IMA FuNgus · voluMe 3 · No 1: 81–86
doi:10.5598/imafungus.2012.03.01.08
Uwe Braun
ART I CLE
The impacts of the discontinuation of dual nomenclature of pleomorphic
fungi: the trivial facts, problems, and strategies
Martin-Luther-Universität, Institut für Biologie, Bereich Geobotanik und Botanischer Garten, Herbarium, Neuwerk 21, 06099 Halle (Saale),
Germany; corresponding author’s e-mail: uwe.braun@botanik.uni-halle.de
Abstract: The symposium “One fungus = Which name” held in Amsterdam 12–13 April
2012, addressed the drastic changes in the naming of pleomorphic fungi adopted by the 18th
International Botanical Congress in Melbourne in 2011. Possible solutions and ways to face
resulting problems were suggested. The fundamental change is that under the new rules
fungi in future will be treated nomenclaturally like plants and all other groups of organisms
ruled by the ICN, i.e. with one correct name for each species. Numerous discussions and
statements during the Symposium relected widespread anxieties that these rules could
negatively inluence taxonomic work on pleomorphic fungi. However, they are groundless,
being based on misunderstandings and confusion of nomenclature and taxonomy. With
pleomorphic fungi, taxonomists will in future have to answer the question whether different
morphs can represent one fungus (taxon), but this remains a taxonomic decision and has
nothing to do with nomenclature. Furthermore, the ICN does not and cannot rule on how
this decision is made. Thus it cannot provide rules based solely on methods involving
morphology in vivo or in vitro, molecular analyses, physiological and biochemical data,
inoculation experiments in pathogenic groups or any other methods or combinations of
them. It is up to the taxonomist to select appropriate methods and to decide which data
are suficient to introduce new taxa. Some future problems and strategies around the
application of anamorph- and teleomoph-typiied taxon names (genera and species), are
discussed here, using the recently monographed powdery mildews (Erysiphales) as an
example.
Key words:
anamorph
Article 59
Erysiphales
fungi
International Code of Nomenclature for algae
fungi, and plants
teleomorph
Article info: Submitted: 21 May 2012; Accepted: 1 June 2012; Published: 21 June 2012.
INTroducTIoN
During the KNAW-CBS Fungal Diversity Centre-organized
symposium “One fungus = One name” held in Amsterdam
in April 2011 ways to overcome dual nomenclature in
pleomorphic fungi were discussed culminating in the
“Amsterdam declaration” (Hawksworth et al. 2011) with
recommendations on how to deal with such fungi in future.
However, all aspects of this declaration did not receive
general acceptance, and opposing arguments were also
presented and published (Gams et al. 2011). A few months
later, the sweeping decisions of the 18th International
Botanical Congress in Melbourne, Australia, in July 2011
nulliied the opposing viewpoints, discussions and proposals
of the irst Amsterdam Symposium, rendering the Amsterdam
Declaration a ‘fait accompli’.
Various proposals to emend the International Code
of Botanical Nomenclature adopted by the Melbourne
Congress caused worldwide surprise to most mycologists
and can be considered revolutionary. The possibility to
publish valid diagnoses or descriptions of new taxa in English
besides Latin in future, the recognition of effective electronic
publications of new taxa under certain, deined conditions,
the mandatory requirement to deposit new fungal names in
a recognized repository, the renaming of the Code (now the
“International Code of Nomenclature for algae, fungi, and
plants”), and some other changes have been accepted by
the overwhelming majority of mycologists and are welcome.
Detailed discussions and explanations of the Melbourne
decisions have been published by Hawksworth (2011), Knapp
et al. (2011), and Norvell (2011). However, the abolition of the
special provisions of the previous Art. 59 of the ICN, allowing
the separate naming of morphs of pleomorphic fungi, which
was based on the most drastic ‘loor’ proposal concerning
this Article made by Scott A. Redhead (the Secretary of a
Committee appointed by the Vienna Congress in 2005 to
address this matter) among two other less drastic ones (Norvell
2011), was unexpected and a shock to most mycologists. After
the irst shock, followed by deeper objective considerations
of the consequences, advantages and disadvantages of the
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VOLUME 3 · NO. 1
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Braun
new rules for fungi I came to the conclusion that these drastic
changes are probably the best solution, since they provide
a good prospect of more stability and lexibility in future
and should prevent endless discussions and attempts to
modify the old Art. 59. However, reactions and comments by
numerous mycologists worldwide after the irst symposium
held in Amsterdam in 2011 (“One fungus = One name”) and
the Melbourne decisions, as well as various discussions
during the second Amsterdam conference in 2012 (“One
fungus = Which name?”) revealed widespread anxieties that
the new rules could negatively inluence future taxonomic
work with pleomorphic fungi. Viewed objectively, however,
most of the discussed problems and obvious reservations are
mainly based on a confusion of nomenclature and taxonomy,
i.e. they have nothing to do with the changed rules and relect
a widespread misunderstanding concerning the function of
the Code.
