(2688) Proposal to conserve the name Phakopsora (Basidiomycota, Pucciniales) with a conserved type

Abstract

(2688) Phakopsora Dietel in Ber. Deutsch. Bot. Ges. 13: 333. 28 Aug 1895, nom. cons. prop. Typus: P. pachyrhizi Syd. & P. Syd. in Ann. Mycol. 12: 108. 15 Mai 1914, typ. cons. prop. The generic name Phakopsora has been widely used for species of rust fungi that occur on soybeans and other members of the Fabaceae such as P. pachyrhizi Syd. & P. Syd. causing Asian soybean rust and P. meibomiae (Arthur) Arthur causing Latin American soybean rust (Ono & al. in Mycol. Res. 96: 825. 1992). In addition, this genus includes a complex of species that cause serious leaf rust diseases on grapevine and other vitaceous plants such as P. ampelopsidis Dietel & P. Syd., P. euvitis Y. Ono, and P. vitis P. Syd. (Chatasiri & Ono in Mycoscience 49: 66. 2008; Okane & Ono in Mycoscience 59: 99. 2018), on cotton such as P. gossypii (Lagerh.) Hirats. (Gjaerum in Mycotaxon 24: 243. 1985) and on eucalypts such as P. myrtacearum McTaggart & al. (Maier & al. in Pl. Pathol. 65: 189. 2016). The original type of Phakopsora is a little-known species, P. punctiformis (Barclay & Dietel) Dietel (in Hedwigia 37: 217. 1898), which was initially described as Melampsora punctiformis Barclay & Dietel (in Hedwigia 29: 267. 1890) on Galium aparine in India. Although this name was the only species name mentioned in the protologue of the generic name (Dietel in Ber. Deutsch. Bot. Ges. 13: 333. 1895) and is thus the obligate type, it was not transferred to Phakopsora until Dietel (l.c. 1898) created the new combination P. punctiformis. The taxonomic placement of P. punctiformis is uncertain in that it has rarely been reported and is known only from China, India, Nepal and Russia (Farr & Rossman, Fungal Databases, U.S. National Fungus Collections [https://nt.ars-grin.gov/fungaldatabases/]. 2018). Almost no literature deals with P. punctiformis (Google Scholar [GS] exact phrase search: “Melampsora punctiformis” = 9, “Phakopsora punctiformis” = 12), and no DNA sequences exist for this species. In addition, this species lacks the uredinial paraphyses characteristic of most current species of Phakopsora (Sydow & Sydow, Monogr. Urediniearum: 3. 1915; Cummins & Hiratsuka, Ill. Gen. Rust Fungi, ed. 3. 2003) and is thus not representative of most of the species now considered to belong in the genus Phakopsora. As mentioned, Phakopsora pachyrhizi causes Asian soybean rust, a fungus of plant quarantine importance that is widely studied and well known (GS exact phrase search = 9180). Although reported for decades from Asia, the recent introduction of this fungus into the Western Hemisphere has resulted in considerable concern because of its virulence on the important soybean crop (Frederick in Phytopathology 92: 217. 2002). Recent molecular phylogenetic studies show that P. pachyrhizi and the closely related P. meibomiae cluster in a monophyletic clade with other economically important species of Phakopsora, such as P. myrtacearum (Beenken in Mycol. Progr. 13: 791. 2014; Maier & al., l.c.), as well as P. ampelopsidis and P. euvitis causing leaf rust of grapevine (Chatasiri & Ono, l.c.; Okane & Ono, l.c.). To bring the definition of the generic name Phakopsora in line with its current usage, we propose to conserve Phakopsora with a new type, P. pachyrhizi, the cause of the globally important disease Asian soybean rust. MCA, https://orcid.org/0000-0001-8742-6685; AYR, https://orcid.org/0000-0002-8191-2663; YO, https://orcid.org/0000-0002-8247-7245; LAC, https://orcid.org/0000-0002-6131-7736 We appreciate the assistance of Paul Kirk, CABI, in determining the correct place and date of the publication of Phakopsora punctiformis. USDA is an equal opportunity provider and employer.