RESUMO
Phylogenetic analyses based on a three-locus nuclear data set (ITS1-5.8S-ITS2, the 5' end of the 28S, and the largest subunit of RNA polymerase I) supported the pagoda fungus (Podoserpula, Amylocorticiales) as a monophyletic group most closely related to species of Anomoporia, which is nonmonophyletic, and Amyloathelia. Phylogenetic relationships inferred from internal transcribed spacer (ITS) sequences of specimens sampled in Australia, Chile, China, Madagascar, and New Zealand divided Podoserpula into two major lineages: Clade A containing Australian and New Zealand collections designated P. pusio and the Chinese species P. ailaoshanensis, which have basidiospores with no reaction to Melzer's reagent, and Clade B, which includes a species described from Chile, P. aliweni, and specimens originating from Australia, Chile, Madagascar, and New Zealand with dextrinoid basidiospores. Podoserpula aliweni forms a unique branch in the phylogenetic tree and differs from its most closely related taxon by 1.8-2.1% in the ITS region. The new species exhibits a tree-like habit with a white to concolorous stipe-like base with the hymenophore's main subcylindrical axis bearing up to 18 superimposed pilei, slightly enrolled white margins shading from yellowish white to orange-yellow toward the center, and ellipsoid to broadly ellipsoid basidiospores measuring 4.0-4.5 × 3.5 µm. Ecologically, P. aliweni occurs during the rainy season, often gregariously on dried branches or wet soil under Nothofagus dombeyi or N. obliqua and has a distribution range of more than 600 km in southern Chile. This study extends the known distributional range and increases our knowledge on the phylogenetic diversity and taxonomy in Podoserpula.
Assuntos
Filogenia , Austrália , Chile , DNA Fúngico/genética , DNA Espaçador Ribossômico/genética , Análise de Sequência de DNARESUMO
The evolutionary history, divergence times and phylogenetic relationships of Uleiella chilensis (Ustilaginomycotina, smut fungi) associated with Araucaria araucana were analysed. DNA sequences from multiple gene regions and morphology were analysed and compared to other members of the Basidiomycota to determine the phylogenetic placement of smut fungi on gymnosperms. Divergence time estimates indicate that the majority of smut fungal orders diversified during the Triassic-Jurassic period. However, the origin and relationships of several orders remain uncertain. The most recent common ancestor between Uleiella chilensis and Violaceomyces palustris has been dated to the Lower Cretaceous. Comparisons of divergence time estimates between smut fungi and host plants lead to the hypothesis that the early Ustilaginomycotina had a saprobic lifestyle. As there are only two extant species of Araucaria in South America, each hosting a unique Uleiella species, we suggest that either coevolution or a host shift followed by allopatric speciation are the most likely explanations for the current geographic restriction of Uleiella and its low diversity. Phylogenetic and age estimation analyses, ecology, the unusual life-cycle and the peculiar combination of septal and haustorial characteristics support Uleiella chilensis as a distinct lineage among the Ustilaginomycotina. Here, we describe a new ustilaginomycetous order, the Uleiellales to accommodate Uleiella. Within the Ustilaginomycetes, Uleiellales are sister taxon to the Violaceomycetales.