Various problems and open questions have already been
addressed by Gams et al. (2012), and the present paper
adds to the debate by addressing some further more minor
points. Strategies to overcome problems and to prepare the
mycological community for the enormous load of work caused
by the new rules are also discussed using powdery mildews
(Erysiphales) as an example. Comments, explanations and
proposals summarized in this paper are based on a lecture
given during the second Amsterdam symposium, discussions
during this meeting, and other critical notes, enquiries and
discussion between the irst and second Amsterdam symposia.
geNerAl NoTes, ProBleMs, ANd
sTrATegIes
special problems at the generic level
At the generic level, the new rules provide obvious advantages
and more freedom for the application of anamorph-typiied
genus names, which are now treated equally for priority
purposes, so that they may now be used as holomorph
names, i.e. for all morphs belonging to one fungus. Names of
an anamorph-typiied genus and a teleomorph-typiied genus
now compete nomenclaturally, if they belong to one taxon (“one
fungus”). If in this case the anamorph genus represents the
oldest valid and legitimate name, and it is the most widely used
and preferred, (e.g. Aspergillus, Cladosporium, Penicillium),
this name has priority over any younger meiosporic genus
and can be applied and used immediately as the name for
all morphs involved (holomorph). This applies, for instance,
in the case of Cladosporium Link 1816, v. Davidiella Crous &
U. Braun 2003. If anamorph-typiied genera are younger but
nevertheless preferred, proposals may be made in future to
accept these genus names. If a teleomorph-typiied genus
name is younger, it may also be proposed as the name for
all morphs. The procedures for such proposals, which can be
submitted as Lists of entire fungal groups, are outlined in Art.
4.13 and Art. 56.3 of the new version of the Code. Hence, in
future we have a high degree of lexibility in the application of
competing names at generic rank.
However, problems in the application of genus names
are usually connected with their typiication and taxonomic
implications. Anamorph as well as teleomorph genera are
82
ruled by typiication, i.e. by their type species. In cases where
we indeed have “one fungus” that deserves “one name”,
decisions regarding synonymy can be made on the basis of
molecular examinations (preferred), associated development
of anamorphs and teleomorphs in culture or any other
methods. This is not under the jurisdiction of the Code. As
the application of all fungal names is ruled by their types, it
is necessary to have convincing data for the type species
of both, the anamorph-typiied genus and the teleomorphtypiied genus, showing that the taxa concerned are, indeed,
congeneric. However, we have often only molecular or other
indications that certain anamorph and teleomorph genera are
probably congeneric merely based on data derived from nontype species. Fortunately in such cases, the synonymy of
these generic names can also be proposed. This is then just
a taxonomic decision leading to a proposal which in any case
is allowed and is not under the jurisdiction of the Code. The
Code only rules which name has to be adopted in this case of
facultative synonymy. Any treatments and concepts of genera
are possible, e.g. widening or reducing the circumscriptions,
and in an extreme case reducing them to a monotypic genus
only containing the type species, and these modiications are
only nomenclaturally, not taxonomically, ruled by the Code.
Other problems, also discussed during the Amsterdam
Symposium in April this year, concern the naming of often
numerous phylogenetically unproven species previously
assigned to a certain anamorph genus whose name, based on
its type species, is now considered synonymous with (part of)
a holomorph name. Allocations of species to certain genera
are taxonomic decisions, not ruled by the Code, and can be
done on the basis of any method, ranging from morphology to
molecular sequence analysis. If an anamorph-typiied generic
name is reduced to synonymy with a teleomorph-typiied
generic name, based on molecular data referring to their two
type species, it would be theoretically possible, but not in all
cases advisable, to re-allocate all species names previously
assigned to the anamorph genus to the teleomorph genus
name that now has priority. The phylogenetically unproven
species can be retained in the anamorph genus, which is
then only a facultative (heterotypic) synonym.
