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Armillaria possesses several intriguing characteristics that have inspired wide interest in understanding phylogenetic relationships within and among species of this genus. Nuclear ribosomal DNA sequence-based analyses of Armillaria provide only limited information for phylogenetic studies among widely divergent taxa. More recent studies have shown that translation elongation factor 1-α (tef1) sequences are highly informative for phylogenetic analysis of Armillaria species within diverse global regions. This study used Neighbor-net and coalescence-based Bayesian analyses to examine phylogenetic relationships of newly determined and existing tef1 sequences derived from diverse Armillaria species from across the Northern Hemisphere, with Southern Hemisphere Armillaria species included for reference. Based on the Bayesian analysis of tef1 sequences, Armillaria species from the Northern Hemisphere are generally contained within the following four superclades, which are named according to the specific epithet of the most frequently cited species within the superclade: (i) Socialis/Tabescens (exannulate) superclade including Eurasian A. ectypa, North American A. socialis (A. tabescens), and Eurasian A. socialis (A. tabescens) clades; (ii) Mellea superclade including undescribed annulate North American Armillaria sp. (Mexico) and four separate clades of A. mellea (Europe and Iran, eastern Asia, and two groups from North America); (iii) Gallica superclade including Armillaria Nag E (Japan), multiple clades of A. gallica (Asia and Europe), A. calvescens (eastern North America), A. cepistipes (North America), A. altimontana (western USA), A. nabsnona (North America and Japan), and at least two A. gallica clades (North America); and (iv) Solidipes/Ostoyae superclade including two A. solidipes/ostoyae clades (North America), A. gemina (eastern USA), A. solidipes/ostoyae (Eurasia), A. cepistipes (Europe and Japan), A. sinapina (North America and Japan), and A. borealis (Eurasia) clade 2. Of note is that A. borealis (Eurasia) clade 1 appears basal to the Solidipes/Ostoyae and Gallica superclades. The Neighbor-net analysis showed similar phylogenetic relationships. This study further demonstrates the utility of tef1 for global phylogenetic studies of Armillaria species and provides critical insights into multiple taxonomic issues that warrant further study.

The sections Pennatae and Spadiceae were chosen to test the agreement of current infrageneric classifications of Psathyrella (Psathyrellaceae, Agaricales) with molecular phylogenetic data and to evaluate the systematic significance of relevant morphological characters. The ITS and partial LSU regions of nu-rDNA from 53 specimens representing 34 species of Psathyrella were sequenced and analysed with parsimony-based and model-based phylogenetic methods. According to our analyses, the sections Pennatae and Spadiceae are polyphyletic and distributed across the family Psathyrellaceae, which is divided into at least five major groups. The first one comprises most of the included Psathyrella species and, probably, the whole genus Coprinellus. The second group is made up of Psathyrella gossypina and P. delineata. The third clade consists of the genus Coprinopsis and includes Psathyrella aff. huronensis and P. marcescibilis. The fourth clade is composed of two sister groups, the subgenus Homophron and the genus Lacrymaria, and the fifth group represents the genus Parasola including Psathyrella conopilus. These results are in agreement with neither the current circumscription of the two subgenera, Psathyra and Psathyrella, nor with the pre-sent disposition of the Psathyrellaceae. Taxonomically important morphological characters in the genus Psathyrella show a high degree of homoplasy. Although these characters are useful for species delimitation, and in some cases for the circumscription of sections, they appear insufficient for a phylogenetically correct generic concept.

Marasmiellus istanbulensis from the Belgrade Forest of İstanbul in Marmara Region of Turkey is described and illustrated as a new species based on both morphological and molecular data. A description with field and micromorphological illustrations and comparisons with morphologically close and phylogenetically-related species are provided. [ABSTRACT FROM AUTHOR]