Fungi Fimicoli Italici - Mycosphere-online journal

vate ascospores (with an equatorial groove
bordered by two ridges), and no anamorph,
Gymnascella an unappendiculate telaperidium,
sometimes with intervals of thick-walled
hyphae, ascospores smooth or with an equatorial
groove or ridge and/or polar thickenings,
and no or arthroconidial anamorphs, Gymnoascoideus,
a reticuloperidium lacking appendages,
smooth ascospores with a petaloid
arrangement inside the asci, and an arthroconidial
anamorph, Gymnoascus s.str., an appendiculate
reticuloperidium, smooth asco-spores,
and no anamorph.
Von Arx (1986) stated that the presence
or absence of a peridium and peridial appendages
are inadequate to circumscribe genera in
Gymnoascaceae, as some species can develop a
normal peridium in natural conditions and
completely lack it in subcultures. Starting from
this assumption, he conceived Gymnoascus in a
much broader sense than Currah (1985) and
emended it, including Acitheca, Arachniotus,
Gymnascella, and Gymnoascoideus in this
genus. He also accepted Narasimhella with its
often stipitate ascomata, unequally bivalvate,
hyaline rather than pigmented ascospores, and
asci not born from croziers.
Although von Arx (1987) attempted a
new classification of the Gymnoascaceae,
based on ascospore morphology, Currah’s
(1985) systematics was widely followed for
many years and re-examined with the introduction
of molecular techniques and phylogenetic
studies.
Unlike the assumption by Currah (1985,
1994) that Gymnoascaceae are polyphyletic,
data of Bowman et al. (1996) and Sugiyama et
al. (1999) from small subunit rDNA genes
sequences were consistent with a monophyletic
descendance of this family.
Subsequent studies (Sugiyama &
Mikawa 2001, Sugiyama et al. 2002), based on
large subunit ribosomal DNA sequences, confirmed
the monophyletic nature of the Gymnoascaceae,
but also proved that within a major
clade, species are grouped in four subclades,
Gymnascella is not monophyletic, and “the
ascospore morphology and phylogenetic structure
are incongruent”.
These latest results have induced
Lumbsch & Huhndorf (2007) to keep independent
the genera accepted by Currah (1985) and
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also include in Gymnoascaceae Narasimhella,
Kraurogymnocarpa Udagawa & Uchiyama
(1999), Mallochia Arx & Samson (1986), and
Orromyces Sur & G.R. Ghosh (Ghosh & Sur
1985). Kraurogymnocarpa and Mallochia have
bivalvate, respectively aculeate-tuberculate and
spiny ascospores, an atypical feature in Gymnoascaceae,
the former has also a reticuloperidium
with pointed appendages, the latter lacks
peridial hyphae. According to Sigler et al.
(1998) the monotypic Orromyces, with its
pitted ascospores and spiralate peridial appendages
is a synonym of Uncinocarpus queenslandicus
(Apinis & R.G. Rees) Sigler in
Onygenaceae.
A phylogenetic analysis of the ITS region
and 5.8S ribosomal DNA gene sequences (Solé
et al. 2002) proved that the majority of collections
isolated in pure culture, and classified by
Currah (1985) and von Arx (1986) as Arachniotus,
Gymnascella, Gymnoascoideus, Gymnoascus,
and Narasimhella, forms a monophyletic
clade. Molecular data, in combination
with morphological features, supported the proposal
to unify these taxa under the prior genus
Gymnoascus, to which a key was also provided
(Solé et al. 2002).
After Solé et al. (2002), I conceive Gymnoascus
in a broad sense, and under this name I
classify my Italian collections of Gymnoascaceae.
I also provide the following key to genera
of Gymnoascaceae, and to species of Gymnoascus
s.l. from Italy:
1) Peridium a complete net of thick-walled
hyphae (reticuloperidium) with pointed
appendages ............................................ 2
1*) Peridium of thin- or thick-walled hyphae.
Appendages, when present, different in
shape. Gymnoascus s.l. .......................... 3
2) Ascospores aculeate-tuberculate, bivalvate
......................... Kraurogymnocarpa
2*) Ascospores smooth .................... Acitheca
3) Peridium a complete net of thick-walled
hyphae. Ascospores 3V.5–4 × 3.5–4 ×
2.5–3 µm ................................................ 4
3*) Peridial hyphae thin-walled (telaperidium),
or thick-walled and forming an
incomplete net (incompositoperidium).
Ascospores larger .................................. 5