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ABSTRACTThe genus Cerradoa(type species Cerradoa palmaea) was established in 1978 by Hennen and Ono and named after the Brazilian Cerrado biome. The holotype collected in Planaltina, Federal District, Brazil, belonged to the first rust fungus reported on palms (Arecaceae). For decades, the status of Cerradoaas a distinct genus has been regarded as doubtful, representing a synonym of Edythea(Uropyxidaceae) starting with the second edition of the Illustrated Genera of Rust Fungiin 1983. Our molecular phylogenetic analyses, as well as our morphological investigations, allowed us to reject this synonymy, leading to the reinstatement of Cerradoawithin the Pucciniaceae. Cerradoa, together with morphologically similar genera such as the newly established Pseudocerradoawith two species (Ps. paullulaand Ps. rhaphidophorae) infecting araceous hosts, the fern rust Desmella, and also P. engleriana, could not be assigned to any of the seven identified major lineages within the Pucciniaceae. Edythea, instead of being maintained as a member of the Uropyxidaceae, was herein placed in Pucciniaceae, shown phylogenetically in close relationship to Cumminsiella mirabilissima, both infecting the Berberidaceae. Additionally, our extensive phylogenetic analyses add guidance for future taxonomic revisions in the highly polyphyletic genus Pucciniaand other established taxa within the family Pucciniaceae.

Two new genera, Basidiopycnisand Proceropycnis, and two new species, Basidiopycnis hyalinaand Proceropycnis pinicola, are described. An integrated analysis of morphological, ecological, ultrastructural and molecular data indicates that the new taxa belong to the Atractiellales. Relevant characteristics of the new genera and species are discussed and compared with those of related taxa.

Molecular sequence data together with ultrastructural features were used to infer the phylogenetic position of Tuberculinaspecies. Additional ultrastructural characteristics were used to determine their mode of nutrition. We investigated ultrastructural morphology of the type species Tuberculina persicinaand determined base sequences from the D1/ D2 region of the nuclear large-subunit ribosomal DNA of the three commonly distinguished Tuberculinaspecies, T. maxima, T. persicinaand T. sbrozzii.Analyses of sequence data by means of a Bayesian method of phylogenetic inference using a Markov Chain Monte Carlo technique reveal the basidiomycetous nature of Tuberculina.Within the Urediniomycetes, Tuberculinaclusters as a sister group of Helicobasidium,closely related to the rusts (Uredinales). This phylogenetic position is supported by the uredinalean architecture of septal pores in Tuberculina.In addition, we present aspects of the ultrastructural morphology of the cellular interaction of Tuberculinaand rusts showing a unique interaction with large fusion pores, revealing the mycoparasitic nature of Tuberculinaon its close relatives, the rusts.

Tuberculinaspecies are mitosporic parasites of rust fungi. It was demonstrated recently that Tuberculinarepresents the asexual life stage of the plant-parasitic genus Helicobasidium.Here we reveal the host specificities of Tuberculinaand Helicobasidiumspecies on rust fungal hosts by means of infection experiments and molecular analyses. We inoculated species of the rust genera Chrysomyxa, Coleosporium, Cronartium, Gymnosporangium, Puccinia, Tranzscheliaand Uromyceswith conidia and with basidiospores of Helicobasidium longisporumand H. purpureumand with conidia of Tuberculina maxima, T. persicinaand T. sbrozzii.In addition we analyzed base sequences from the nuclear ITS region of 51 Tuberculinaand Helicobasidiumspecimens collected in the field together with the sequences from the Tuberculinainfections obtained by infection experiments. The resulting data show that at least six monophyletic lineages are within the Tuberculina/Helicobasidium-group that can be unambiguously distinguished by combining molecular and morphological characters and by specific host spectra of the Tuberculina-stage. This diversity opens up new vistas on the evolution of this exceptional mycoparasitic-phytoparasitic fungal group.

A new genus, Classicula, and a new species, Classicula fluitans, are described in the Urediniomycetes for the teleomorph of Naiadella fluitans. Classicula fluitansforms transversely septate basidia with subapically swollen sterigmata and long fusiform basidiospores. An integrated analysis of morphological, ultrastructural and molecular data indicates that Classicula fluitansis a member of the Urediniomycetes. Among the Urediniomycetes, Classicula fluitansshares the formation of simple septal pores associated with microbodies and tremelloid haustorial cells only with the hyphomycete Jaculispora submersa. In addition, in our molecular phylogenetic analyses with at least two representatives of all known urediniomycetous groups, Classicula fluitansappears together with Jaculispora submersain a statistically well-supported cluster. Accordingly, the family Classiculaceae and the order Classiculales are proposed to accommodate these fungi in the Urediniomycetes.

AbstractA new species of a dimorphic simple-pored auricularioid heterobasidiomycete, Occultifur externus, is described. This fungus was initially isolated in the unicellular stage and identified, on the basis of standard yeast identification tests, as the anamorphic pink yeast Rhodotorula minuta.This yeast was able to complete its life cycle on solid laboratory media. Two yeast cells conjugated, forming mycelium with clamp connections. The same generative hyphae produced clusters of four-celled basidia and characteristic swollen conidiogenic cells that released dikaryotic conidia. Haustorialike structures were formed. Nuclear DNA-DNA hybridization experiments revealed that O. externusis not the teleomorphic stage of R. minutaand molecular sequence data from the large subunit of the rDNA supported the affiliation of O. externusto the Naohidea-Sakaguchiaclade of the Urediniomycetes. Ultrastructural studies revealed the presence of simple septal pores. Cylindrical reticulate bodies were frequently found occluding them. These unique bodies could also be detected in O. internus, which supports the placement of both taxa in the same genus.