advances in glomeromycota taxonomy and classification

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v o l u m e 2 · n o . 2 191

© 2011 International Mycological Association

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Advances in Glomeromycota taxonomy and classification

Fritz Oehl1, Ewald Sieverding2, Javier Palenzuela3, Kurt Ineichen4, and Gladstone Alves da Silva5

1AgroscopeReckenholz-TänikonResearchStation(ART),EcologicalFarmingSystems,Reckenholzstrasse191,CH-8046Zürich,Switzerland;correspondingauthore-mail:fritz.oehl@art.admin.ch2InstituteofPlantProductionandAgroecologyintheTropicsandSubtropics,UniversityofHohenheim,Garbenstrasse13,D-70593Stuttgart,Germany3Departamento deMicrobiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, ProfesorAlbareda 1, 18008Granada, Spain4Basel-ZürichPlantScienceCenter,InstituteofBotany,UniversityofBasel,Hebelstrasse1,CH-4056Basel,Switzerland5Departamento deMicologia, CCB,Universidade Federal dePernambuco,Av. Prof. NelsonChaves s/n, CidadeUniversitaria, 50670-420,Recife, PE, Brazil

Abstract: Concomitantmorphologicalandmolecularanalyseshaveledtomajorbreakthroughsinthetaxonomicorganization of the phylum Glomeromycota.Fungiinthisphylumareknowntoformarbuscularmycorrhiza,andsofarthreeclasses,fiveorders,14familiesand29generahavebeendescribed.Sensu lato,sporeformationin10ofthearbuscularmycorrhiza-forminggeneraisexclusivelyglomoid,oneisgigasporoid,sevenarescutellosporoid,fourareentrophosporoid, twoareacaulosporoid,andoneispacisporoid.Sporebimorphismisfoundinthreegenera,andonegenusisassociatedwithcyanobacteria.Herewepresentthecurrentclassificationdevelopedinseveralrecentpublicationsandprovideasummarytofacilitatetheidentificationoftaxafromgenustoclasslevel.

Article info:Submitted10November2011;Accepted:16November2011;Published:18November2011.

Key words: ArchaeosporomycetesendomycorrhizasevolutionGigasporalesGlomeralesGlomeromycetesParaglomeromycetesphylogenyVA mycorrhiza

doi:10.5598/imafungus.2011.02.02.10 IMA FuNgus · voluMe 2 · No 2: 191–199

INtroductIoN

Glomeromycotataxonomywaslargelymorphologicallydrivenup to the end of the lastmillennium.All glomeromycoteanfungi, except one genus, are known to form arbuscularmycorrhiza. Their identification was based on sporemorphology, spore formation, and spore wall structure (e.g.Gerdemann&Trappe1974,Walker&Sanders1986,Morton & Benny 1990, Schenck & Pérez 1990). However,as soon as molecular phylogenetic tools became available, theywereincludedintaxonomicanalyses(e.g.Simonet al.1992) and soon became the drivers of the establishmentofanewtaxonomy(Morton&Redecker2001,Schüßler et al.2001).In1990,withoutthebenefitofmolecularaspects,the arbuscular mycorrhiza-forming fungi were organized in three families (Acaulosporaceae, Gigasporaceae, and Glomeraceae)andsixgenera(Acaulospora, Entrophospora, Gigaspora, Glomus, Sclerocystis, and Scutellospora)within one order, Glomerales (Morton&Benny1990)ofthefungal phylum Zygomycota. That classification was basedon spore morphology and spore formation characteristics (acaulosporoid, entrophosporoid, gigasporoid, glomoid,

radial-glomoid, and scutellosporoid). Differences in sporewallstructurewereusedatthespecieslevel.

