# Smittium

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***Smittium*** is a [genus](/source/Genus) of [fungi](/source/Fungus) in the [order](/source/Order_(biology)) [Harpellales](/source/Harpellales). It is the largest genus in the order. As of 2013, there were 81 described species.[1] Many of these have been formally described only recently; in 1998 there were just 46.[2] Several have been transferred to *Smittium* from other genera, such as *[Orphella](/source/Orphella)*, *[Rubetella](/source/Rubetella)*, *[Genistella](/source/Genistella)*, and *[Typhella](/source/Typhella)*.[3] In general, the genus has a [cosmopolitan distribution](/source/Cosmopolitan_distribution), but some species are limited to small regions.[1]

Like most other fungi of the Harpellales, these are found in the guts of [insect](/source/Insect) [larvae](/source/Larva). *Smittium* are most often resident in the larvae of [aquatic](/source/Aquatic_insects) [flies](/source/Fly). The genus was named for *[Smittia](/source/Smittia)*, the [midge](/source/Midge) from which it was first isolated. The fungi can be found in [black flies](/source/Black_fly), [mosquitoes](/source/Culicidae), [solitary midges](/source/Thaumaleidae), and [non-biting](/source/Chironomidae) and [biting midges](/source/Ceratopogonidae). The relationship between the fungus and the fly is usually [commensal](/source/Commensalism).[1] Sometimes it is more [mutualistic](/source/Mutualism_(biology)), such as when the fungus synthesizes [vitamins](/source/Vitamin) or other nutrients for the host.[4] One species, though, *[Smittium morbosum](/source/Smittium_morbosum)*, can best be described as [parasitic](/source/Parasitism) on its mosquito larva host, killing it by preventing it from [molting](/source/Moulting). No other gut fungi are known to be lethal to their hosts in this way.[1]

The host larva is infected with *Smittium* when it ingests the fungal [spore](/source/Spore).[5] *Smittium* generally live in the [hindgut](/source/Hindgut) of the fly larva, attaching to the [chitinous](/source/Chitin) gut lining[1] via a [hypha](/source/Hypha). When the fungus produces spores, they are excreted by the host.[5]

Sometimes several species can be found in the gut flora of one host. *[S. brevisporum](/source/Smittium_brevisporum)*, *[S. bulbosporophorus](/source/Smittium_bulbosporophorus)*, and *[S. inexpectans](/source/Smittium_inexpectans)* have been noted growing together, for example.[3] Other genera of gut fungi can be present, as well, such as *[Genistellospora](/source/Genistellospora)*.[6] Some *Smittium* can be found in a number of hosts, while others are more host-specific. *[S. heterosporum](/source/Smittium_heterosporum)* has been collected from nonbiting midges of the genera *[Sympotthastia](/source/Sympotthastia)* and *[Potthastia](/source/Potthastia)*, and from *[Cricotopus bicinctus](/source/Cricotopus_bicinctus)*. *[S. culicis](/source/Smittium_culicis)* has been found in *[Culex pipiens](/source/Culex_pipiens)* and the genera *[Eukiefferiella](/source/Eukiefferiella)* and *[Chironomus](/source/Chironomus)*.[3] *[S. chinliense](/source/Smittium_chinliense)* was found in a [crane fly](/source/Crane_fly) larva (*[Antocha](/source/Antocha)* sp.).[7] Host-specific *Smittium* include *[S. dimorphum](/source/Smittium_dimorphum)*, which has only been observed in the midge *[Boreoheptagyia lurida](/source/Boreoheptagyia_lurida)*.[6]

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](/source/Axenic) [isolates](/source/Cell_culture).[1]

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](/source/Morphology_(biology)) and molecular studies indicated that it is different from *Smittium* species in the positioning of its [zygospore](/source/Zygospore), the shape of its trichospore (a type of [sporangium](/source/Sporangium)), the [immune responses](/source/Immune_system) it induces in hosts, its [isozymes](/source/Isozyme), and other molecular characteristics. The fungus was renamed *Zancudomyces culisetae* and placed in a [monotypic genus](/source/Monotypic_genus) of its own, *[Zancudomyces](/source/Zancudomyces)*.[1]

