Generic names in Magnaporthales.

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

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 ). To date, 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. However, the phylogenies conflict with certain traditional generic concepts based on morphology. Magnaporthe and Gaeumannomyces, for example, were shown to be polyphyletic. Taxonomic revisions have been carried out for some of these taxa in recent publications (Luo & Zhang 2013, Klaubauf , Luo ). In this paper, 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.

Table 1.

Accepted generic names in Magnaporthales with type species, number of species in each genus, and gene or genomic resources. Names needing approval are indicated by an asterisk (*).

Taxa	Type species	Number of species	GenBank accession numbers for gene and genome sequence data**
MAGNAPORTHACEAE
Buergenerula Syd. in Annls mycol. 34: 392. 1936.	Buergenerula biseptata (Rostr.) Syd. 1936. (Metasphaeria biseptata Rostr. 1904).	4	Buergenerula spartinae: transcriptome (SRX798618) (Luo et al. 2015a).
Bussabanomyces Klaubauf et al. in Stud. Mycol. 79: 100. 2014.	Bussabanomyces longisporus (Bussaban) Klaubauf et al. 2014. (Pyricularia longispora Bussaban 2003).	1	Bussabanomyces longisporus: transcriptome (SRX798619) (Luo et al. 2015a).
Ceratosphaerella Huhndorf et al. in Mycologia 100: 941. 2008.	Ceratosphaerella castillensis (C.L. Sm.) Huhndorf et al. 2008.	2	Ceratosphaerella castillensis: ITS (EU527997), LSU (EU528003) (Huhndorf et al. 2008).
Ceratosphaeria Niessl in Verh. nat. Ver. Brünn 14: 203. 1876.	Ceratosphaeria lampadophora (Berk. & Broome) Niessl 1876.	34	Ceratosphaeria lampadophora: ITS (AY761088), LSU (AY346270) (Huhndorf et al. 2008).
* Clasterosporium Schwein. in Trans. Am. phil. Soc., New Series 4: 300. 1832.	Clasterosporium caricinum Schwein. 1832.	158
= Clasterosphaeria Sivan. in Trans. Brit. mycol. Soc. 83: 710. 1984.
Clavatisporella K.D. Hyde in Mycotaxon 55: 276. 1995.	Clavatisporella musicola K.D. Hyde 1995.	1
Falciphora J. Luo & N. Zhang in Mycologia 107: 643. 2015.	Falciphora oryzae (Z.L. Yuan et al.) J. Luo & N. Zhang 2015.	1	Falciphora oryzae genome (JNVV01000000) (Xu et al. 2014).
Gaeumannomyces Arx & D.L. Olivier in Trans. Brit. mycol. Soc. 35: 32. 1952.	Gaeumannomyces graminis var. graminis (Sacc.) Arx & D.L. Olivier 1952.	7	Gaeumannomyces graminis var. avenae: transcriptome (SRX798620) (Luo et al. 2015a); Gaeumannomyces graminis var. graminis: transcriptome (SRX798621) (Luo et al. 2015a); Gaeumannomyces graminis var. tritici: genome (ADBI00000000) (Okagaki et al. 2015).
= Harpophora W. Gams in Stud. Mycol. 45: 192. 2000.
Herbampulla Scheuer & Nograsek in Mycotaxon 47: 419. 1993.	Herbampulla crassirostris Scheuer & Nograsek 1993	1
Kohlmeyeriopsis Klaubauf et al. in Stud. Mycol. 79: 101. 2014.	Kohlmeyeriopsis medullaris (Kohlm., Volkm.-Kohlm. & O.E. Erikss.) Klaubauf et al. 2014.	1	Kohlmeyeriopsis medullaris: SSU(FJ176801), ITS(KM484852), LSU(FJ176801), RPB1(KM485069) (Klaubauf et al. 2014).
