wood or leaf-litter substrates (e.g.,Lentinula,Maras-
mius, Xerula), but important plant pathogens also
belong here (e.g.,Armillaria,Moniliophthora). Schizo-
phyllaceae (Fistulina,Schizophyllum) and Lachnella-
ceae, dominated by cyphelloid forms, were recovered
as part of the marasmioid clade by Matheny et al.
( 2006 ) but as independent lineages in Binder et al.
( 2010 ). Resupinate genera (e.g.,Chondrostereum) also
occur in the marasmioid clade. Representative taxa
with recent phylogenetic studies include a general over-
view of marasmioid/gymnopoid fungi (Wilson and
Desjardin 2005 ),Omphalotus(Kirchmair et al. 2004 ),
Rhodocollybia(Mata et al. 2004 ),Marasmius, andCri-
nipellis(Kerekes and Desjardin 2009 ; Wannathes et al.
2009 ), and genera in theXerula/Oudemansiellacom-
plex (Petersen and Hughes 2010 ).
Hygrophoroid clade: in the analyses of Matheny
et al. ( 2006 ) this clade includes an expanded version of
Hygrophoraceae as traditionally defined plus the club
and coralloid fungi in the families Pterulaceae and
Typhulaceae. However, these two families were later
resolved as a separate lineage in Agaricales (Binder
et al. 2010 ). The family Hygrophoraceae was recently
extensively studied and redefined by Lodge et al. ( 2013 )
and now includes 18 genera, including the ECMHygro-
phorus, several segregates fromHygrocybesensu lato,
and a diverse clade of basidiolichens such asDictyo-
nemas. l. (Dal-Forno et al. 2013 ). All members of the
family are now assumed to be involved in some kind of
biotrophic relation, but its exact nature remains
obscure in most cases (Seitzman et al. 2011 ).
Pluteoid clade: this clade received weak support in
Matheny et al. ( 2006 ), and its limits and composition
require further study. The grouping of the Pluteaceae
andMelanoleucais well supported in most phylogenies
(Justo et al. 2011 ; Matheny et al. 2006 ). The aquatic
gasteromyceteLimnoperdonis also part of this core
pluteoid group in some analyses (Matheny et al.
2006 ). Amanitaceae, Pleurotaceae, and the genus
Macrocystidiaare, in some topologies, recovered as
closely related to the core pluteoid genera but
not always with statistical support or in a consistent
position. Important taxonomic revisions include arti-
cles on the Pluteaceae (Justo et al. 2011 ),Melanoleuca
(Sa ́nchez-Garcı ́a et al. 2013 ; Vizzini et al. 2012 ), Pleur-
otaceae (Thorn et al. 2000 ), and sequestrate forms in
Amanita(Justo et al. 2009 ). The iconic genusAmanita
has received considerable attention in relation to bio-
geography (Geml et al. 2006 ), invasive species (Pringle
et al. 2009 ), and transitions from saprotrophic to ECM
nutrition (Wolfe et al. 2012 ).
III. Conclusions
The previous edition ofThe Mycotaincluded a
preliminary phylogenetic outline of Homobasi-
diomycetes, with eight informally named
clades, that was based on 25 published and
unpublished analyses (Hibbett and Thorn
2001 ). The present chapter cites nearly 300
phylogenetic studies, many combining rRNA
and protein-coding genes, and a handful of
phylogenomic analyses. Twenty strongly sup-
ported, mutually exclusive clades of Agarico-
mycetes are recognized as orders. Numerous
studies, most of which are not cited here, have
addressed species- and genus-level relation-
ships within these groups. Nevertheless, the
classification of Agaricomycetes is far from
complete. There are weakly supported nodes
throughout the phylogeny, and the catalog of
described species is thought to be a tiny
fraction of the actual diversity in the group
(Blackwell 2011 ).
An overarching challenge of fungal system-
atics is to capture and integrate the massive
volumes of data flowing from taxonomy, phy-
logenetics, genomics, and molecular ecology.
Unfortunately, some common practices make
it difficult to combine the products of different
areas of research. For example, curated
sequence databases are important for the iden-
tification of environmental sequences (Ko ̃ljalg
et al. 2013 ), so it is unfortunate that many
recent species descriptions have been published
without sequences (Hibbett et al. 2011 ). It is
also unfortunate that only about 17 % of pub-
lished phylogenies, including those from fungal
studies, are available in electronic form (not
graphics files, but treefiles, in Newick or other
formats), which limits efforts to assemble max-
imally inclusive phylogenies and combine them
with taxonomic hierarchies (Collins et al. 2013 ;
Drew et al. 2013 ). To approach a comprehen-
sive phylogenetic classification of Agaricomy-
cetes and other Fungi, it will be necessary to
increase the pace of taxon discovery, encourage
researchers to generate and deposit sequences,
alignments, trees, and associated metadata
(Hyde et al. 2013 ), and create new bioinformat-
ics tools to synthesize the prodigious output of
the fungal systematics community.AcknowledgementsThe authors are grateful to Sigis-
fredo Garnica, Romina Gazis, Igor Grigoriev, Chris-
tiane Karasch-Wittmann, Urmas Ko ̃ljalg, FrancisAgaricomycetes 411