Today, we accept three classes (Archaeosporomycetes, Glomeromycetes, and Paraglomeromycetes), five orders(Archaeosporales, Diversisporales, Gigasporales, Glomerales and Paraglomerales),14families,29generaandapproximately230 species (e.g.Morton&Redecker2001,Schüßler et al.2001, Oehl & Sieverding 2004, Walker & Schüßler 2004,Sieverding&Oehl2006,Spainet al.2006,Oehlet al.2008,2011a–d,Palenzuelaet al.2008).

Until recently, it was unclear whether glomoid and gigasporoid species could be further divided into different morphologicalgroupscongruentwiththemajorphylogeneticcladesobtainedbymolecularanalyses.Afirstrevisionofthesporogenouscell forming (gigasporoidandscutellosporoid)Glomeromycetes according to concomitant morphological andphylogeneticfeatures(Oehletal.2008)wasnotacceptedbyallmycologists (Morton&Msiska2010).However, laterstudieswithabroaderdatabase(e.g.Gotoet al.2010,2011,Oehl et al. 2010, 2011b) confirmed that the revised genusScutellospora, as well as the new Racocetra, Cetraspora, Dentiscutata, and Orbispora,aremonophyletic.

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192 i m a f u n G u S

A large group of species forms glomoid spores, and it had been believed that there were too few morphological charactersofsignificancetodifferentiatethem.Taxonomistshave consequently started basing groupings of the glomoid species almost exclusively on molecular phylogeneticcharacters. A recent revision of these glomoid specieshas, however, shown that molecular phylogeny is actually congruent with the morphological characteristics of these fungi(Oehlet al.2011c).Fungalspecieswithentrophosporoidspore formation were also revised (Oehl et al. 2011d).Theobjectiveof thispaper is topresent thecurrentoverallclassification system ofGlomeromycota that has emerged from these recent studies, and to summarize the majormorphologicalfeaturesinthephylumdowntogenuslevel.

MAterIAls ANd Methods

The morphological, molecular, and phylogenetic analyses performed are presented in a series of recent publications dealing with different species groups of Glomeromycota(e.g.Oehl et al. 2006, 2010, 2011a, b, d, f, Sieverding & Oehl2006,Silvaet al.2006,Spainet al.2006,Palenzuelaet al. 2008,2010,2011).

results ANd dIscussIoN

Figure 1 is a schematic tree for Glomeromycota based on molecular phylogenetic analyses of the SSU, ITS region, partial LSUoftherRNAgene,andpartialβ-tubulingene(e.g.Oehlet al.2008,2010,2011a–d).InTable1,themajormorphologicalfeaturesofallhigher level taxaarepresented,with the taxaarranged according to their taxonomic rank down to genus.Threeglomeromycoteanclasses,fiveorders,14families,and29generahavebeenrecognizedtodate(Table1).Sensu lato, spore formation in 10 of the arbuscular mycorrhiza-forminggenerahaveexclusivelyglomoid,onehasgigasporoid,sevenhave scutellosporoid, four have entrophosporoid, two genera have acaulosporoid, and one has pacisporoid spore formation, while three genera show spore bimorphism, and one genus is associated with cyanobacteria (the only one not formingarbuscularmycorrhizas).

Hitherto, Paraglomeromycetes are monogeneric (Table1), are characterized by mono-walled spores formedterminally on hyphae (i.e. glomoid sporessensu lato), andgerminate directly through the sporewall.Their arbuscularmycorrhizal structures do not or only faintly stain in trypan blue. Archaeosporomycetes includes organisms that are exclusivelybimorphicsincetheyformeitheracaulosporoidorentrophosporoid spores simultaneously with glomoid spores, or are associated with cyanobacteria. The mycorrhizalstructures of Archaeosporaceae are similar to those of Paraglomeraceae, while Ambisporaceae form vesicular-arbuscular mycorrhizal structures staining pale blue in trypan blue.Incontrast,mycorrhizalstructuresinGlomeromycetes

stainblue todarkblue in trypanblue. InGlomeromycetes, Gigasporales species do not form intraradical vesicles but auxiliary cells in soils, which clearly distinguish them fromGlomerales and Diversisporales.

