Hymenogaster macmurphyi and Splanchnomyces behrii are sequestrate species of Xerocomellus from the western United States.

Hymenogaster is an ectomycorrhizal genus of brown-spored sequestrate fungi that is related to the mushroom-forming genera Hebeloma and Alnicola (Agaricales). However, because of difficulties in morphological taxonomy of sequestrate fungi, Hymenogaster has become a polyphyletic repository for a variety of unrelated brown-spored sequestrate species. During studies of ectomycorrhizal ecology and sequestrate fungal evolution in the western USA, we encountered specimens of a morphologically unique species. It was originally described as Hymenogaster macmurphyi, but our morphological and molecular analyses indicate that it is not closely related to Hymenogaster. Phylogenetic analyses of multiple gene regions indicate that H. macmurphyi is actually a member of the Boletineae (Boletales, Basidiomycota) and is nested within the epigeous genus Xerocomellus, distantly related to any of the other known genera of sequestrate Boletales. While examining additional herbarium collections, we came upon isotype material of Splanchnomyces behrii, which represents a closely related species. Here we document the morphology and phylogenetic affinities of these unusual sequestrate Boletineae and transfer both species to Xerocomellus as X. macmurphyi and X. behrii. During our study, we also noted that the sequestrate taxon Rhopalogaster transversarius is nested within the epigeous genus Suillus.

Clarifying the butter Boletes: a new genus, Butyriboletus, is established to accommodate Boletus sect. Appendiculati, and six new species are described.

The butter boletes (Boletus s.l. sect. Appendiculati) are an economically important group of ectomycorrhizal fungi whose basidiocarps have a yellow tube layer that often bruises blue, yellow reticulate stipe, mild flavor and firm yellow-tinged flesh that may or may not turn blue when exposed. Morphological characters and molecular data (ITS and LSU) place this group in a separate phylogenetic clade from Boletus sensu stricto. Here we establish a new genus, Butyriboletus, to accommodate 14 species of butter boletes that range from Asia to Europe, north Africa and North America. We recombine eight previously described butter bolete species and we describe six new species: four from western USA (Bu. persolidus, Bu. primiregius, Bu. autumnigius, Bu. querciregius) and two from Yunnan, China (Bu. yicibus, Bu. sanicibus).

Linking mycorrhizas to sporocarps: a new species, Geopora cercocarpi, on Cercocarpus ledifolius (Rosaceae).

Mycorrhizal assemblages characterized by molecular data frequently differ from collections of mycorrhizal sporocarps at the same site. Geopora species are frequent mycobionts of ectomycorrhizal roots, but except for G. cooperi they are rarely identified to species by molecular methods. Among the mycobionts of ectomycorrhizas with Cercocarpus ledifolius (Rosaceae) was a fungal species with a 91% BLAST match to G. arenicola. To determine the species of Geopora we surveyed for hypogeous sporocarps under C. ledifolius at sites in southern Oregon where the Geopora mycorrhizas had been collected and identified by DNA sequences of the ITS region. We found sporocarps of a Geopora species with 100% BLAST match to the mycorrhizas. Morphological characters of a white hymenium, inrolled entire margin and large spores, along with a hypogeous habit and a mycorrhizal host of C. ledifolius, distinguished these specimens from previously described species. Here we describe a new species, Geopora cercocarpi.

Aquatic gilled mushrooms: Psathyrella fruiting in the Rogue River in southern Oregon.

