The new species Puccinia telimutans causes Mexican potato rust disease of wild potatoes and shows a unique telial metamorphosis.

Puccinia telimutans is described as a new species of rust fungi (Basidiomycota, Pucciniales) and causal agent of Mexican potato rust disease of the endemic wild potatoes Solanum demissum and S. verrucosum from Mexico. It is microcyclic and produces telia that show a unique succession of one-celled, catenulate teliospores that germinate upon maturity, followed by resting teliospores that are pedicellate and two-celled. Puccinia telimutans appears to be restricted to Mexico and has formerly been confused with P. pittieriana, which causes common potato rust in South America.

A taxonomic revision of the genus Puccinia on Lycieae, a tribe of Solanaceae.

We present a taxonomic and phylogenetic study of Puccinia species (rust fungi) infecting tribe Lycieae (Solanaceae), with focus on the New World taxa. Phylogenetic analyses using nuclear (nuc) rDNA 5.8S-ITS2 (ITS2) and mitochondrial (mt) cytochrome oxidase subunit 3 (CO3) show that Puccinia species occurring on Lyciae are grouped in two major lineages, one New World and one Old World. We assessed the value of morphological traits and geographic range as important features for discriminating lineages. The morphology of teliospore pedicels and rust geographic ranges explained the relationships within this Puccinia species group. Four Puccinia species are recognized on Lycieae in the New World lineage and four in the Old World lineage. Puccinia tumidipes from North America is resurrected and P. dimidipes described as new from South America. In addition, P. spinulosa from Madagascar is reduced to a synonym of P. engleriana. Descriptions and a dichotomous key are presented for the accepted species.

Competing sexual and asexual generic names in Pucciniomycotina and Ustilaginomycotina (Basidiomycota) and recommendations for use.

With the change to one scientific name for pleomorphic fungi, generic names typified by sexual and asexual morphs have been evaluated to recommend which name to use when two names represent the same genus and thus compete for use. In this paper, generic names in Pucciniomycotina and Ustilaginomycotina are evaluated based on their type species to determine which names are synonyms. Twenty-one sets of sexually and asexually typified names in Pucciniomycotina and eight sets in Ustilaginomycotina were determined to be congeneric and compete for use. Recommendations are made as to which generic name to use. In most cases the principle of priority is followed. However, eight generic names in the Pucciniomycotina, and none in Ustilaginomycotina, are recommended for protection: Classicula over Naiadella, Gymnosporangium over Roestelia, Helicobasidium over Thanatophytum and Tuberculina, Melampsorella over Peridermium, Milesina over Milesia, Phragmidium over Aregma, Sporobolomyces over Blastoderma and Rhodomyces, and Uromyces over Uredo. In addition, eight new combinations are made: Blastospora juruensis, B. subneurophyla, Cronartium bethelii, C. kurilense, C. sahoanum, C. yamabense, Milesina polypodii, and Prospodium crusculum combs. nov.

Considerations and consequences of allowing DNA sequence data as types of fungal taxa.

Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.

Revision of the rust genus Uromyces on Cucurbitaceae.

This study revises Uromyces (Pucciniales or Uredinales) on the economically important plant family Cucurbitaceae and presents descriptions, illustrations and a key to aid determination of the 17 recognized species and four varieties. Seven species are described as new: Uromyces aimeae, U. aquiriensis, U. cucumivorus, U. infarctus, U. naucinus, U. saulensis and U. superstomatalis. Uromyces novissimus occurs on a number of tribes of Cucurbitaceae and is broadly circumscribed as a variable species that comprises four varieties. Variety cissampelidis, var. hellerianus and var. pentastriatus, are new combinations for U. cissampelidis, U. hellerianus and U. pentastriatus that have been regarded so far either as synonyms of U. novissimus or distinct species. The new name U. ernesti-ulei is proposed to replace the illegitimate name U. cayaponiae that refers to a uredinial state. It has been synonymized with U. novissimus as well but is considered a distinct species. Uromyces reynoldsii is reduced to a synonym of U. yakushimensis and a lectotype is selected for U. guraniae. Uromyces aimeae, U. neotropicalis and U. superstomatalis differ from the remaining species in superstomatal uredinia and telia and appear to be the first Uromyces spp. in which such sori are reported. The chytrid Olpidium uredinis is reported from three species, U. ernesti-ulei, U. guraniae and U. novissimus var. hellerianus, which are new hosts of this mycoparasite.

Rust fungi on Annonaceae II: the genus Dasyspora Berk. & M.A. Curtis.