Gigasporalesexhibitgigasporoidorscutellosporoidsporeformation (Oehlet al.2011b), i.e. spores formed terminallyon sporogenous cells and with either germ warts on the inner surface of the mono-walled spore wall (gigasporoid;Gigasporaceae), or a discrete germination shield on theinnermost (= ‘germinalwall’)of2–4walls (scutellosporoid).There are three families with scutellosporoid spore formation (sensu lato): Dentiscutataceae, Racocetraceae and Scutellosporaceae(Oehlet al.2008).Scutellosporaceae form mono-lobed(Orbispora)orbi-lobed(Scutellospora),hyalinegerminationshields(Figs2–4).Racocetraceae species form wavy-like, multiply lobed, hyaline germination shields and haveeithertwo(Racocetra)orthree(Cetraspora)sporewalls(Figs5–8).Dentiscutataceae species form yellow-brown to browngermshields thatarebi-lobed (Fuscutata;Fig.9)orwith multiple compartments (Dentiscutata, triple-walled;Quatunicafour-walled;Figs10–11).

In Archaeosporales and Diversisporales, four genera have spore formation laterally on the neck of terminal or intercalary sporiferous saccules (= acaulosporoid sensu lato; Table 1): Acaulospora, Otospora, and the bi-morphic Ambispora and Archaeospora.Thesegeneracaneasilybeseparated on spore wall number and spore wall structure (Palenzuela et al. 2008). Triple-walled Acaulospora species have a characteristic granular, ‘beaded’ inner wallsurface(Morton&Benny1990),which isabsent inacaulo-ambisporoid spores of triple-walled Ambispora species (Spainet al.2006,Palenzuelaet al.2011).Thewallstructureof the bi-walled Otospora ismore complex than that of bi-walled Archaeosporaspecies(Palenzuelaet al.2008).

In Archaeosporales, Diversisporales, and Glomerales, there are five genera with spore formation within theneck of terminal or intercalary sporiferous saccules (i.e.entrophosporoid sensu lato; Table 1): Entrophospora, Kuklospora, Sacculospora, Tricispora, and bimorphic Intraspora (Oehlet al.2011d).Triple-walledKuklospora has the characteristic granular, ‘beaded’ inner wall surface ofAcaulosporaceae(Sieverding&Oehl2006),whichisabsentin spores of triple-walled Sacculospora (Oehlet al.2011d).The wall structure of bi-walled Entrophospora and Tricispora ismorecomplexthanthatofbi-walled,bimorphicIntraspora species (Sieverding & Oehl 2006, Oehl et al. 2011d).Entrophospora and Tricispora can be distinguished through the twocicatrices (scars)andporestructuresproximalanddistal to thesporiferoussaccule: theproximalpore iswidein Tricispora and closed by a septum, while it is narrow and closed by a plug in Entrophospora.Thedistalporeandscaris absent in Entrophospora from the structural layer, and formed only on the overlying, hyaline, evanescent layer, while, in light microscopy, the distal pore with a distal scar is obvious in Tricispora (Sieverding&Oehl2006,Palenzuelaet al.2010,Oehlet al.2011d).

Advances in Glomeromycota classificationARTIC

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193v o l u m e 2 · n o . 2

Fig. 1. Representative tree of the phylum Glomeromycotabasedonmolecular(SSU,ITSregion,partialLSUof therRNAgene,andpartialβ-tubulinegene)andmorphologicalanalyses(sporewallstructures,structuresofthesporebasesandsubtendinghyphae,germination,andgerminationshieldstructures).Adaptedfrom(Oehlet al. 2008,2011a–d).Thedrawingsinthecentralcolumnsshowthesporeformationtypesofthegenera,andthetypicalgerminationshieldsforthosegenerawhichformpersistentshieldsalreadyduringsporeformation.

