magnaporthales ( sordariomycetes , ascomycota ) contains important pathogens of cereals and grasses , including the rice blast fungus pyricularia oryzae ( magnaporthe oryzae ) , the take - all pathogen of cereals gaeumannomyces graminis , the rice stem rot pathogen nakataea oryzae ( magnaporthe salvinii ) and the summer patch pathogen of turf grass magnaporthiopsis poae ( cannon 1994 , thongkantha et al .
, about 200 species have been described in magnaporthales , of which approximately 50 % are pathogens of domesticated and wild monocotyledons .
the rice blast fungus has conidial ( asexual ) and ascosporic ( sexual ) morphs and the rice stem rot fungus produces sclerotial ( asexual ) , conidial ( asexual ) and ascosporic ( sexual ) morphs .
historically , such pleomorphy added to the difficulty in resolving taxonomic and nomenclatural problems associated with these species .
recent advancement in gene , transcriptome and genome sequencing of magnaporthales fungi resulted in robust phylogenies , which correspond well with the pathogenicity , ecology and biology of these species .
taxonomic revisions have been carried out for some of these taxa in recent publications ( luo & zhang 2013 , klaubauf et al . 2014 , luo et al .
, we list 28 accepted genera in magnaporthales and provide the rationale for the recommended genera if there is competition . a list of accepted generic names in magnaporthales , with the type species , is compiled in table 1 including references that serve as the basis for recognizing these genera .
this follows approval of their usage by the pyricularia / magnaporthe working group , without prejudice .
cases that require action to be approved by the nomenclature committee for fungi ( ncf ) are indicated by an asterisk in that table .
( a ) = a name typified by an asexual morph , ( s ) = a name typified by a sexual morph .
webster 1972 ( s ) cattaneo ( 1876 ) first named the rice stem rot pathogen as sclerotium oryzae based on the sclerotial morph . in the same paper he also described leptosphaeria salvinii , which was later recognized as the sexual morph of the same fungus ( tullis 1933 ) .
krause & webster ( 1972 ) then established the new generic name magnaporthe , typified by the ascosporic morph , to accommodate the rice stem rot pathogen as magnaporthe salvinii , as necessitated by the nomenclatural rules then in force .
sclerotium and leptosphaeria currently belong in basidiomycota and dothideomycetes respectively ( xu et al . 2010 ) , and are therefore not applicable to this sordariomycetous species .
nakataea and magnaporthe are congeneric and their type species , nakataea sigmoidea and magnaporthe salvinii , refer to the same species ( krause & webster 1972 ) .
subsequent to the ending of the separate naming of morphs of the same fungus species in 2011 , under art .
59.1 of the international code of nomenclature for algae , fungi , and plants ( icn ; mcneill et al . 2012 ) , luo et al .
( 2013 ) made a new combination for the rice stem rot fungus as nakataea oryzae , using the oldest legitimate generic name and species epithet .
those authors did not , however , formally propose the rejection or suppression of the later sexually typified names as currently required by art . 57.2 .
we note that it is proposed that this requirement be eliminated from the icn in 2017 ( hawksworth 2015 ) , but it is currently in force .
couch 2002 ( s ) in 1880 , saccardo established the generic name pyricularia based on the asexually typified p. grisea on crabgrass .
the rice isolates were designated as p. oryzae in 1892 by cavara , which now is known as the rice blast fungus . since then , over 50 species have been listed as pyricularia that cause blast diseases of monocotyledonous plants .
the sexual morph of pyricularia was first observed in 1970 from laboratory crossing experiments and believed to belong to magnaporthe because of the similarity in ascospore morphology ( hebert 1970 , barr 1977 , couch & kohn 2002 ) .
however , recent phylogenetic and phylogenomic analyses demonstrated that the sexually typified genus magnaporthe was polyphyletic .
the rice blast fungus is not congeneric with the type species of magnaporthe , m. salvinii , and the placement of the rice blast fungus in magnaporthe was based on an incorrect morphological identification ( zhang et al .
this is not a nomenclatural issue because the generic names magnaporthe and pyricularia are not congeneric and so do not compete for priority .
pyricularia and magnaporthe are currently both widely used generic names , and the rice blast fungus is an economically and scientifically important species that deserves much caution .
the pyricularia / magnaporthe working group has considered the possibility of conserving the name magnaporthe over pyricularia .
however , such conservation would require a change in the type species of the genus magnaporthe , and would cause numerous name changes for those species currently placed in pyricularia .
the asexually typified generic name pyricularia is the correct name for the rice blast fungus , which corresponds well with pathogenicity and ecological and evolutionary features .
the synonym magnaporthe oryzae , can nevertheless continue to be mentioned in publications as  pyricularia oryzae ( syn .
this practice will help to bridge a potential gap in the literature and knowledge for this important species .
( s ) the generic name clasterosphaeria , typified by c. cyperi , was established for the sexual morph of clasterosporium cyperi and includes only two names .
the generic name clasterosporium based on c. caricinum includes 158 names , many of which have been placed in other genera . whether or not clasterosphaeria cyperi is congeneric with clasterosporium caricinum is not known , although this seems likely given that both occur on cyperaceae .
if this is the case , use of the older , more commonly used generic name clasterosporium is recommended .
olivier 1952 ( s ) rather than harpophora gams 2000 ( a ) the generic name gaeumannomyces , typified by g. graminis , has long been used for the cause of take - all of wheat disease ( walker 1972 , 1980 ) .
harpophora was established for phialophora - like species that were known to be asexual morphs related to gaeumannomyces and magnaporthe but did not produce a sexual morph ( gams 2000 ) . with the change to one name , harpophora based on h. radicicola
is to be considered a synonym of gaeumannomyces , based on phylogeny ( luo et al .
2015b ) . given the greater number of species , priority , and numerous reports , we see no reason not to use the first published name , gaeumannomyces .
this work was partially supported by the national science foundation of the united states ( grant number deb 1145174 and deb 1452971 ) to ning zhang .
 the order magnaporthales comprises about 200 species and includes the economically and scientifically important rice blast fungus and  the take - all pathogen of cereals , as well as saprotrophs and endophytes . 
 recent advances in phylogenetic analyses of these fungi resulted in taxonomic revisions . in this paper 
 we list the 28 currently accepted genera in magnaporthales with their type species and available gene and genome resources . 
 the polyphyletic magnaporthe 1972 is proposed for suppression , and pyricularia 1880 and nakataea 1939 are recommended for protection as the generic names for the rice blast fungus and the rice stem rot fungus , respectively . the rationale for the recommended names is also provided . 
 these recommendations are made by the pyricularia / magnaporthe working group established under the auspices of the international commission on the taxonomy of fungi ( ictf ) . 
INTRODUCTION
RECOMMENDATIONS
ACKNOWLEDGMENTS