Sarah E. Bergemann

Contrasting patterns of genetic diversity and population structure of Armillaria mellea sensu stricto in the eastern and western United States.

ABSTRACT Armillaria mellea infects hundreds of plant species in natural and managed ecosystems throughout the Northern hemisphere. Previously reported nuclear genetic divergence between eastern and western U.S. isolates is consistent with the disjunct range of A. mellea in North America, which is restricted mainly to both coasts of the United States. We investigated patterns of population structure and genetic diversity of the eastern (northern and southern Appalachians, Ozarks, and western Great Lakes) and western (Berkeley, Los Angeles, St. Helena, and San Jose, CA) regions of the United States. In total, 156 diploid isolates were genotyped using 12 microsatellite loci. Absence of genetic differentiation within either eastern subpopulations (theta(ST) = -0.002, P = 0.5 ) or western subpopulations (theta(ST) = 0.004, P = 0.3 ) suggests that spore dispersal within each region is sufficient to prevent geographic differentiation. In contrast to the western United States, our finding of more than one genetic cluster of isolates within the eastern United States (K = 3), revealed by Bayesian assignment of multilocus genotypes in STRUCTURE and confirmed by genetic multivariate analyses, suggests that eastern subpopulations are derived from multiple founder sources. The existence of amplifiable and nonamplifiable loci and contrasting patterns of genetic diversity between the two regions demonstrate that there are two geographically isolated, divergent genetic pools of A. mellea in the United States.

Toward a stable classification of genera within the Entolomataceae: a phylogenetic re-evaluation of the Rhodocybe-Clitopilus clade

Despite the recent molecular systematic analyses of the Entolomataceae (Agaricales, Basidiomycota), a robust classification of genera supported by morphological and phylogenetic evidence remains unresolved for this cosmopolitan family of pink-spored fungi. Here, a phylogenetic analysis for one of the two major clades (Rhodocybe-Clitopilus) was conducted using three nuclear protein-coding gene regions, the mitochondrial ATP synthase subunit 6 (atp6), the nuclear RNA polymerase subunit II (rpb2) and the nuclear translation elongation factor subunit 1-α (tef1). Five monophyletic groups are resolved with strong statistical support and a set of morphological features for delineation of genera is presented. In the revised classification proposed here, Clitopilus is retained, Rhodocybe is emended, two genera previously accepted as synonyms of Rhodocybe (Clitopilopsis and Rhodophana) are resurrected and Clitocella is described as new.

Evidence of natural hybridization among homothallic members of the basidiomycete Armillaria mellea sensu stricto

Populations of Armillaria mellea (Basidiomycota, Agaricales) across much of its range are heterothallic; homothallic populations occur only in Africa (A. mellea ssp. africana), China (China Biological Species CBS G), and Japan (A. mellea ssp. nipponica). Monosporous isolates of heterothallic A. mellea are haploid and their mating behaviour is consistent with the requirement of two different alleles at two mating-type loci (tetrapolar mating system) to create a diploid individual. In contrast, monosporous isolates of homothallic A. mellea are putatively diploid; they bypass the haploid phase by undergoing karyogamy in the basidium (a unique type of secondary homothallism/pseudohomothallism). In order to determine the genetic origin of this homothallism, we analyzed genetic variation of 47 heterothallic isolates from China, Europe, and North America, and 14 homothallic isolates from Africa, China, and Japan. Gene trees and mutational networks were constructed for partial mitochondrial gene ATP synthase subunit 6 (ATP6) and for the following nuclear genes: actin (ACTIN), elongation factor subunit 1-alpha (EFA), glyceraldehyde 3-phosphate dehydrogenase (GPD), and the RNA polymerase subunit II (RPB2). Homothallic isolates from Africa and Japan shared a common mitochondrial ATP6 haplotype with homothallic isolates from China, and are likely introductions. Homothallic isolates from China that shared a common mitochondrial haplotype with all European isolates did not share European nuclear haplotypes, as revealed by median-joining networks, but instead clustered with haplotypes from China or were intermediate between those of China and Europe. Such mitochondrial-nuclear discordance in homothallic isolates from China is indicative of hybridization between lineages originating from China and Europe.

Saxicolous species of Claudopus (Agaricales, Entolomataceae) from Australia

Claudopus rupestris, C. viscosus, and C. minutoincanus are described as new to science. All three species produce abundant, white basidiomata on the underside of granitic rocks and have a pileus that is sticky to the touch. Claudopus rupestris has unusual basidiospores, some of which are 4-angled. Claudopus viscosus and C. minutoincanus possess subcapitulate to capitulate pileocystidia and are morphologically similar to Entoloma jahnii of Europe.

