that the ECM habit was gained only once within
the order.
Fifteen genera and ca. 110 species are cur-
rently recorded in the order (Kirk et al. 2008 ),
but a number of new species have recently been
discovered, mainly from the Southern Hemi-
sphere (Henkel et al. 2011 ; Hosaka et al. 2008 ).
It has been demonstrated that many genera in
this order are polyphyletic. For example,Hys-
terangiumspp. are placed in both Hysterangia-
ceae and Mesophelliaceae (Hosaka et al. 2008 ).
Kirk et al. ( 2008 ) included Trappeaceae as the
fourth family of the order, but because the
genus Trappeais also polyphyletic and the
type species,Trappea darkeri, belongs to Phal-
lales (Hosaka et al. 2006 ), Trappeaceae should
not be included in Hysterangiales.
The biogeographyof the order was exten-
sively studied by Hosaka et al. ( 2008 ), who
demonstrated that the ECM lineages (Hyster-
angiaceae, Mesophelliaceae, and Gallaceaceae)
originated in the Southern Hemisphere (pre-
sumably east Gondwana), with a few range
expansions to the Northern Hemisphere.
Although some area relationships can be
explained by vicariance, many sister-group
relationships, such as those of taxa from Aus-
tralia and New Zealand separated by short
branches, can only be explained by long-
distance dispersal, suggesting that trufflelike
fungi are capable of crossing ocean barriers.
E. Trechisporales
Overview: Trechisporales K. H. Larss. (2007) is
a relatively small order with ca. 100 species and
8–13 genera. It was described only recently
(Hibbett et al. 2007 ), after DNA studies con-
firmed it as a distinct clade (Binder et al. 2005 ;
Larsson 2004 ; Matheny et al. 2007 ). The major-
ity of species in the order belong to the genus
Trechispora(includingCristelloporia,Scytino-
pogon), a highly diverse genus of mostly corti-
cioid fungi. The other genera contain only
corticioid fungi, with the exception of the
monotypic polypore genus Porpomyces. A
number of species in the order have an
anamorphic stage: Aegerita tortuosa for
Subulicystidium and Osteomorpha for
Trechispora. Considering that almost all species
in the order form inconspicuous fruiting bodies
that rarely get collected and identified, the
known species number is likely a fraction of
the true diversity.
Fruiting body morphology ranges from
clavarioid (Scytinopogon), stipitate hydnoid
(Trechispora thelephora), and resupinate poly-
poroid (Porpomyces,Trechispora) to corticioid
(Fig.14.5f–h). Most species either have small
spines (aculei) covering their hymenophore or
are completely smooth. Fruiting-body-asso-
ciated rhizomorphs are common, and all spe-
cies have light-colored fruiting bodies that
produce hyaline spores. Some dimitic species
are found inCristelloporia,Fibrodontia, and
Trechispora, but most species are monomitic
and bear clamps on all septa. Spore morphol-
ogy is very variable, from very long and narrow
spores of Subulicystidium to tiny ellipsoid
spores ofPorpomycesand spinose spores in
most species of Trechispora. Conspicuous
subulate cystidia are found inSubulicystidium
andTubulicium. Calcium oxalate crystals are
common on subicular hyphae ofTrechispora
and have been shown to be species-specific in
form (Larsson 1994 ).
Ecological diversity: most species in the
genus appear to be white-rot wood-inhabiting
(e.g.,Sistotremastrum) or soil-inhabiting (e.g.,
Porpomyces,Trechispora) saprotrophs.Trechi-
sporaspecies are difficult to grow with standard
culturing techniques for wood-decay fungi,
whereasSistotremastrumspp. pose no difficul-
ties. Dunham et al. ( 2007 ) reported root-
associated mycelial mats formed by Trechi-
spora, indicating a possible mycorrhizal associ-
ation, but further work is needed to confirm
this inference. One species (misidentified asT.
alnicola) has been reported as a grass parasite
(Wilkinson 1987 ).
Systematics: Larsson (2007b) divides the
order into two families: Hydnodontaceae Ju ̈lich
1982 (¼Subulicystidiaceae Ju ̈lich 1982) with
Fibrodontia,Luellia,Porpomyces,Subulicysti-
dium, Trechispora (including Cristelloporia,
Hydnodon),Tubulicium, and possiblySubuli-
cium; andSistotremastrumin its own, yet for-
mally unnamed, family. Telleria et al. ( 2013 )
produced a phylogeny of the order and
confirmed that Brevicellicium is also part
of the Hydnodontaceae. Larsson et al. ( 2011 )Agaricomycetes 395