Ophiocordyceps sinensis (formerly known as Cordyceps sinensis) or Yarsa-gumba, Yarsha-gumba or Yarcha-gumba, (in Nepali language) is an entomopathogenic fungus (a fungus that grows on insects) in the family Ophiocordycipitaceae. It mainly found in the meadows above 3,500 meters (11,483 feet) in the Himalayan regions of Nepal, Bhutan, India and Tibet. It parasitizes larvae of ghost moths and produces a fruiting body which used to be valued as a herbal remedy. However, the fruiting bodies harvested in nature usually contain high amounts of arsenic and other heavy metals so they are potentially toxic and sales have been strictly regulated by the CFDA (China Food and Drug Administration) in 2016.
O. sinensis parasitizes the larvae of moths within the family Hepialidae, specifically genera found on the Tibetan Plateau and in the Himalayas, between elevations of 3000 m and 5000 m. The fungus germinates in the living larva, kills and mummifies it, and then a dark brown stalk-like fruiting body which is a few centimeters long emerges from the corpse and stands upright.
It is known in English colloquially as caterpillar fungus, or by its more prominent names yartsa gunbu (Tibetan: , Wylie: dbyar rtswa dgun 'bu, literally "winter worm, summer grass"), or dōng chóng xià cǎo (Chinese: , literally "winter worm, summer grass").
O. sinensis is classified as a medicinal mushroom, and its use has a long history in traditional Chinese medicine as well as traditional Tibetan medicine. The hand-collected, intact fungus-caterpillar body is valued by herbalists as medicine, and because of its cost, its use is also a status symbol.
This fruiting bodies of the fungus are not yet cultivated commercially, but the mycelium form can be cultivated in vitro.Overharvesting and overexploitation have led to the classification of O. sinensis as an endangered species in China. Additional research needs to be carried out in order to understand its morphology and growth habits for conservation and optimum utilization.
Taxonomic history and systematics
Cordyceps sinensis consists of two parts, a fungal endosclerotium (within the caterpillar) and stroma. The stroma is the upper fungal part and is dark brown or black, but can be a yellow color when fresh, and longer than the caterpillar itself, usually 4–10 cm. It grows singly from the larval head, and is clavate, sublanceolate or fusiform, and distinct from the stipe (stalk). The stipe is slender, glabrous, and longitudinally furrowed or ridged.
The fertile part of the stroma is the head. The head is granular because of the ostioles of the embedded perithecia. The perithecia are ordinally arranged and ovoid. The asci are cylindrical or slightly tapering at both ends, and may be straight or curved, with a capitate and hemispheroid apex, and may be two to four spored. Similarly, ascospores are hyaline, filiform, multiseptate at a length of 5-12 μm and subattenuated on both sides. Perithecial, ascus and ascospore characters in the fruiting bodies are the key identification characteristics of O. sinensis.
Ophiocordyceps (Petch) Kobayasi species produce whole ascospores and do not separate into part spores. This is different from other Cordyceps species, which produce either immersed or superficial perithecia perpendicular to stromal surface, and the ascospores at maturity are disarticulated into part spores. Generally Cordyceps species possess brightly colored and fleshy stromata, but O. sinensis has dark pigments and tough to pliant stromata, a typical characteristic feature of most of the Ophiocordyceps species.
Developments in classification
The species was first described scientifically by Miles Berkeley in 1843 as Sphaeria sinensis;Pier Andrea Saccardo transferred the species to the genus Cordyceps in 1878. The fungus was known asCordyceps sinensis until 2007, when molecular analysis was used to emend the classification of the Cordycipitaceae and the Clavicipitaceae, resulting in the naming of a new family Ophiocordycipitaceae and the transfer of several Cordyceps species including C. sinensis to the genus Ophiocordyceps.
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