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Geneaand Genabeaare considered ectomycorrhizal (EM) symbionts of higher plants, but because of their hypogeous habit, dark coloration and the small size of their ascomata, relatively little is known about these genera. Ascomata of six morphological species of Geneaand one of Genabeawere frequently collected at a single site in xeric Quercuswoodlands of California’s Sierra Nevada foothills. While most collections were easily referred to known species, those putatively identified as Genea harknessiiand Genea arenariawere problematic. Genea harknessiicollections appeared relatively homogenous based on morphology, but significant ITS variation revealed by rDNA sequencing suggested cryptic species diversity. Specimens of G. arenariaapproximated the brief, original species description except for abundant clumps of septate setae formed at the apex of peridial warts. To verify the identity of this species we reexamined the holotype and analyzed morphology and ITS sequences of G. arenariaascomata from a wide geographic range. To authenticate the EM status of Geneaand Genabeawith Quercuswe collected healthy EM of Quercus douglasiiand Quercus wislizeniiand compared their ITS sequences to those from ascomata. We detected nine distinct ITS types of Geneaand Genabeaon roots. Two new species described here as Genea bihymeniatasp. nov. and Genea cazaresiisp. nov., were discovered during study of herbarium specimens. A phylogenetic analysis of 28 s rDNA from Geneaand Genabeaindicated three distinct lineages: Genea, Genabeaand a third represented by Genea intermedia. For the latter we propose Gilkeya gen. nov.to accommodate the single known species, Gilkeya compacta comb. nov.A dichotomous key to all known Genea, Genabeaand Gilkeyaspp. from western North America is presented.

Developing microsatellite markers for organisms with limited amounts of DNA can be difficult because sequence information is needed. To overcome this problem in the arbuscular mycorrhizal (AM) fungi Glomus etunicatumand Gigaspora gigantea, global amplification of the genomes of each species was performed with linker-adaptor-PCR from single spores. Amplified fragments were enriched for microsatellite motifs with 5′-biotinylated oligonucleotides and recovered by magnetic streptavidin beads. The recovered fragments were reamplified and separated on denaturing polyacrylamide gels, and 16 selected bands were excised, cloned and sequenced. Seven microsatellite motifs were detected from six clones (efficiency rate of 43.8%). Primers were designed for all putative microsatellite loci and most were successfully amplified from three single-spore preparations and from pools of five, 10 and 20 spores after global amplification. This approach, termed amplified fragment-length micosatellites (AFLM), might aid investigations of organisms that cannot or are not readily cultured in vitroand where DNA is a limiting factor for genetic studies. However, the technique also can be used to isolate microsatellite loci in any organism.

AbstractTo determine the identity and distribution of Armillariaspecies in California, we collected 589 isolates from managed areas (urban landscapes, orchards, and vineyards) and 20 natural forest types. From our collection of isolates, we identified A. mellea, A. gallica, A. nabsnona, and North American biological species X (NABS X). State-wide ranges of each species were estimated based on distributions of forest types from which they were collected. Only A. melleaand A. gallicaare widely-distributed in California; A. nabsnonaand NABS X appear to have restricted ranges. Armillaria melleais common in most regions of the state dominated by development, such as the Central Valley, the San Francisco Bay area, and Los Angeles. It was the only species, with the exception of a single isolate of NABS X, isolated from symptomatic hosts, including both forest trees and planted hosts. Armillaria melleadoes cause mortality in California forests, but large disease centers are rare. The distribution of A. gallicain California includes the greatest variety of forest types of all Armillariaspecies identified from our collection. Although it shares many forest types in common with A. mellea, A. gallicais extremely rare in developed areas. The range of A. nabsnonain California appears to be restricted to northern redwood forests. NABS X was only identified in high elevation red and white fir forests of the southern Cascades.