Magnaporthiopsis J. Luo & N. Zhang in Mycologia 105: 1021. 2013.	Magnaporthiopsis poae (Landsch. & N. Jacks.) J. Luo & N. Zhang 2013.	5	Magnaporthiopsis incrustans: genome (SRX795321), transcriptome (SRX798625) (Luo et al. 2015a);
			Magnaporthiopsis panicorum: transcriptome (SRX798626) (Luo et al. 2015a);
			Magnaporthiopsis poae: genome (ADBL01000000) (Okagaki et al. 2015);
			Magnaporthiopsis rhizophila: genome (SRX798599), transcriptome (SRX798627) (Luo et al. 2015a).
Muraeriata Huhndorf et al. in Mycologia 100: 948. 2008.	Muraeriata collapsa Huhndorf, Greif, Mugambi & A.N. Mill. 2008.	2	Muraeriata collapsa: LSU (EU527996) (Huhndorf et al. 2008).
* Nakataea Hara, Diseases Rice Plant, 2nd : 185. 1939.	Nakataea oryzae (Catt.) J. Luo & N. Zhang 2013.	7	Nakataea oryzae: genome (SRX798605), transcriptome (SRX798628) (Luo et al. 2015a).
= Magnaporthe R.A. Krause & R.K. Webster in Mycologia 64: 110. 1972.
Omnidemptus P.F. Cannon & Alcorn in Mycotaxon 51: 483. 1994.	Omnidemptus affinis P.F. Cannon & Alcorn 1994.	1	Omnidemptus affinis: transcriptome (SRX798629) (Luo et al. 2015a).
Pseudophialophora J. Luo & N. Zhang in Mycologia 106: 581. 2014.	Pseudophialophora eragrostis J. Luo & N. Zhang 2014.	8	Pseudophialophora eragrostis: transcriptome (SRX798634) (Luo et al. 2015a);
			Pseudophialophora panicorum: transcriptome (SRX798635) (Luo et al. 2015a);
			Pseudophialophora schizachyrii: transcriptome (SRX798637) (Luo et al. 2015a).
Pyriculariopsis M.B. Ellis, Demat. Hyphom.: 206. 1971.	Pyriculariopsis parasitica (Sacc. & Berl.) M.B. Ellis 1971.	1	Pyriculariopsis parasitica: LSU(DQ341514) (Klaubauf et al. 2014).
Slopeiomyces Klaubauf et al. in Stud. Mycol. 79: 102. 2014.	Slopeiomyces cylindrosporus (D. Hornby et al.) Klaubauf et al. 2014.	1	Slopeiomyces cylindrosporus: transcriptome (SRX798639) (Luo et al. 2015a).
OPHIOCERACEAE
Ophioceras Sacc., Syll. Fung. 2: 358. 1883.	Ophioceras dolichostomum (Berk. & M.A. Curtis) Sacc. 1883.	33	Ophioceras dolichostomum: genome (SRX798611) (Luo et al. 2015a);
			Ophioceras commune: transcriptome (SRX798630) (Luo et al. 2015a);
			Ophioceras leptosporum: transcriptome (SRX798632) (Luo et al. 2015a).
Pseudohalonectria Minoura & T. Muroi in Trans. Mycol. Soc. Japan 19: 132. 1978.	Pseudohalonectria lignicola Minoura & T. Muroi 1978.	13	Pseudohalonectria lignicola: genome (SRX798616), transcriptome (SRX798633) (Luo et al. 2015a).
PYRICULARIACEAE
Bambusicularia Klaubauf et al. in Stud. Mycol. 79: 104. 2014.	Bambusicularia brunnea Klaubauf et al. 2014.	1	Bambusicularia brunnea: ITS(KM484830), LSU(KM484948), ACT(AB274449), CAL(AB274482), RPB1(KM485043) (Klaubauf et al. 2014).
Barretomyces Klaubauf et al. in Stud. Mycol. 79: 104. 2014.	Barretomyces calatheae (D.J. Soares et al.) Klaubauf et al. 2014.	1	Barretomyces calatheae: ITS(KM484831), LSU(KM484950), ACT(KM485162), CAL(KM485231), RPB1(KM485045) (Klaubauf et al. 2014).
Deightoniella S. Hughes in Mycol. Pap. 48: 27. 1952.	Deightoniella africana S. Hughes 1952.	20