Pouzarella (Agaricales, Entolomataceae) species from New South Wales (Barrington Tops National Park) and northeastern Queensland, Australia

Ten Pouzarella species are described from New South Wales and northern Queensland, Australia, of which eight (P. albostrigosa, P. farinosa, P. fusca, P. lageniformis, P. pamiae, P. parvula, P. pilocystidiata and P. setiformis) are new to science and two (P. debilis and P. lasia) are reported for the first time for Australia. Phylogenetic analyses of the mitochondrial small subunit rRNA (mtSSU), two variable domains (D1, D2) of the 25-28S large subunit rDNA (LSU), and a portion of the second largest subunit of the RNA polymerase (RPB2) gene support separation of these species into three clades. Morphological characters common to these clades are described, and a key to species based on the characters that are distinct between clades is included.

Three new Inocephalus species with cuboid basidiospores from New South Wales and Queensland, Australia

Three new Inocephalus species with cuboid spores are described from central New South Wales and northern Queensland, Australia. Inocephalus plicatus is diagnosed by its yellow pileus becoming plicate-striate and yellowish orange when mature, pungent odor, bitter taste, and pseudocystidia on all lamellar surfaces. Inocephalus hypipamee is differentiated by its brown umbonate pileus, white lamellae and stipe, obclavate cheilocystidia, subisodiametric basidiospores and clampless hyphae. Inocephalus parvisporus possesses small basidiospores and a Leptonia-like stature.

Five Leptonia species from New South Wales and Queensland, Australia

Descriptions and illustrations are provided for five Leptonia species. Three species are new to science: Leptonia boardinghousensis possesses unusual basidiomes colours, L. ambigua has subisodiametric basidiospores that atypically have obscure angles at the apex and a lignicolous habit, and L. omphalinoides is distinguished by its lignicolous omphalinoid tiny basidiomes. Two species were previously reported: L. poliopus from Europe and L. umbraphila comb. nov from the Seychelles.

A global view of Gyroporus: molecular phylogenetics, diversity patterns, and new species

ABSTRACT Gyroporus (Gyroporaceae, Boletales) is a highly diverse genus of poroid ectomycorrhizal mushrooms with a nearly worldwide distribution. Previous attempts to unravel the diversity within this genus proved difficult due to the presence of semicryptic species and ambiguous results from analysis of ribosomal RNA markers. In this study, we employ a combined morphotaxonomic and phylogenetic approach to delimit species and elucidate geographic and evolutionary patterns in Gyroporus. For phylogenetic analyses, the protein-coding genes atp6 (mitochondrial adenosine triphosphate [ATP] synthase subunit 6) and rpb2 (nuclear second largest subunit of RNA polymerase II) were selected based on their utility in studies of Boletales. We infer several distinct clades, most notably one corresponding to G. castaneus as a speciose Northern Hemisphere group, another unifying G. cyanescens and like entities, and a third group unifying G. longicystidiatus and a New World sister species. Also notable is the recovery of a sister relationship between the cyanescens and longicystidiatus clades. We formally describe five new species of Gyroporus, outline a number of provisional species, and briefly discuss distributional patterns. This study provides an important scaffold for future work on this well-known but poorly understood genus of fungi.

New leptonioid species from New South Wales and northeastern Queensland, Australia

Leptonia subpanniculus, L. newlingii, L. sabulosa, and L. substricta are described as new species based on morphological and molecular characters. Phylogenetic relationships and morphological simil ...

Entoloma species from New South Wales and northeastern Queensland, Australia

Seven new species in the Prunuloides clade of the Entolomataceae are described here: Entoloma hymenidermum is diagnosed by blackish blue basidiomata, isodiametric basidiospores and moderately broad pileocystidia; E. violaceotinctum has a violet-tinged pileus, violaceous-tinged stipe, and broad inflated pileocystidia; E. discoloratum possesses a subviscid yellow-tinged white pileus; E. kewarra is distinguished by its yellow pileus and stipe, both with a white and then eventually greenish yellow context; E. pamelae has a smooth, bright yellow, dry pileus; E. rugosiviscosum has a yellow-brown, rugose viscid pileus; and E. guttulatum is distinguished by lamellae with droplets that become reddish brown on drying.