According to the new Art. 59, names published prior to
1 January 2013 for the same taxon, but based on different
morphs, are neither considered to be alternative names
according to Art. 34.2 nor superluous names according to
Art. 52.1, i.e. they are legitimate if not illegitimate due to other
reasons. Such synonyms are valid names, and valid names
remain available for use. Therefore, such anamorph generic
names may be retained and used for morphologically similar
species with unproven phylogenetic afinity. Another case
concerns the names of anamorph-typiied genera having
priority over competing names of teleomorph-typiied genera
or younger names being given priority following a proposal to
use them in future for all morphs. In these cases, all species
with unproven afinity may remain alongside type species
with proven phylogenetic afinity and other phylogenetically
proven species awaiting future clariication of their status
and afinity. This is possible and may be advisable since
any assignment of species to a genus is just a taxonomic
decision, as explained above. The only alternative would be
to re-allocate such unproven species to another genus, if
IMA FUNGUS
Impacts of the discontinuation of dual nomenclature
Facts and problems at the species level and
below
Changes in the Code become immediately effective when
ratiied by the inal Plenary Sesssion of an International
Botanical Congress, unless another date is speciied. In
the case of dual nomenclature, this ended on 30 July 2012,
from which date anamorph-typiied and teleomnorph-typiied
names compete on an equal nomenclatural footing. However,
a period of immunity to the end of 2012 was allowed so as
not to disrupt works in press which introduced new names for
different states of the same species. Thus, as Hawksworth
(2011: 158) stressed, “After 1 January 2013, one fungus
can only have one name, the system of permitting separate
names to be used for anamorphs then ends”. This statement
is not wrong, but needs to be clariied as it can cause
misunderstandings and confusion since it only refers to new
names introduced after 1 January 2013. As already mentioned
above, names based on different morphs for the same taxon
published before 1 January 2013, are to be considered
neither as alternative nor nomenclaturally superluous names
(according to Art. 59 of the Melbourne Code). Hence, such
names, including those of anamorphs, remain legitimate but
compete with teleomorph-typiied names.
Another question concerns the conditions applying when
one fungus can only have one name in future. The future
introduction of alternative names for different morphs is
only forbidden if an author deinitely states that the morphs
concerned belong to one fungus (taxon), independent of
the scientiic methods that led to this conclusion. If such a
statement (or taxonomic treatment) is lacking, possibly due
to uncertainty on the part of an author, it will still be possible
in future to give two names. Furthermore, other authors could
come to a more deinite conclusion. They might, for instance,
state that the merging of the two morphs in one fungus is
incorrect and not justiied, e.g. due to different cryptic taxa
VOLUME 3 · NO. 1
being involved and confused. Then the statement that only
one fungus is present cannot be upheld and the two morphs
must be given separate names. This is again solely a
taxonomic decision.
Another possible scenario concerns two different morphs
independently and validly described by different authors as
new species after 1 January 2013. When the two morphs
(species) later prove to be conspeciic, they have to be
merged under application of the priority rule, i.e. the younger
name just becomes a heterotypic synonym of the older one
but remains legitimate and valid. This is another example
where in future, after 1 January 2013, one fungus may have
two legitimate and valid names.
ART I CLE
available, or even to introduce a new genus for them, which
would result in numerous new genera and new combinations.
That is not quite what was intended by the new rules. In
such cases, the genera concerned remain paraphyletic or
even polyphyletic for a certain time until the phylogenetic
positions of all species assigned to these genera are known
and conirmed. This is acceptable and possible in the interim.
Monophyletic genera are the goal, but it will be a long time
before all fungal genera can be correctly assigned in this way.
For a considerable period of time we will need paraphyletic
and even polyphyletic genera. These must be recognized as
recently emphasized by Gams et al. (2012) with whom I fully
agree.
As already mentioned, concepts and circumscriptions
of genera, including phylogenetic aspects (monophyly,
paraphyly, polyphyly) are taxonomic decisions not under the
jurisdiction of the Code. First priority should be given to the
biodiversity at species level. All newly encountered species
have to be named so that they are determinable for all
users, ranging from ecologists, phytopathologists, physicians
engaged in human pathogenic fungi to researchers in
fungal genetics and physiology. The correct allocation to
an appropriate, whenever possible monophyletic, genus is
important, but has only secondary priority.