oehl et al.ARTICLE


tabl

e 1.MajormorphologicalcharactersforhigherleveltaxaofG

lom

erom

ycot

afromclasstogenuslevel.

cla

ssO

rder

Fam

ilyG

enus

Spo

re fo

rmat

ion

Num

berof

spor

e w

alls

Germination;specific

germ

inat

ion

stru

ctur

e Mycorrhizalstructures;

stai

ning

in T

rypa

n bl

ue

Glo

mer

omyc

etes

Germtube(gt)

Vesi

cles

, Arb

uscl

es,

Hyphae

Glo

mer

ales

Glo

mer

acea

eG

lom

us

Glomoid(terminallyonhyphae)

1

gt th

roug

h hy

pha

V,A,H

Funn

elifo

rmis

Glo

moi

dFu

nnel

iform

oid

sens

u st

ricto

1

gt th

roug

h hy

pha

V,A,H

Sep

togl

omus

Glo

moi

dS

epto

glom

oid

sens

u st

ricto

1

gt th

roug

h hy

phae

V,A,H

Sim

iglo

mus

Glo

moi

dS

imig

lom

oid

sens

u st

ricto

1

gt th

roug

h hy

pha?

V,A,H

Ent

roph

ospo

race

aeC

laro

ideo

glom

usG

lom

oid

sens

u la

toClaroideoglom

oidsensustricto

1

gt th

roug

h hy

pha

V,A,H

Alb

ahyp

haG

lom

oid

Claroideoglom

oidsensulato

1

gt th

roug

h hy

pha?

V,A,H

Visc

ospo

raG

lom

oid

Claroideoglom

oidsensulato

1

gt th

roug

h hy

pha

V,A,H

Ent

roph

ospo

raEntrophosporoid(intheneckofasaccule)

2

gt th

roug

h w

all?

V,A,H

Div

ersi

spor

ales

Div

ersi

spor

acea

eD

iver

sisp

ora

Glo

moi

dDiversisporoidsensustricto

1

gt th

roug

h hy

pha

V,A,H

Red

ecke

raG

lom

oid

(Diversisporo-)Redeckeroidsensustricto

1

gt th

roug

h hy

pha?

V,A,H

Oto

spor

aAcaulosporoid(ontheneckofsporiferous

saccule):otosporoidsensustricto

2

U

nkno

wn?

V,A,H

Tric

ispo

ra

Ent

roph

ospo

roid

Tric

ispo

roid

sen

su s

trict

o2

Unk

now

n?V,A,H

Sac

culo

spor

acea

eS

accu

losp

ora

Ent

roph

ospo

roid

Sac

culo

spor

oid

sens

u st

ricto

3

Unk

now

n?V,A,H

Pac

ispo

race

aeP

acis

pora

P

acis

poro

id2

gtthroughwall;multiply

lobe

d ge

rm s

truct

ure

V,A,H

Aca

ulos

pora

ceae

Kuk

losp

ora

Ent

roph

ospo

roid

Kuk

losp

oroi

d se

nsu

stric

to3

gtthroughwall;mono-

lobe

d, h

yalin

e ge

rm s

hiel

d (=orb)

V,A,H

Aca

ulos

pora

A

caul

ospo

roid

3

gtthroughwall;mono-(to

multiply)lobed,hyaline

germshield(=orb)

V,A,H


LE

195v o l u m e 2 · n o . 2

Gig

aspo

rale

sS

cute

llosp

orac

eae

Orb

ispo

ra

Scutellosporoid(onsporogenouscells,and

forminggermshields);Orbisporoids

ensu

st

ricto

3

gtthroughwall;mono-

lobe

d, h

yalin

e ge

rm s

hiel

d (=orb)

