Ceratopogonidae is a family of flies commonly known as no-see-ums, or biting midges, generally in length. The family includes more than 5,000 species, distributed worldwide, apart from the Antarctic and the Arctic. Ceratopogonidae are holome ...

. The relationship between the fungus and the fly is usually commensal. Sometimes it is more mutualistic, such as when the fungus synthesizes vitamins or other nutrients for the host.Lichtwardt, R. W. Gut fungi of invertebrates. In: Nadkarni, O. N. M. and N. T. Wheelwright, Eds. ''Monteverde: Ecology and Conservation of a Tropical Cloud Forest''. Oxford University Press. 2000. pg. 83. One species, though, '' Smittium morbosum'', can best be described as parasitic on its mosquito larva host, killing it by preventing it from

molting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

. No other gut fungi are known to be lethal to their hosts in this way. The host larva is infected with ''Smittium'' when it ingests the fungal

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

.Vojvodic, S. and J. W. McCreadie. (2008)
Do different species of ''Smittium'' (Harpellales, Legeriomycetaceae) influence each other in the host gut?
''Mycological Research'' 112 1409-13. ''Smittium'' generally live in the

hindgut The hindgut (or epigaster) is the posterior ( caudal) part of the alimentary canal. In mammals, it includes the distal one third of the transverse colon and the splenic flexure, the descending colon, sigmoid colon and up to the ano-rectal juncti ...

of the fly larva, attaching to the

chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...

ous gut lining via a

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

. When the fungus produces spores, they are excreted by the host. Sometimes several species can be found in the gut flora of one host. '' S. brevisporum'', '' S. bulbosporophorus'', and '' S. inexpectans'' have been noted growing together, for example. Other genera of gut fungi can be present, as well, such as '' Genistellospora''.Ríos-Velásquez, C. and N. Hamada. (2002)
Trichomycete fungi (Zygomycota) associated with the digestive tract of ''Simulium goeldii'' Cerqueira & Nunes de Mello and ''Simulium ulyssesi'' (Py-Daniel & Coscarón) (Diptera: Simuliidae) larvae, in Central Amazônia, Brazil.
''Memórias do Instituto Oswaldo Cruz'' 97(3) 423-26. Some ''Smittium'' can be found in a number of hosts, while others are more host-specific. '' S. heterosporum'' has been collected from nonbiting midges of the genera ''

Sympotthastia ''Sympotthastia'' is a genus of non-biting midges in the subfamily Diamesinae of the bloodworm family Chironomidae The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies wi ...

'' and ''

Potthastia ''Potthastia'' is a genus of non-biting midges in the subfamily Diamesinae of the bloodworm family Chironomidae The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a ...

'', and from ''

Cricotopus bicinctus ''Cricotopus bicinctus'' is a species of fly in the family Chironomidae. It is found in the Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of t ...

''. '' S. culicis'' has been found in '' Culex pipiens'' and the genera ''

Eukiefferiella ''Eukiefferiella'' is a genus of European non-biting midges in the subfamily Orthocladiinae of the bloodworm family (Chironomidae The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nemato ...

'' and '' Chironomus''. '' S. chinliense'' was found in a crane fly larva ('' Antocha'' sp.).Strongman, D. B. and S. Xu. (2006)
Trichomycetes from China and the description of three new ''Smittium'' species.
''Mycologia'' 98(3) 479–87. Host-specific ''Smittium'' include '' S. dimorphum'', which has only been observed in the midge ''

Boreoheptagyia lurida ''Boreoheptagyia'' is a genus of non-biting midges in the subfamily Diamesinae of the bloodworm family Chironomidae The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies ...

''. Some ''Smittium'' are useful in laboratory experiments. They are unusually easy to propagate in pure culture, and some 40% of the many ''Smittium'' species have been established as

axenic In biology, axenic (, ) describes the state of a culture in which only a single species, variety, or strain of organism is present and entirely free of all other contaminating organisms. The earliest axenic cultures were of bacteria or unicellul ...

isolates. Perhaps the best known species of the genus has been ''Smittium culisetae''. It is widespread and found in several host species, especially mosquitoes. It has been used often in laboratory research. Recent morphological and molecular studies indicated that it is different from ''Smittium'' species in the positioning of its zygospore, the shape of its trichospore (a type of

sporangium A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cy ...

), the

immune responses An immune response is a reaction which occurs within an organism for the purpose of defending against foreign invaders. These invaders include a wide variety of different microorganisms including viruses, bacteria, parasites, and fungi which could ...

Smittium mucronatum ''Smittium'' is a genus of fungus, fungi in the Order (biology), order Harpellales. It is the largest genus in the order. As of 2013, there were 81 described species.Wang, Y., et al. (2013)Overview of 75 years of ''Smittium'' research, establishi ...

'' *'' Smittium naiadis'' *'' Smittium nodifixum'' *'' Smittium orthocladii'' *'' Smittium ouselii'' *'' Smittium paludis'' *'' Smittium parvum'' *'' Smittium pennelli'' *'' Smittium perforatum'' *'' Smittium phytotelmatum'' *'' Smittium precipitiorum'' *'' Smittium prostratum'' *'' Smittium pseudodimorphum'' *'' Smittium pusillum'' *'' Smittium rarum'' *'' Smittium rupestre'' *'' Smittium shaanxiense'' *'' Smittium simulatum'' *'' Smittium simulii'' *'' Smittium tipulidarum'' *'' Smittium tronadorium'' *'' Smittium tynense'' *'' Smittium typhellum'' *'' Smittium urbanum''

References

{{Taxonbar, from=Q10672314 Zygomycota Zygomycota genera