Implication of nomenclature and taxonomy
“One fungus = One name” is the premise of the changed Article
59 of the Melbourne Code, but the basic question is which
criteria should be used to decide whether different morphs
actually belong together as one fungus (taxon). It is solely up
to the taxonomist to determine these criteria and the methods
to answer this question (in this respect previous practices are
not different). This question cannot be answered by the Code,
and it is not the role of the Code to deine criteria for “one
fungus”. These criteria are tightly connected with technical
possibilities and methods of taxonomic work that develop
continuously and often rapidly. The Code simply rules the
nomenclature and was not created to interfere in taxonomic
questions and decisions. Any method is just a method and
not sacrosanct; even molecular results are often debatable
and open to interpretation. There are still many unanswered
questions, many of which may never be inally answered as
they depend on scientiic (technical) progress. For instance:
is a certain difference in the ITS sequences suficient? Do
we need several markers? If so, which markers and how
many at different taxonomic levels? What percentage of
genetic similarity of samples (populations) is suficient to
classify them as a single species? Do connections between
anamorphs and teleomorphs have to be suficiently proven by
molecular analyses? Etc. Different authors will have different
opinions and answers to these questions, and we cannot
expect to reach any kind of general agreement on them.
Authors will be inluenced by differences in circumscriptions
of taxa, e.g. whether they are sensu lato or sensu stricto,
the presence of different evaluations of certain characters,
the discovery of cryptic species, etc. Taxonomy is always a
combination of objective facts and subjective interpretations
of results. Hence, even uniform data may result in different
taxonomic conclusions by different authors. There are no
objective, universal criteria for, and deinitions of, taxonomic
ranks like order, family or genus, and the most dificult
lasting problem concerns the question “what is a species?”
Indeed, it is often quoted that a ‘species’ is in the eye of the
beholder! There is no general answer, but careful individual
taxonomic interpretations are necessary for any particular
taxon. Different taxonomic concepts and interpretations are
always in competition with each other, and the best solutions
prevail, following their eventual adoption by applicants and
users of names. We had good and bad taxonomy in previous
times and will have it in future, but whether it is good or bad
does not depend on the methods applied, and taxonomy
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Braun
Table 1. Current names in Erysiphales proposed for inclusion in a List of accepted names where there is an earlier anamorph-typiied name
available (placed in bold type and listed as a synonym).
erysiphe arcuata U. Braun, S. Takam. & Heluta, Schlechtendalia 16: 99 (2007).
Synonym: oidium carpini Foitzik, in Braun, Powdery Mildews Eur.: 222 (1995).
erysiphe azaleae (U. Braun) U. Braun & S. Takam., Schlechtendalia 4: 5 (2000).
Basionym: Microsphaera azaleae U. Braun, Mycotaxon 14: 370 (1982).
Synonym: oidium ericinum Erikss., Meddn Kungl. Landtbr.-Akad. Exper. 1: 47 (1885).
erysiphe buhrii U. Braun, Česka Mykol. 32: 80 (1978).
Synonyms: Erysiphe pisi var. buhrii (U. Braun) Ialongo, Mycotaxon 44: 255(1992).
oidium dianthi Jacz., Karm. Opred. Gribov 2 (Muchnisto-rosyanye griby): 461 (1927).
erysiphe caricae U. Braun & Bolay, in Bolay, Cryptog. Helv. 20: 46 (2005).
Synonyms: Oidium caricae F. Noack, Bol. Inst. Agron. Estado São Paulo 9: 81 (1898).
Acrosporum caricae (F. Noack) Subram., Hyphomycetes: 835 (1971).
oidium papayae Marta Sequ., Garcia de Orta, sér. Est. Agron. 18: 24 (1992).
erysiphe catalpae S. Simonyan, Mikol. Fitopatol. 18: 463 (1984).
Synonym: oidium bignoniae Jacz., Ezhegodnik 5: 247 (1909).
erysiphe celosiae Tanda, Mycoscience 41: 15 (2000).
Synonym: oidium amaranthi R. Mathur et al., Indian Phytopath. 24: 64 (1971).
erysiphe cruciferarum Opiz ex L. Junell, Svensk. Bot. Tidskr. 61: 217 (1967).
Synonyms: Erysiphe cruciferarum Opiz, Lotos 5: 42 (1855), nom. inval. (Art. 32).
