Species of rust fungi of the genus Milesina (Pucciniastraceae, Pucciniales) are distributed mainly in northern temperate regions. They host-alternate between needles of fir (Abies spp.) and fronds of ferns (species of Polypodiales). Milesina species are distinguished based on host taxonomy and urediniospore morphology. In this study, 12 species of Milesina from Europe were revised. Specimens were examined by light and scanning electron microscopy for urediniospore morphology with a focus on visualising germ pores (number, size and position) and echinulation. In addition, barcode loci (ITS, nad6, 28S) were used for species delimitation and for molecular phylogenetic analyses. Barcodes of 72 Milesina specimens were provided, including 11 of the 12 species. Whereas urediniospore morphology features were sufficient to distinguish all 12 Milesina species except for 2 (M.blechni and M.kriegeriana), ITS sequences separated only 4 of 11 species. Sequencing with 28S and nad6 did not improve species resolution. Phylogenetic analysis, however, revealed four phylogenetic groups within Milesina that also correlate with specific urediniospore characters (germ pore number and position and echinulation). These groups are proposed as new sections within Milesina (sections Milesina, Vogesiacae M. Scholler & Bubner, sect. nov., Scolopendriorum M. Scholler & Bubner, sect. nov. and Carpaticae M. Scholler & Bubner, sect. nov.). In addition, Milesinawoodwardiana Buchheit & M. Scholler, sp. nov. on Woodwardiaradicans, a member of the type section Milesina, is newly described. An identification key for European Milesina species, based on urediniospore features, is provided.

Using molecular phylogenetic analyses (ITS) and morphological data obtained from light and electron microscopy, some European and North American species and genera placed or formerly placed in the genus Pucciniastrum in the Coleosporiaceae and Pucciniastraceae (Pucciniales) were taxonomically revised. The ITS analyses confirmed recent familiar concepts based on less variable markers except for the genus Hyalopsora. The family Pucciniastraceae is characterized by Abietoideae (Abies, Tsuga) aecial hosts. Pucciniastrum is described as a genus that consists of host-alternating species forming aecia on needles of Abies hosts, with special features of aeciospore morphology, and Onagraceae telial hosts. Other genera in the Pucciniastraceae are Calyptospora, Melampsorella, and additional taxa, which are currently provisionally placed in Pucciniastrum, but must be revised in future studies. Pucciniastrum epilobii (s. lat.), the type species of Pucciniastraceae, represents at least two species with different life cycles and urediniospore characteristics and is lecto- and epitypified. The family Coleosporiaceae, characterized by Pinoideae (Pinus) and Piceoideae (Picea) aecial hosts, contains Rosaceae rusts from three well-supported clades represented by three genera, Thekopsora, Quasipucciniastrum, and Aculeastrum gen. nov. Aculeastrum is characterized by coarsely arcuate ostiolar peridial cells and infects Rubus spp. telial hosts. The following new taxonomic combinations are proposed: Calyptospora ornamentalis comb. nov., Quasipucciniastrum ochraceum comb. nov., Q. potentillae comb. nov, Aculeastrum americanum comb. nov., and A. arcticum comb. nov. The results are discussed with emphasis on future studies in Pucciniastrum and the P. epilobii complex and on nomenclatural changes necessary for rust fungi due to the Shenzhen Code.

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