Cordyceps

''Cordyceps'' is a genus of ascomycete fungi (sac fungi) that includes over 260 species worldwide, many of which are parasitic. Diverse variants of cordyceps have had more than 1,500 years of use in Chinese medicine. Most ''Cordyceps'' species are endoparasitoids, parasitic mainly on insects and other arthropods (they are thus entomopathogenic fungi); a few are parasitic on other fungi.

The generic name ''Cordyceps'' is derived from the ancient Greek κορδύλη ''kordýlē'', meaning "club", and the Latin ''-ceps'', derived from Latin ''caput'', meaning "head". The genus has a worldwide distribution, with most of the known species being from Asia.

Taxonomy

There are two recognized subgenera:
*''Cordyceps'' subgen. ''Cordyceps'' Fr. 1818
*''Cordyceps'' subgen. ''Cordylia'' Tul. & C. Tul. 1865

''Cordyceps'' sensu stricto are the teleomorphs of several genera of anamorphic, entomopathogenic fungi such as '' Beauveria'' ('' Cordyceps bassiana''), '' Septofusidium'', and '' Lecanicillium''.

Splits

''Cordyceps'' subgen. ''Epichloe'' was at one time a subgenus, but is now regarded as a separate genus, '' Epichloë''.

''Cordyceps'' subgen. ''Ophiocordyceps'' was at one time a subgenus defined by morphology. Nuclear DNA sampling done in 2007 shows that members, including " C. sinensis" and " C. unilateralis", as well as some others not placed in the subgenus, were distantly related to most of the remainder of species then placed in ''Cordyceps'' (e.g. the type species ''C. militaris''). As a result, it became its own genus, absorbing new members.

The 2007 study also peeled off '' Metacordyceps'' (anamorph '' Metarhizium'', '' Pochonia'') and '' Elaphocordyceps''. A number of species remain unclearly assigned and provisionally retained in ''Cordyceps'' sensu lato.

Selected species

There are over 260 species in the genus ''Cordyceps'' including the following species:

*'' Cordyceps caespitosa''
*'' Cordyceps chanhua''
*'' Cordyceps militaris''
*'' Cordyceps sinclairii''

Anamorphic genera

''Isaria'' is a genus name that has been applied to many anamorphs of ''Cordyceps'' species. This genus itself is treated as a synonym of ''Cordyceps'' in Species Fungorum following the "one fungus one name" change, but many species names with ''Isaria'' are still preferred by Species Fungorum over the synonyms in other genera (e.g. ''Isaria sinclarii'' is preferred over ''Cordyceps sinclairii''). Though confusing, this does match the "equal footing for priority" approach of the "one fungus one name" concept. To add to the complexity, ''Isaria'' is a conserved name with a conserved type. What remains under ''Isaria'' as of 2016 remains polyphyletic and can be divided into three main clades.

Other important anamorphic genera closely allied to ''Cordyceps'' sensu stricto include '' Evlachovaea'', '' Lecanicillium'' and '' Beauveria''. Dai ''et al.'' (2016) concludes their article on the phylogeny of ''Isaria'' with the following commentary on future nomenclature under "one fungus one name" (original in Chinese):

Biology

When ''Cordyceps'' attacks a host, the mycelium invades and eventually replaces the host tissue, while the elongated fruit body ( ascocarp) may be cylindrical, branched, or of complex shape. The ascocarp bears many small, flask-shaped perithecia containing asci. These, in turn, contain thread-like ascospores, which usually break into fragments and are presumably infective.

Research

Polysaccharide components and the nucleoside cordycepin isolated from '' C. militaris'' are under basic research, but more advanced clinical research has been limited and too low in quality to identify any therapeutic potential of cordyceps components.

Uses

''Cordyceps'' sensu lato (which now includes '' Ophiocordyceps'' and many other genera holding species originally in this genus) has long been used in traditional Chinese medicine in the belief it can be used to treat diseases. There is no strong scientific evidence for such uses.

Cultural representations

The video game series '' The Last of Us'' (2013–present) and its television adaptation present ''Cordyceps'' as a deadly threat to the human race, its parasitism powerful enough to result in global calamity. The result is a zombie apocalypse and the collapse of human civilization. ''Scientific American'' notes that some species in the genus "are indeed body snatchers–they have been making real zombies for millions of years", though of ants or tarantulas, not of humans. ''The Last of Us'' proceeds from the premise that a new species of ''Cordyceps'' manages to jump the species barrier, from nonhuman to human, as diseases like influenza and viruses like Ebola and COVID-19 have done. Its human hosts initially become violent "infected" beings, before turning into blind zombie "clickers", complete with fungal "fruiting bodies sprouting from their faces". In an additional detail that reflects ''Cordyceps'' biology, "clickers" then seek out a dark place in which to die and release the fungal spores, enabling the parasite to complete its life cycle. ''Scientific American'' comments that by combining a plausible mechanism with effective artistic design, the series gains "both scientific rigor and beauty".

In similar vein, ''Cordyceps'' causes a pandemic that wipes out most of humanity in Mike Carey's 2014 postapocalyptic novel '' The Girl with All the Gifts'' and its 2016 film adaptation. In this case, an infected person becomes a "hungry", a zombie thirsting for blood. In the fiction, Dr. Caldwell explains that the human-infecting fungus is a mutated form of ''Ophiocordyceps unilateralis'' (a group of species now split off from ''Cordyceps'') which alters the behaviour of infected insects. The children of infected mothers, however, become "hybrids" with antibodies protecting them against the fungus.

Gallery

File:Cordycepsmilitaris.jpg, ''Cordyceps militaris''
File:Puppenkernkeule.jpg, ''Cordyceps militaris''
File:Cordyceps ophioglossoides 02.JPG, '' Cordyceps ophioglossoides''

See also

* Medicinal fungi

References

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Cordyceps
Edible fungi
Parasitic fungi
Sordariomycetes genera
Taxa named by Elias Magnus Fries
Taxa described in 1818