Species include:[8]

- *[Smittium aciculare](/source/Smittium_aciculare)*
- *[Smittium acutum](/source/Smittium_acutum)*[2]
- *[Smittium alpinum](/source/Smittium_alpinum)*
- *[Smittium angustum](/source/Smittium_angustum)*
- *[Smittium annulatum](/source/Smittium_annulatum)*[9]
- *[Smittium arcticum](/source/Smittium_arcticum)*
- *[Smittium arvernense](/source/Smittium_arvernense)*
- *[Smittium basiramosum](/source/Smittium_basiramosum)*
- *[Smittium biforme](/source/Smittium_biforme)*
- *[Smittium bisporum](/source/Smittium_bisporum)*
- *[Smittium brasiliense](/source/Smittium_brasiliense)*
- *[Smittium brevisporum](/source/Smittium_brevisporum)*[3]
- *[Smittium bulbosporophorum](/source/Smittium_bulbosporophorum)*[3]
- *[Smittium bullatum](/source/Smittium_bullatum)*
- *[Smittium caribense](/source/Smittium_caribense)*
- *[Smittium caudatum](/source/Smittium_caudatum)*[2]
- *[Smittium cellaspora](/source/Smittium_cellaspora)*
- *[Smittium chinliense](/source/Smittium_chinliense)*[7]
- *[Smittium chironomi](/source/Smittium_chironomi)*
- *[Smittium coloradense](/source/Smittium_coloradense)*
- *[Smittium commune](/source/Smittium_commune)*[2]
- *[Smittium compactum](/source/Smittium_compactum)*
- *[Smittium culicis](/source/Smittium_culicis)*
- *[Smittium culicisoides](/source/Smittium_culicisoides)*[9]
- *[Smittium cylindrosporum](/source/Smittium_cylindrosporum)*
- *[Smittium delicatum](/source/Smittium_delicatum)*
- *[Smittium dimorphum](/source/Smittium_dimorphum)*
- *[Smittium dipterorum](/source/Smittium_dipterorum)*[9]
- *[Smittium ditrichosporum](/source/Smittium_ditrichosporum)*[10]
- *[Smittium elongatum](/source/Smittium_elongatum)*
- *[Smittium esteparum](/source/Smittium_esteparum)*
- *[Smittium fasciculatum](/source/Smittium_fasciculatum)*
- *[Smittium fastigatum](/source/Smittium_fastigatum)*
- *[Smittium fecundum](/source/Smittium_fecundum)*
- *[Smittium fruticosum](/source/Smittium_fruticosum)*
- *[Smittium gigasporum](/source/Smittium_gigasporum)*
- *[Smittium gracilis](/source/Smittium_gracilis)*[3]
- *[Smittium gravimetallum](/source/Smittium_gravimetallum)*
- *[Smittium hecatei](/source/Smittium_hecatei)*[3]
- *[Smittium heterosporum](/source/Smittium_heterosporum)*[3]
- *[Smittium imitatum](/source/Smittium_imitatum)*
- *[Smittium incrassatum](/source/Smittium_incrassatum)*
- *[Smittium inexpectans](/source/Smittium_inexpectans)*[3]
- *[Smittium insulare](/source/Smittium_insulare)*[10]
- *[Smittium kansense](/source/Smittium_kansense)*[2]
- *[Smittium lentaquaticum](/source/Smittium_lentaquaticum)*
- *[Smittium longisporum](/source/Smittium_longisporum)*
- *[Smittium macrosporum](/source/Smittium_macrosporum)*
- *[Smittium magnosporum](/source/Smittium_magnosporum)*
- *[Smittium megazygosporum](/source/Smittium_megazygosporum)*
- *[Smittium microsporum](/source/Smittium_microsporum)*
- *[Smittium minutisporum](/source/Smittium_minutisporum)*
- *[Smittium morbosum](/source/Smittium_morbosum)*
- *[Smittium mucronatum](/source/Smittium_mucronatum)*
- *[Smittium naiadis](/source/Smittium_naiadis)*[7]
- *[Smittium nodifixum](/source/Smittium_nodifixum)*[7]
- *[Smittium orthocladii](/source/Smittium_orthocladii)*
- *[Smittium ouselii](/source/Smittium_ouselii)*
- *[Smittium paludis](/source/Smittium_paludis)*
- *[Smittium parvum](/source/Smittium_parvum)*[9]
- *[Smittium pennelli](/source/Smittium_pennelli)*
- *[Smittium perforatum](/source/Smittium_perforatum)*
- *[Smittium phytotelmatum](/source/Smittium_phytotelmatum)*
- *[Smittium precipitiorum](/source/Smittium_precipitiorum)*
- *[Smittium prostratum](/source/Smittium_prostratum)*[3]
- *[Smittium pseudodimorphum](/source/Smittium_pseudodimorphum)*[3]
- *[Smittium pusillum](/source/Smittium_pusillum)*
- *[Smittium rarum](/source/Smittium_rarum)*
- *[Smittium rupestre](/source/Smittium_rupestre)*
- *[Smittium shaanxiense](/source/Smittium_shaanxiense)*
- *[Smittium simulatum](/source/Smittium_simulatum)*
- *[Smittium simulii](/source/Smittium_simulii)*
- *[Smittium tipulidarum](/source/Smittium_tipulidarum)*
- *[Smittium tronadorium](/source/Smittium_tronadorium)*
- *[Smittium tynense](/source/Smittium_tynense)*[10]
- *[Smittium typhellum](/source/Smittium_typhellum)*
- *[Smittium urbanum](/source/Smittium_urbanum)*