A,H

Scu

tello

spor

aS

cute

llosp

oroi

d

3

gtthroughwall;bi-lobed,

hyal

ine,

vio

lin-s

hape

d ge

rm

shie

ldA,H

Den

tiscu

tata

ceae

Fusc

utat

a S

cute

llosp

oroi

dFu

scut

atoi

d se

nsu

stric

to3

gtthroughwall;bi-lobed,

brow

n, o

val s

hiel

dA,H

Den

tiscu

tata

Scu

tello

spor

oid

Dentiscutatoidsensustricto

3

gtthroughwall;brow

ngerm

shie

ld w

ith m

ultip

le s

mal

l co

mpa

rtmen

tsA,H

Qua

tuni

caS

cute

llosp

oroi

dDentiscutatoidsensustricto

4

gtthroughwall;brow

nge

rm s

hiel

d w

ith m

ultip

le

com

partm

ents

A,H

Rac

ocet

race

aeC

etra

spor

aS

cute

llosp

oroi

dR

acoc

etro

id s

ensu

stri

cto

3


lobe

d, h

yalin

e ge

rm s

hiel

dA,H

Rac

ocet

raS

cute

llosp

oroi

dR

acoc

etro

id s

ensu

stri

cto

2


lobe

d, h

yalin

e ge

rm s

hiel

dA,H

Gig

aspo

race

aeG

igas

pora

Gigasporoid(onsporogenouscells,and

forminggermwarts)

1

gtthroughwall;germwarts

on in

ner s

pore

wal

l lay

erA,H

Arc

haeo

spor

omyc

etes

Arc

haeo

spor

ales

Am

bisp

orac

eae

Am

bisp

ora

Bimorph:Acaulo-&Glomo-am

bisporoid

3(Ac)

1(Gl)

Multiply-lobedgerm

structure(Ac)&gtthrough

hypha(Gl)

V,A,H

Arc

haeo

spor

acea

eA

rcha

eosp

ora

Bimorph:Acaulo-&Glomo-archaeosporoid

2(Ac)

1(G

l)

gtthroughwall;germtrunk

(Ac),&

gtthroughhypha

(Gl)?

A,H

Intra

spor

aBimorph:E

ntropho-&Glomo-intrasporoid

2(Ac)

1(G

l)

Unk

now

n?

A,H

Geo

siph

onac

eae

Geo

siph

onG

lom

oid

sens

u la

to

1

gt th

roug

h hy

pha?

Ass

ocia

ted

with

cy

anob

acte

ria

Para

glom

erom

ycet

es

Par

aglo

mer

ales

Par

aglo

mer

acea

eP

arag

lom

us

Glo

moi

d se

nsu

lato

1

gt th

roug

h w

all

A,H

oehl et al.ARTICLE


Figs 2–11.CharacteristicgerminationshieldsinGigasporaleswithgermpore(gp)asconnectionbetweensporecellcontentsandshieldsthatarepositionedonthesurfaceofthegerminalwall;germtubesemergefromgermtubeinitiations(gti).Fig. 2. Orbispora pernambucana (isotype,ZTMyc641)withmono-lobed,hyalinegermshield(orb).Figs 3–4. Scutellospora calospora(phototakenatINVAM)andS. dipurpurescens (holotypeOSC#83343)havebi-lobed,violin-shaped,hyalineshields.Figs 5–8. Racocetra coralloidea (type,OSC#31026),R. castanea (extype,ZTMyc4377),Cetraspora nodosa (isotype,DPP,Szczecin,Poland)andC. helvetica (isotype,ZTMyc3038)havewavy-like,multiplylobed,hyalineshields.Figs 9–11. Dentiscutataceaeshieldsareyellowbrowntobrown.Fig. 9. Dentiscutata reticulata(phototakenatINVAM)shieldswithmultiplesmallcompartments.Fig. 10. Quatunica erythropa(phototakenatINVAM)isassumedtobetheonlyknownspeciesinGlomeromycotawithfoursporewalls.Fig. 11. Fuscutata heterogama(extype,ZTMyc642)hasabi-lobed,ovaltoovoidshield.