Macgarvieomyces Klaubauf et al. in Stud. Mycol. 79: 106. 2014.	Macgarvieomyces borealis (de Hoog & Oorschot) Klaubauf et al. 2014.	2	Macgarvieomyces borealis: SSU(DQ341511), ITS(KM484854), LSU(DQ341511), ACT(KM485170), CAL(KM485239), MCM7(KM009174), RPB1(KM485070), TEF1(KM009198) (Klaubauf et al. 2014, Luo et al. 2015a);
			Macgarvieomyces juncicola: transcriptome sequenced (SRX798624) (Luo et al. 2015a).
Neopyricularia Klaubauf et al. in Stud. Mycol. 79: 108. 2014.	Neopyricularia commelinicola (M.J. Park & H.D. Shin) Klaubauf et al. 2014.	1	Neopyricularia commelinicola: SSU(KM009211), ITS(FJ850122), LSU(KM484985), ACT(KM485175), CAL(KM485243), MCM7(KM009175), RPB1(KM485087), TEF1(KM009199) (Klaubauf et al. 2014, Luo et al. 2015a).
Proxipyricularia Klaubauf et al. in Stud. Mycol. 79: 109. 2014.	Proxipyricularia zingiberis (Y. Nisik.) Klaubauf et al. 2014.	1	Proxipyricularia zingiberis: ITS(KM484869), LSU(KM484986), ACT(AB274448), CAL(KM485244), RPB1(KM485088) (Klaubauf et al. 2014).
Pseudopyricularia Klaubauf et al. in Stud. Mycol. 79: 109. 2014.	Pseudopyricularia kyllingae Klaubauf et al. 2014.	3	Pseudopyricularia kyllingae: ITS(KM484876), LSU(KM484992), ACT(AB274451), CAL(AB274484), RPB1(KM485096) (Klaubauf et al. 2014).
Pyricularia Sacc. in Michelia 2: 20. 1880.	Pyricularia grisea Sacc. 1880.	55	Pyricularia grisea: transcriptome (SRX798638) (Luo et al. 2015a); genome (PRJEB7653 at http://genome.jouy.inra.fr/gemo/)
			Pyricularia oryzae:
			Genome (Dean et al. 2005).
Xenopyricularia Klaubauf et al. in Stud. Mycol. 79: 116. 2014.	Xenopyricularia zizaniicola (Hashioka) Klaubauf et al. 2014.	1	Xenopyricularia zizaniicola: transcriptome (SRX798640) (Luo et al. 2015a).

** Unpublished genome data are not listed.

RECOMMENDATIONS

(A) = a name typified by an asexual morph, (S) = a name typified by a sexual morph.

Use

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). Hara (1939) named the conidial morph of the species Nakataea sigmoidea. 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 ), 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 ), Luo 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.

Use

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 , Luo & Zhang 2013, Luo , Murata , Luo ). 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 name Pyricularia oryzae should therefore be used for the rice blast fungus. The synonym Magnaporthe oryzae, can nevertheless continue to be mentioned in publications as “Pyricularia oryzae (syn. Magnaporthe oryzae)”. This practice will help to bridge a potential gap in the literature and knowledge for this important species.

Use

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.

Use

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 ). Given the greater number of species, priority, and numerous reports, we see no reason not to use the first published name, Gaeumannomyces.

ACKNOWLEDGMENTS

This work was partially supported by the National Science Foundation of the United States (grant number DEB 1145174 and DEB 1452971) to Ning Zhang.