E. pisi var. cruciferarum (Opiz ex L. Junell) Ialongo, Mycotaxon 44: 255 (1992).
oidium matthiolae Rayss, Palestine J. Bot., Jerusalem ser. 1: 325 (1940) [“1938–1939”].
erysiphe oehrensii (Havryl.) U. Braun & S. Takam., Schlechtendalia 4: 11 (2000).
Basionym: Microsphaera oehrensii Havryl., Mycotaxon 49: 259 (1993).
Synonym: oidium robustum U. Braun & Oehrens, Mycotaxon 25: 268 (1986).
erysiphe quercicola S. Takam. & U. Braun, Mycol. Res. 111: 819 (2007).
Synonym: Oidium anacardii Noack, Bol. Inst. Estado São Paulo 9: 77 (1898).
golovinomyces biocellatus (Ehrenb.) Heluta, Ukr. bot. Zh. 45(5): 62 (1988).
Basionym: Erysiphe biocellata Ehrenb., Nova Acta Phys.-Med. Acad. Caes. Leop.-Carol. Nat. Cur. 10: 211 (1821).
Synonyms: Erysibe biocellata (Ehrenb.) Link, Sp. Pl., edn 4, 6(1): 109, 1824) [as ‘biocellaris’].
oidium erysiphoides Fr., Syst. mycol. 3: 432 (1832).
golovinomyces magnicellulatus (U. Braun) Heluta, Ukr. bot. Zh. 45(5): 63 (1988).
Basionym: Erysiphe magnicellulata U. Braun, Feddes Repert. 88: 656 (1978).
Synonyms: E. cichoracearum var. magnicellulata (U. Braun) U. Braun, Nova Hedwigia 34: 695 (1981).
oidium drummondii Thüm., Mycoth. Univ 12: no. 1177 (1878).
golovinomyces sonchicola U. Braun & R.T.A. Cook, in Cook & Braun, Mycol. Res. 113: 629 (2009).
Synonym: oidium sonchi-arvensis Sawada, Bull. Dept. Agric. Gov. Res. Inst. Formosa 24: 34 (1927).
golovinomyces verbasci (Jacz.) Heluta, Ukr. bot. Zh. 45(5): 63 (1988).
Basionym: Erysiphe cichoracearum f. verbasci Jacz., Karm. Opred. Gribov 2 (Muchnisto-rosyanye griby): 224 (1927).
Synonyms: E. verbasci (Jacz.) S. Blumer, Beitr. Krypt.-Fl. Schweiz 7(1): 284 (1933).
oidium balsamii Mont., Ann. Mag. Nat. Hist., sér. 2, 13: 463 (1854).
leveillula rutae (Jacz.) U. Braun, in Braun & Cook, CBS Biodiversity Series 11: 205 (2012).
Basionym: Leveillula taurica f. rutae Jacz., Karm. Opred. Gribov 2 (Muchnisto-rosyanye griby): 417 (1927).
Synonyms: L. rutae (Jacz.) Durrieu & Rostam, Cryptog. Mycol. 5: 291 (1985) [“1984”]; comb. inval. (Art. 33.3).
oidium haplophylli Magnus, Verh. zool.-bot. Ges. Wien 50: 444 (1900).
Ovulariopsis haplophylli (Magnus) Trav., Atti Accad. Sci. Veneto-Trentino-Istriana 6: 1 (1913).
84
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Impacts of the discontinuation of dual nomenclature
Table 1. (Continued).
Phyllactinia ampelopsidis Y.N. Yu & Y.Q. Lai, Acta Microbiol. Sin. 19: 14 (1979).
Synonym: ovulariopsis ampelopsidis-heterophyllae Sawada, Bull. Dept. Agric. Gov. Res. Inst. Formosa 61: 8 (1933).
ART I CLE
Oidiopsis haplophylli (Magnus) Rulamort, Bull. Soc. Bot. Centre-Ouest 17: 191 (1986).
Phyllactinia chubutiana Havryl. et al. Mycoscience 47: 238 (2006).
Synonyms: oidium insolitum U. Braun et al., Sydowia 53: 35 (2001).
Ovulariopsis insolita (U. Braun et al.) Havryl. et al., Mycoscience 47: 238 ( 2006).
Phyllactinia gmelinae U. Braun & Bagyan., Sydowia 51: 1 (1999).