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197v o l u m e 2 · n o . 2

Figs 12–21.Characteristicsporebasesandsubtendinghyphae(sh) inGlomeromycetesgenerawithglomoidsporeformation.Figs 12–13. Glomus ambisporum(Oehlcollection,fromBolivia)andG. aureum(type,ZTMyc822)withtwowalllayers(SWL1andSWL2),markedintrovertedwall thickening at sb and in sh, andasmall, bridgingseptum (sp).Fig. 14. Funneliformis coronatus (ex type,Oehl collection)with funnel-shaped sh and conspicuous sp;introvertedwallthickeningislacking.Fig. 15. Septoglomus constrictum(Oehlcollection,fromSwitzerland)withconspicuousseptumthatsometimesresemblesaplug.Fig. 16. Simiglomus hoi(Oehlcollection,specimenmountedatYorkuniversity)withcylindrical sh;shwallthickenedoverlongdistances;severalseptaeareregularlyobservedwithinthehyphae;nointrovertedwallthickeningat sb, pore at sbgenerallyopened.Fig. 17. Claroideoglomus etunicatum (Oehlcollection, fromBolivia)withfunnel/bill-shaped,whitesh;allEntrophosporaceae(syn.Claroideoglomeraceae)withcharacteristiccolorchangeofstructuralwalllayeratsb,ifsporesarepigmented.Fig. 18. Albahypha drummondii(type,DPP)withslightlyfunnel-shaped,whitesh.Fig. 19. Viscospora viscosa(extype,phototakenatINVAM)withcylindrical,whitehypha;sp within sh in some distance of sb;introvertedwallthickeningofsh at sp position, here not that obvious as usually found forthisspecies;viscosesporesurface.Fig. 20. Diversispora versiformis with short, fragile sh that is principally continuous with semi-persistent outermostsporewalllayer(SWL1)butnotwithstructurallayerSWL2(Oehlcollection,fromTibet).Fig. 21. Redeckera fulva (OehlexTrappecollection)withinflatingsh and conspicuous broad spexactlyatsporebase.

In Diversisporales and Glomerales,10generaexclusivelydifferentiatemono-walled,glomoid(9)orbi-walledpacisporoid(1)spores,allformedonsubtendinghyphae(Oehl&Sieverding2004,Oehlet al. 2011a).Themorphologicaldifferentiationofthe glomoid species is mainly based on the morphology of the subtending hyphae of the spores, and spore wall structure.Spores of Funneliformis, Glomus, Septoglomus, and Simiglomus species have subtending hyphae that are concolorous or slightly

lighter in colour than the spore wall (Table 1, Figs 12–16).Albahypha, Claroideoglomus, and Viscospora form spores in which the structural wall layer is continuous with the subtending hyphalwalllayer,butthesubtendinghyphaearehyaline(Figs17–19). Incontrast,Diversispora and Redeckera form spores whose structural wall layer is not obviously continuous with thehyphalwalllayer(Figs20–21);consequently,suchsporesappeartohaveincluded‘endospores’.

oehl et al.ARTICLE


Funneliformis, Glomus, Septoglomus, and Simiglomus can be separated by the structure of the spore base and subtending hyphae (sh). Glomus species often have an introvertedwall thickening (Oehl et al. 2011a; Figs 12–13)which is only otherwise seen in Viscospora.Funneliformis species generally have an easily visible septum in the area of the spore base, and their sh are regularly funnel-shaped to cylindrical (Fig.14).Septoglomus species have constricted to cylindrical sh, and usually there is a septum at the spore base (Fig.15). InSimiglomus, sh are cylindrical and thick-walled, and they have several septa some distance from the spore base (Fig. 16).Claroideoglomus has funnel- to bird-bill-shaped sh, with sh and shwallsthatare>2.5timeswiderat the spore base than somedistance from thebase (Fig.17).Albahypha has slightly funnel to bill-shaped sh and sh walls that are<2.0 timeswider at the sporebase thanatsomedistancefromthebase(Fig.18),andViscospora has cylindrical sh(Fig.19)withansh wall that may be thickened over large distances and may bear septa in the hyphae with introvertedwall thickenings in theareaof theseptum.In Diversispora, the sh are usually quite fragile and hyaline, distal to the pore closure at the spore base or in the sh(Fig.20).Redeckera species have a broad septum at the spore base(Fig.21),andthestructuralwalllayerdoesnotcontinuemorethan5–15µmintothesubtendinghypha,andthus,theshmayinflateatthisdistancefromthesporebase.

