Last chance to know? Using literature to explore the biogeographyand invasion biology of the death cap mushroom Amanita phalloides(Vaill. ex Fr. :Fr.) LinkAnne Pringle1,* & Else C. Vellinga21Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA;2Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA,94720-3102, USA; *Author for correspondence (e-mail: [email protected]; fax: +1-617-495-9300)Received 29 April 2005; accepted in revised form 6 October 2005Key words: exotic or invasive mushroom or fungi, fungal biogeography, invasion and mutualism, invasivespecies, microbial invasion, species concepts, symbiosisAbstractThe biogeography of fungi is poorly understood and a species in a novel locat ion may be an introduction oran endemic newly identified within its native range. Using the literature of Amanita phalloides as a casestudy, we aim to illustrate both the limit ed utility of the historical record in establishing ectomycorrhizal(EM) species as introduced or invasive, and the difficulty of using modern records to establish a currentbiogeography. Amanita phalloides, the death cap mushroom, is deadly. It is a notorious fungus with a richliterature. His torical records can be used to explore the species’ distribution in North America, where theearliest publication on A. phalloides dates to 1834, and four different authors identified it as growing inCalifornia, Minnesota, Pennsylvania, North Carolina, and Maryland be fore 1910. In contrast, by mid-century field guides listed A. phalloides as rare on the West Coast and absent from the East Coast. Inmodern literature A. phalloides is described as a recently introduced and currently invasive species. Thecontradictions raise two questions: First, is A. phalloides an exotic to North America, and second, can earlyrecords be used to delineate the native distribution of any other less infamous EM fungus? We argue thatconfusion on the introduced status and biogeography of A. phalloides, and perhaps other fungi, is the directresult of shifting species concepts. When publications include an explicit species concept they can be used toestablish A. phalloides as an introduction, for example on the East Coast of North America and inAustralia. When species concepts are vague the literature is not useful and cannot be used to determineA. phalloides as an introduction, for example on the West Coast of North America or in Asia.Abbreviation: EM – ectomycorrhizalIntroductionResearch on the invasion biology of fungi hasfocused primarily on plant pathogenic fungi.Infamous examples of introduced and invasiveplant pathogens include chestnut blight (Crypho-nectria parasitica), Dutch elm disease (Ophios-toma ulmi), and white pine blister rust(Cronartium ribicola). Rather less is known aboutthe introduction or invasion of nonpathogenicfungi. Careful work has been done with a fewspecies, for example the saprobe Clathrus archeri(Parent and Thoen 1986; Parent et al. 2000) andthe ectomycorrhizal fungus Amanita muscariaBiological Invasions (2006) 00:1–14 Ó Springer 2006DOI 10.1007/s10530-005-3804-2(Sawyer et al. 2001; Bagley and Orl ovich 2004).Fungi associated with plants have been movedwhen trees are planted for agriculture (Garrido1986; Dunstan et al. 1998) and edible mush-rooms, especially truffles, have been cultivated onplantations outside their native range (Sogg 2000;Yun and Hall 2004). Scant attention is paid tothe ecological consequences of transporting non-pathogenic fungi across continents (but see Ville-neuve et al. 1991; Chapela et al. 2001; Diez2005). Monitoring efforts aimed at tracking thedispersal of introduced fungi to native forestsare rare in America, but more common inEurope and Australia (for example, the Austra-lian fungimap.rbg.vic.gov.au).Ectomycorrhizal (EM) fungi function as obli-gate symbionts of plants (Frank 1885, Trappe2005). The association is often assumed to be amutualism but may range across a continuum ofparasitism to mutualism (Egger and Hibbett2004; Jones and Smith 2004). In nature ectomy-corrhizal (EM) fungi form species-rich communi-ties in which an individual fungus may colonizemultiple trees (Horton and Bruns 1998; Kennedyet al. 2003), and an individual tree may associatewith multiple fungi (Bruns 1995).A notorious species of EM fungus is Amanitaphalloides, or the death cap or death cup mush-room. It is fatally poisonous and according tofolklore an A. phalloides mushroom was used byAgrippina to kill the Emporer Claudius so thather son Nero might be Caesar (Benjamin 1995).More recent ly A. phalloides has killed a spate ofindividuals in California (Rattanvilay et al. 1982;Freedman 1996a, b; Zevin et al. 1997; Hoffman2004). Because A. phalloides is deadly it attractsa great deal of attention and a rich literaturerecords A. phalloides’ distribution in NorthAmerica.At this time the mushroom is abundant inboth the urban landscapes and undisturbed for-ests of California (personal observations), but theliterature conflicts on whether or not A. phallo-ides is native. Amanita phalloides was recorded inCalifornia as early as 1880 (Harkness and Moore1880). In later publications A. phalloides isdescribed as a newly introduced and invasivespecies (e.g. Saylor 1984a, b). Is A. phalloidesnative, as the 1880 record would suggest, orintroduced? California is a biodiversity hotspot(Stein et al. 2000) and if A. phalloides is an exoticspecies it would be invading into a complex fun-gal community. A similar story can be told forA. phalloides on the East Coast; early reports(Schweinitz 1834; Taylor 1897; McIlvaine andMacAdam 1902) give way to later descriptions ofA. phalloides as introduced and invasive (Tanghe1983).As humans continue to facilitate species’migrations across continents the biogeography oforganisms is shifting. Mycorrhizal fungi are noexception and yet examples of invasive EM taxaare rare. How can early records be used to delin-eate the native distribution of A. phalloides andother (and especially less charismatic) EM fungi?By using the literature of A. phalloides as a casestudy we aim to illustrate both the utility of thehistorical record in establishing EM species asintroduced or invasive and the difficulty ofdescribing the past and present biogeography ofmushrooms.Materials and methodsBy focusing on the historical literature ofA. phalloides in North America, and modernliterature of A. phalloides across the globe,