Synonyms: Phyllactinia suffulta var. gmelinae Patil, Curr. Sci. 30: 156 (1961); nom. inval. (Art. 36).
P. gmelinae Hosag. et al., Indian J. Trop. Biol. 1: 318 (1993); nom. inval. (Art. 37.6).
ovulariopsis gmelinae-arboreae Hosag. et al., Indian J. Trop. Biol. 1: 316 (1993).
Phyllactinia populi (Jacz.) Y.N. Yu, in Yu & Lai, Acta Microbiol. Sin. 19: 18 (1979).
Basionym: Phyllactinia suffulta f. populi Jacz., Karm. Opred. Gribov 2 (Muchnisto-rosyanye griby): 439 (1927).
Synonym: Ovulariopsis salicis-warburgii Sawada, Bull. Dept. Agric. Gov. Res. Inst. Formosa 61: 89 (1933).
based on molecular approaches is not per se superior over
morphotaxonomy.
Opinions and proposals to restrict descriptions of new
taxa, above all species, in future to those accompanied by data
of molecular sequence analyses have been discussed, but
they are unrealistic and must be refused. Molecular support
of new taxa is advisable, very useful and should be included
whenever possible, but its inclusion cannot and should not be
mandatory. This would be a kind of unacceptable “molecular
censorship” that would inhibit taxonomic work in several parts
of the world or would even force certain mycologists to give
up taxonomic work. Also, fungi of certain groups cannot be
cultivated at all; in other cases it may be very dificult to get
cultures or to extract DNA, and further to be conident that
the DNA is from the target fungus and not a contaminant.
Furthermore, there would be a drastic cut in taxonomic input
from amateur mycologists, who study various important
fungal groups in, for instance, agaricology, and lichenology.
Indeed, we need all available resources for the inventory of
worldwide fungal diversity. Demands to insert a particular
method like molecular sequence analysis in the Code as
being essential for valid publication would undoubtedly not
gain general acceptance. Such a requirement could only be
indirectly applied, outside the Code, by particular journals
making this a requirement for the acceptance of new species
descriptions. However, it is unrealistic to believe that such
policies could ever be a way of preventing publication of new
taxa not following such a dictat. Editors of other journals will
disagree, and publications of new taxa in books would not
follow the rule.
concepts for names in powdery mildews
(Erysiphales) – an example
A new updated taxonomic monograph of the powdery mildews
has recently been published (Braun & Cook 2012). Within this
group of obligate plant pathogens, clear connections between
anamorph and teleomorph genera (e.g. Blumeria with Oidium
s. str., Erysiphe with Pseudoidium, Golovinomyces with
VOLUME 3 · NO. 1
Euoidium) are evident and proven by means of morphology
and molecular sequence analyses. All anamorph-typiied
genera are younger than the corresponding teleomorphtypiied genera (except for Oidium) and hence will be
younger facultative synonyms in future, but nevertheless
they will remain legitimate and valid. Anamorph genera play
an important role in the taxonomy of powdery mildews and
relect phylogenetic relations within this fungal group. Indeed
they provided crucial evidence for the recent re-classiication
of all the holomorph genera. On the other hand, at species
level anamorph species (unlike the anamorph genera) and
particularly the conidial stages of powdery mildew species
are morphologically often poorly differentiated and of little
diagnostic value. Therefore, teleomorphs traditionally prevail
in the taxonomy at species level. Hence, in all cases it is
proposed to give preference to teleomorph-typiied names
when they are threatened by anamorph names.
There is only a single generic problem in powdery
mildews, viz. the anamorph genus Oidium Link 1824, with its
type species Oidium monilioides, which is the anamorph of
Blumeria graminis, the type species of the teleomorph genus
Blumeria Golovin ex Speer 1974. Hence, Oidium would be an
older name for Blumeria, and “Oidium graminis” would be the
correct name for the powdery mildew of grasses and cereals
in future; this is, of course, unacceptable, and Blumeria will
be proposed as the accepted generic name for this taxon.