There are three bi-morphic genera with glomoid spore formation. Glomo-ambisporoid spores have a subhyalineto ochraceous, evanescent outer wall layer continuous with the outer acaulo-ambisporoid spore wall, while the second, structural layer is hyaline and continuous with the middle wall ofacaulo-ambisporoidspores(Spainet al.2006,Palenzuelaet al.2011).Glomo-archaeosporoidandGlomo-intrasporoidspores are among the smallest within Glomeromycota(ca.30µm),andthusdifficulttoobserve.

PersPectIves

Furtherseparationsofgeneraandfamiliescanbeexpectedin the near future since many species and several species groups have not yet been analyzed by molecular phylogenetic methods(e.g.Glomus group Ab1, sensu Oehl et al.2011a).Majoreffortsareneededtoproperlydescribethemorphologyof, in particular, small-spored Glomusspecies(Błaszkowskiet al. 2009a, b, 2010a, b), and it is difficult to predict howmorphological identification will develop in those fungi.Other recent progress has been made on Acaulospora species with pitted surface ornamentation, where several species, that superficially all resembled A. scrobiculata, havebeenseparated throughextensivemorphologicalandmolecularsporeanalyses (e.g.Oehlet al. 2006,2011e, f).The establishment of international and national collections of arbuscularmycorrhizalfungi,suchasINVAMinMorgantown(International Culture Collection of (Vesicular) ArbuscularMycorrhizalFungi,WestVirginiaStateUniversity,USA),CICGinBlumenau(InternationalCollectionofGlomeromycota at

FURB,SantaCatarinaState,Brazil),GINCO-BELinLouvain-La-Neuve(GlomeromycotaInVitroCollectionattheCatholicUniversity of Louvain, Belgium), or SAF in Zurich (SwissCollection of Arbsucular Mycorrhizal Fungi at AgroscopeART, Switzerland) will facilitate further progresses in thetaxonomy of glomeromycotean fungi that were thought tohave not enough criteria to morphologically separate them unequivocallyintothehigherleveltaxatheyphylogeneticallybelong to. Currently, several arbuscular mycorrhizal fungiare being described as new to science each year by an increasing numbers of research groups.A simple, butwelljustifiedconclusionisthat,asaresultoffutureconcomitantmorphological and molecular analyses, yet more higher level taxa will be proposed in this ancient fungal phylum, at alllevelsfromclassdowntogenus.

AcKNowledgeMeNts

Weacknowledgethehelpofmanycurrentandformerstudentsandtechnicians in Switzerland, Spain, and Brazil for outstanding support (especiallyDavidSchneider,RobertBösch,GiacomoBusco,LouisLawouin, Domingo Alvarez, Danielle Silva, Natália Sousa, andDanieleMagna). This study has been supportedwithin the SwissNational Science Foundation (SNSF) Project 315230_130764/1,by theSNSFProgrammeNFP48 ‘Landscapesandhabitatsof theAlps’,bytheSpanishMinistryofEnvironment(MMA-OAPN,project70/2005)andFAECA(JuntadeAndalucía,Spain,Project92162/11),andbytheFundaçãodeAmparoàCiênciaeTecnologiadoEstadode Pernambuco (FACEPE) and the UFPE which provided grantstoF.Oehlas‘visitingprofessor’,andFACEPEwhichalsoprovidedfinancialsupportforG.A.Silva.

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advances in glomeromycota taxonomy and classification

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