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Crous et al.
Clade 1 represented Strelitziana (Pseudocercospora-like
but with a separating cell between conidia and conidiogenous
cells) and Cyphellophora (Pseudocercospora-like but phialides
with flaring collarettes, situated directly on hyphae). Thedgonia
ligustrina (Pseudocercosporella-like, but conidia in chains)
represented Clade 2. Clade 3 included several isolates of
Pseudocercospora cantuariensis, which represents a novel genus,
distinguished from Pseudocercospora based on its broad conidial
hila and scars, as well hyaline mycelium, and the presence of
hyphopodia-like structures. Xenostigmina zilleri, characterised
as being Stigmina-like, but also having sympodial proliferation
of the conidiogenous cells, clustered in Clade 4, which was
basal to Cladosporium (Cladosporiaceae; Clade 5). Clade 6
represented several members of Teratosphaeriaceae, known
to have a wide range of anamorphs, including Microcyclospora.
Clade 7 represented species of Dissoconium (Dissoconiaceae),
distinct due to their dimorphic conidia that are actively discharged.
Clade 8 remains unresolved, and was represented by disjunct
elements appearing Zasmidium- and Pseudocercosporalike
in morphology, including Microcyclosporella. Clade 9 was
represented by several Mycosphaerella species such as M. laricina
(anamorph Pseudocercospora sp.), and Paracercospora egenula.
Paracercospora was separated from Pseudocercospora based on
a combination of characters, including pale olivaceous conidia, and
a minute thickening along the rim of its conidial hila and scars. Clade
10 included a diverse assemblage of genera. Two genera that differ
mainly based on their conidiomatal structure, Pseudocercosporella
and Septoria, clustered in this clade. Miuraea, a genus intermediate
between Cercospora and Pseudocercospora, also resided within
this clade. Clade 11 was represented by two coelomycetous species
of Sonderhenia that clustered basal to Clade 12. The latter included
a new genus with Pseudocercospora-like anamorphs, mostly
distinguished from Pseudocercospora s. str. by having species
with smooth, pale brown conidia, and the frequent production
of red crystals in agar (previously referred to in literature as the
Mycosphaerella heimii complex). Scolecostigmina (based on S.
mangiferae), which is characterised by verruculose conidia and
percurrently proliferating conidiogenous cells, clustered alongside
to Trochophora, characterised by brown sickle-shaped conidia with
three thick, dark septa. Passalora eucalypti formed a separate
lineage in Clade 13 that was adjacent to Pseudocercospora s. str.
in Clade 14. This clade included the type species, P. vitis that is
basal in this cluster. Although there was structure within the clade,
we regard it as representing a single genus, including Stigmina
platani, the type of Stigmina, Phaeoisariopsis (P. griseola), and
Pseudophaeoramularia (P. angolensis). Several isolates identified
from different countries as representing the same species based on
host, disease symptoms and general morphology, clustered apart
from one another. These collections were found to represent novel
cryptic species.
DISCUSSION
Several novel taxa were identified in this study on the basis
of phylogenetic analyses of the various gene regions together
with morphological examination of the specimens and isolates.
Recognised clades, as well as novel species and genera, are
described and discussed below. Where descriptions of known taxa
are freely available online in MycoBank or journals, they are not
repeated here, other than their generic circumscriptions.
Clade 1: Strelitziana and Cyphellophora
Strelitziana M. Arzanlou & Crous, Fungal Planet No. 8: 2006.
Conidiophores erect, solitary, arising from aerial and submerged
mycelium, subcylindrical, straight to geniculate-sinuous, pale
brown. Conidiogenous cells terminal, integrated, rejuvenating
percurrently, proliferating apically via several short, conspicuous
denticles; conidiogenesis holoblastic with rhexolytic conidial
secession. Conidia solitary, pale brown, smooth, long obclavate,
multi-euseptate; microcyclic conidiation present in culture.
Type species: Strelitziana africana M. Arzanlou & Crous, Fungal
Planet No. 8. 2006.
Notes: The genus Strelitziana presently accommodates four species
that are primarily distinguished based on their conidial dimensions.
These include S. africana, S. australiensis, S. eucalypti and S. mali
(Arzanlou & Crous 2006, Cheewangkoon et al. 2009, Zhang et al.
2009, Crous et al. 2010).
Cyphellophora G.A. de Vries, Mycopathol. Mycol. Appl. 16:
47. 1962.
Colonies (on OA) with moderate to rapid growth, velvety to lanose,
in various shades of grey; reverse black. Fertile hyphae pale brown,
sometimes with constrictions at the septa. Conidiogenous cells
phialidic, intercalary, sometimes on short side branches, each with
a short, lateral or terminal collarette. Conidia sickle-shaped, brown,
smooth-walled, transversely septate, adhering in small bundles
(from de Vries 1962).
Type species: Cyphellophora laciniata G.A. de Vries, Mycopathol.
Mycol. Appl. 16: 47. 1962.
Notes: The genus Cyphellophora, which is based on C. laciniata
(isolated from human skin; De Vries et al. 1986), appears to be
heterogeneous (Decock et al. 2003, Crous et al. 2007a, 2009a,
Cheewangkoon et al. 2009) and requires further study.
Clade 2: Thedgonia
Thedgonia B. Sutton, Trans. Brit. Mycol. Soc. 61: 426. 1973.
Foliicolous, phytopathogenic, causing discrete leaf spots.
Conidiomata fasciculate, punctiform. Mycelium internal, hyphae
subhyaline, septate, branched, forming substomatal stromata,
hyaline to pale brown. Conidiophores fasciculate, arising from
stromata, simple, rarely branched, subcylindrical, straight to
geniculate-sinuous, continuous to septate, smooth, hyaline to
pale yellowish green. Conidiogenous cells integrated, terminal,
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