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''Amanita exitialis'', also known as the Guangzhou destroying angel, is a mushroom of the large genus ''Amanita''. It is distributed in eastern Asia, and probably also in India where it has been misidentified as ''A. verna''. Deadly poisonous, it is a member of section Phalloideae and related to the death cap ''A. phalloides''. The fruit bodies (mushrooms) are white, small to medium-sized with caps up to in diameter, a somewhat friable ring and a firm volva. Unlike most agaric mushrooms which typically have four-spored basidia (spore-bearing cells), the basidia of ''A. exitialis'' are almost entirely two-spored. Eight people were fatally poisoned in China after consuming the mushroom in 2000, and another 20 have been fatally poisoned since that incident. Molecular analysis shows that the species has a close phylogenetic relationship with three other toxic white Amanitas: ''A. subjunquillea'' var. ''alba'', ''A. virosa'' and ''A. bisporigera''. ==Taxonomy, classification, and phylogeny== Zhu-Liang Yang and Tai-Hui Li discovered the species by reexamining various herbarium specimens of white ''Amanita'' typically referred to as either ''A. verna'' or ''A. virosa''. They realized that collections referred to as these European species actually comprised three taxa new to science or the region.〔The other two ''Amanita'' taxa identified in the publication were ''Amanita oberwinklerana'', new to China, and ''Amanita subjunquillea'' var. ''alba'', which had its known Chinese range greatly extended.〕 The holotype specimen of ''A. exitialis'' is located in the Mycological Herbarium of Guangdong Institute of Microbiology.〔 |2=''A. bisporigera'' }} |2=''A. fuliginea'' }} |2=''A. hemibapha'' }} }} }} | caption=Phylogeny and relationships of ''Amanita exitialis'' and related species based on ITS sequence data. The ''A. virosa'' specimen was collected from Japan, ''A. bisporigera'' was from the USA, and the other species from China.〔 }} In 2005, Zhang and colleagues performed a phylogenetic analysis based on the ITS sequences of several white-bodied toxic ''Amanita'' species. Their results support a clade containing four lethal ''Amanita'' species with white fruit bodies. ''A. exitialis'' has two-spored basidia similar to the North American species ''A. bisporigera'', but ''A. exitialis'' has a closer phylogenetic relationship with ''Amanita subjunquillea'' var. ''alba'', a four-spored white lethal species from China.〔 The specific epithet ''exitialis'' derives from the Latin word "destructive", and refers to the lethally poisonous nature of the mushroom.〔 ''Amanita exitialis'' is classified in the section Phalloideae of the genus ''Amanita''. Species of this section share the following characteristics: spores that are not strongly elongated, and never with a cyclindric shape; flesh not reddening upon bruising; lamellulae (short gills that do not reach the edge of the cap) abruptly cut off; a well-formed pouch- or sac-like membranous volva. All species of Phalloideae are ectomycorrhizal and contain amatoxins.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Amanita exitialis」の詳細全文を読む スポンサード リンク
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