Most powdery mildew anamorphs are morphologically
poorly differentiated at species level, and it is often dificult
to truly distinguish separate species in the absence of
the teleomorph. However, their relations to teleomorphic
genera are almost always clear. Host switches often occur
in glass houses, and also in nature, usually connected with
anamorph growth but lacking the teleomorph. Even results
of molecular sequence analyses are often not helpful here
due to a lack of data from other specimens for comparision
or other problems. Hence descriptions of anamorph-typiied
taxa should be avoided, also in future, but when new
descriptions are intended, they should only be based on
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striking morphological differences combined, if possible, with
molecular data, and the taxa concerned should preferably be
assigned to the existing anamorph genera, which can also be
used in future as they remain legitimate, valid, and available,
as already explained. Descriptions of anamorph-typiied new
species in Erysiphe, Golovinomyces, Neoërysiphe and other
teleomorph-typiied genera are in future of course also valid
and in accordance with the Code, but they should only be
proposed in absolutely clear, molecularly proven cases.
A recently found powdery mildew anamorph on Solanum
betaceum (tamarillo or tree tomato) in India is a striking
example. This host is phylogenetically closely related to S.
lycopersicum (tomato), and the anamorph found on tree
tomato is morphologically indistinguishable from Pseudoidium
neolycopersici (syn. Oidium neolycopersici) on tomato (Baiswar
et al. 2009). Nevertheless, this powdery mildew disease was
only recorded as Oidium sp. and not as O. neolycopersici
because reviewers refused the latter denomination without
inoculation results and/or molecular analyses. Therefore, cross
inoculation tests were later carried out and the tree tomato
powdery mildew was subjected to molecular examinations
based on ampliication of the rDNA ITS region, including the
5.8S rDNA, but, unfortunately, these new results also failed to
elucidate its taxonomy. The powdery mildew on S. betaceum
was unable to infect tomato and several other species of
Solanum, but the sequence derived from this powdery mildew
differed only in one base pair from that of Pseudoidium
neolycopersici. Is the tree tomato powdery mildew conspeciic
with the latter species and only a special form? Or is it a
separate species, morphologically indistinguishable from P.
neolycopersici, but biologically distinguished and genetically
distinct in one base pair in rDNA ITS sequence data? A inal
answer cannot yet be given. Incidently, in this case a study
of the morphology of this pathogen would now allow it to be
referred to the morphospecies Pseudoidium lycopersici as
listed in the updated monograph (Braun & Cook 2012). As
made apparent above, the anamorphic genus Oidum s. str.
belongs solely to Blumeria.
The Erysiphales in its current circumscription comprises
873 known species. The number of teleomorph-typiied species
names threatened by anamorph names is rather limited. Table
1 details the names that come into this category (all of them
will be put on a proposed List of accepted names according to
the new provisions of the Melbourne Code (Art. 14).
AcKNowledgeMeNTs
I am much obliged to Roger T.A. Cook, who critically checked the
whole text.
reFereNces
Baiswar P, Braun U, Chandra S, Ngachan SV (2009) First report of
an Oidium sp. [neolycopersici] on Solanum betaceum in India.
Australasian Plant Disease Notes 4: 32–33.
Baiswar P, Chandra S, Ngachan SV, Braun U, Takamatsu S, Harada
M (2012) Molecular Characterization of Oidium sp. on Solanum
betaceum in India. The Plant Pathology Journal (Korea): in press.
Braun U, Cook RTA (2012) Taxonomic Manual of the Erysiphales
(Powdery Mildews). [CBS Biodiversity Series no. 11.] Utrecht:
CBS-KNAW Fungal Diversity Centre.
Gams W, Humber RA, Jaklitsch W, Kirschner R, Stadler M (2012)
Minimizing the chaos following the loss of Article 59: Suggestions
for a discussion. Mycotaxon 119: 495–507.
Gams W, Jaklitsch W et al. (2011). A critical response to the
‘Amsterdam Declaration’. Mycotaxon 116: 501–512.
Hawksworth DL (2011) A new dawn for the naming of fungi: impacts
of decisions made in Melbourne in July 1011 on the future
publication and regulation of fungal names. IMA Fungus 2: 155–
162.
Hawksworth DL, Crous PW, Redhead SA, Reynolds DR, Samson RA,
Seifert KA, Taylor JW, Wingield MJ et al. (2011) The Amsterdam
Declaration on fungal nomenclature. IMA Fungus 2: 105–112.
Knapp S, McNeill J, Turland NJ (2011) Changes to publication
requirements made at the XVIII International Botanical Congress
in Melbourne – what does e-publication mean for you? Mycotaxon
117: 509–515.
Norvell LL (2011) Melbourne approves a new Code. Mycotaxon 116:
481–490.
IMA FUNGUS