## References

1. 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.](https://www.academia.edu/2018953/Overview_of_75_years_Smittium_research_establishing_a_new_genus_for_Smittium_culisetae_and_prospects_for_future_revisions_of_the_Smittium_clade) *Mycologia* 105(1) 90-111.

1. Lichtwardt, R. W. and R. D. Grigg. (1998). [Four new *Smittium* species inhabiting the hindgut of Chironomidae larvae.](https://www.jstor.org/discover/10.2307/3761402?uid=3739560&uid=2&uid=4&uid=3739256&sid=21102352272067) *Mycologia* 90(3) 427-33.

1. Valle, L. G. and S. Santamaria. (2004). [The genus *Smittium* (Trichomycetes, Harpellales) in the Iberian Peninsula.](http://www.mycologia.org/content/96/3/682.full) *Mycologia* 96(3) 682-701.

1. 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.

1. Vojvodic, S. and J. W. McCreadie. (2008). [Do different species of *Smittium* (Harpellales, Legeriomycetaceae) influence each other in the host gut?](http://www1.bio.ku.dk/forskning/oe/cse/media/vojvodic.and.mccreadie.2008.mycolres.pdf/)[dead link] *Mycological Research* 112 1409-13.

1. 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.](http://www.bioline.org.br/request?oc02082) *Memórias do Instituto Oswaldo Cruz* 97(3) 423-26.

1. Strongman, D. B. and S. Xu. (2006). [Trichomycetes from China and the description of three new *Smittium* species.](http://www.ephemeroptera-galactica.com/pubs/pub_s/pubstrongmand2006p479.pdf) *Mycologia* 98(3) 479–87.

1. [*Smittium*.](http://www.speciesfungorum.org/Names/names.asp?strGenus=Smittium) Species Fungorum. CABI. 2013.

1. Lichtwardt, R. W. (1997). [Costa Rican gut fungi (Trichomycetes) infecting lotic insect larvae.](http://www.biologiatropical.ucr.ac.cr/attachments/volumes/vol45-4/05_Lichtwardt_Gut_fungi.pdf) *Rev Biol Trop* 45(4) 1349-83.

1. Strongman, D. B. (2007). [Trichomycetes in aquatic insects from Prince Edward Island, Canada.](http://www.ingentaconnect.com/content/nrc/cjb/2007/00000085/00000010/art00007) *Canadian Journal of Botany* 85(10) 949-63.

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Adapted from the Wikipedia article [Smittium](https://en.wikipedia.org/wiki/Smittium) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Smittium?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.