Dasyspora gregaria, the single species of the allegedly monotypic rust genus Dasyspora (Basidiomycota, Pucciniales), was investigated by light microscopy and DNA sequencing (ITS1-5.8S-ITS2 region, partial LSU and SSU of the nuclear rDNA, mt cytochrome oxidase subunit 3). Both methods indicated that D. gregaria is not a single species but can be split in 11 distinct taxa, each of which appear confined to a single Xylopia species (Annonaceae) host. Herein nine of these are described as new. Both the phylogenetic analyses and morphology show that the species are grouped into two main clades designated Dasyspora gregaria and D. winteri. The first comprises D. gregaria, the type species of the genus, which is restricted to X. cayennensis, two new species on X. aromatica, D. segregaria from northern South America and D. echinata from Brazil. The second clade is formed by D. winteri, recombined from Puccinia winteri on X. sericea, and the new species D. amazonica on X. amazonica, D. emarginatae on X. emarginata, D. frutescentis on X. frutescens, D. ferrugineae on X. frutescens var. ferruginea, D. guianensis on X. benthamii, D. mesoamericana on X. frutescens, and D. nitidae on X. nitida. Dasyspora frutescentis and D. mesoamericana were not clearly distinguishable by their morphology and host associations but differed from another in their sequences and geographic distributions. They are considered cryptic species. An identification key and the distributions are given for all recognized species. Along with molecular data we discuss the systematic position of Dasyspora in the Pucciniales.

The Puccinia species of Berkheya (Asteraceae) with description of four new species from South Africa.

Puccinia species (rust fungi, Pucciniales, formerly Uredinales) occurring on Berkheya (syn. Stobaea) of Asteraceae are critically evaluated. Puccinia berkheyicola, P. stobaeae var. stobaeae and P. stobaeae var. woodii are recognized as valid species and varieties, while P. berkheyae is relegated to a synonym of P. stobaeae var. stobaeae. Lectotypes are selected for P. stobaeae var. stobaeae and P. stobaeae var. woodii. P. clanwilliamensis, P. garstfonteinii and P. monsfontium are proposed as new species for three rust fungi previously assigned to P. stobaeae; P. berkheyaephila is described as new on B. bipinnatifida. A key to the accepted species is presented.

Rust fungi on Annonaceae: the genus Sphaerophragmium.

Seven species of the rust genus Sphaerophragmium occur on members of the tropical plant family Annonaceae. Uropyxis gerstneri is recombined to S. gerstneri. A new species, S. xylopiae, is described from Xylopia acutiflora. The host plant of S. boanense is identified as Mitrella sp. Sphaerophragmium pulchrum is transferred to Dicheirinia. The anatomy of telia with teliospores and parasitizing mycelium is described and illustrated in detail. A new type of M-haustorium, which emanates laterally from intracellular hypha, is detected in S. monodorae. An identification key is given.

The rust mycobiota of southern Africa: species richness, composition, and affinities.

The rust mycobiota (Uredinales, Basidiomycota) of southern Africa (Botswana, Namibia, and South Africa) is analysed with regard to species richness, generic composition, and similarities to the rust mycobiotas of the remaining African continent and other regions of the world. Southern Africa is home to about 546 rust species: ca 522 species have been reported from South Africa, 73 from Namibia, and less than ten from Botswana. Thirty-two species were considered to be exotics. Two hundred and twenty-five of the species are restricted to southern Africa, suggesting an endemism rate of ca 44%. At present, the rust fungus:host ratio is 1:38.5, which is much lower than expected from other regions of the world. This low ratio may partly be due to under-exploration of the area, but the results presented here indicate that a natural paucity of rust fungi on certain, especially species-rich plant taxa centred in southern Africa and possibly environmental factors are more important reasons. The predominant genera are Puccinia and Uromyces accounting for ca 59% of the rust species. The genera Hemileia, Phakopsora and especially Ravenelia, centred in tropical regions, are well represented and sum up to 8% of the species. Members of Melampsoraceae and Phragmidiaceae, common in temperate regions of the Northern Hemisphere, are scarce. Most of the other 28 recorded teleomorph genera are only represented by three or less species. In an African context, most species are shared with central and east Africa (almost 16%). Only a few species are disjunct between southern and West Africa or Madagascar. Ca 10% of the species are shared only with other parts of the paleotropics, especially the Indian subcontinent. Disjunctions of native species with the New World, Australia/New Zealand, or Europe are rare.

Additions to the rust fungi of Argentina.

A contribution is made to the rust fungus flora of Argentina: Puccinia baccharidis-boliviensis, P. cordyceps, P. pucarae, and Aecidium hypseocharidicola are described as new species. Cionothrix praelonga, Frommeëlla mexicana var. mexicana, Phakopsora compressa, Prospodium peruvianum, Puccinia amphiospora, P. chaetochloae, P. liabi, P. pappophori, P. sanguinolenta, P. subaquila, Ravenelia havanensis, Uredo leonuri, Uromyces orbicularis, and U. cnidoscoli are new reports for Argentina. New observations on already known species were made: the aecia of Puccinia subaquila and aecia and uredinia of Uromyces cnidoscoli are described for the first time. Senecio hieronymi is a new host for Puccinia lagenophorae. Uredo leonuri belongs to the genus Coleosporium. Melilotus albus is a new host of Uromyces anthyllidis in Argentina.