A species of Psathyrella (Basidiomycota) with true gills has been observed fruiting underwater in the clear, cold, flowing waters of the upper Rogue River in Oregon. Fruiting bodies develop and mature in the main channel, where they are constantly submerged, and were observed fruiting over 11 wk. These mushrooms develop underwater, not on wood recently washed into the river. Substrates include water-logged wood, gravel and the silty riverbed. DNA sequences of the ITS region and a portion of the ribosomal large subunit gene place this fungus in Psathyrella sensu stricto near P. atomata, P. fontinalis and P. superiorensis. Morphological characters distinguish the underwater mushroom from previously described species. Fruiting bodies have long fibrillose stipes with small diameter caps. Immature stages have a thin veil that is soon lost. Gills lack reddish edges. Cystidia are ventricose with subacute apices. Spores were observed as wedge-shape rafts released into gas pockets below the caps. Underwater gills and ballistospores indicate a recent adaptation to the stream environment. This particular river habitat combines the characteristics of spring-fed flows and cold, aerated water with woody debris in shallow depths on a fine volcanic substrate. Based on molecular and morphological evidence we conclude that the underwater mushrooms are a new species, Psathyrella aquatica. This report adds to the biodiversity of stream fungi that degrade woody substrates. The underwater environment is a new habitat for gilled mushrooms.

Ectomycorrhizas of Cercocarpus ledifolius (Rosaceae).

PREMISE OF THE STUDY: Woody species in the Rosaceae form ectomycorrhizal associations, but the fungal symbionts are unknown. The species of fungi determine whether host plants are isolated from other ectomycorrhizal species in the plant community or linked with other trees through mycorrhizal networks. In this study we identified the fungi that form ectomycorrhizas with Cercocarpus ledifolius (curl-leaf mountain mahogany). • METHODS: Soil samples were collected under canopies of C. ledifolius. Ectomycorrhizas were described by morphology and by DNA sequences of the ITS region. Host species were confirmed by rbcL sequences. • KEY RESULTS: Sixteen species of fungi were identified from ectomycorrhizas of Cercocarpus ledifolius. The ectomycorrhizal community was distinguished by the presence of a Geopora species situated in the G. arenicola clade and by the absence of Rhizopogon, suilloids, and Sebacinales. Of the species on C. ledifolius, two also occurred on trees of Quercus garryana var. breweri and four on Arctostaphylos sp. • CONCLUSIONS: The presence of fungal species in common with other ectomycorrhizal hosts shows that C. ledifolius, Q. garryana var. breweri, and Arctostaphylos species could be linked by a mycorrhizal network, allowing them to exchange nutrients or to share inoculum for seedling roots and new fine roots. Single-host fungi limited to C. ledifolius may improve resource acquisition and reduce competition with other ectomycorrhizal hosts. The finding of a Geopora species as a frequent mycobiont of C. ledifolius suggests that this fungus might be appropriate for inoculating seedlings for habitat restoration.

Mycorrhizas on nursery and field seedlings of Quercus garryana.

Oak woodland regeneration and restoration requires that seedlings develop mycorrhizas, yet the need for this mutualistic association is often overlooked. In this study, we asked whether Quercus garryana seedlings in nursery beds acquire mycorrhizas without artificial inoculation or access to a mycorrhizal network of other ectomycorrhizal hosts. We also assessed the relationship between mycorrhizal infection and seedling growth in a nursery. Further, we compared the mycorrhizal assemblage of oak nursery seedlings to that of conifer seedlings in the nursery and to that of oak seedlings in nearby oak woodlands. Seedlings were excavated and the roots washed and examined microscopically. Mycorrhizas were identified by DNA sequences of the internal transcribed spacer region and by morphotype. On oak nursery seedlings, predominant mycorrhizas were species of Laccaria and Tuber with single occurrences of Entoloma and Peziza. In adjacent beds, seedlings of Pseudotsuga menziesii were mycorrhizal with Hysterangium and a different species of Laccaria; seedlings of Pinus monticola were mycorrhizal with Geneabea, Tarzetta, and Thelephora. Height of Q. garryana seedlings correlated with root biomass and mycorrhizal abundance. Total mycorrhizal abundance and abundance of Laccaria mycorrhizas significantly predicted seedling height in the nursery. Native oak seedlings from nearby Q. garryana woodlands were mycorrhizal with 13 fungal symbionts, none of which occurred on the nursery seedlings. These results demonstrate the value of mycorrhizas to the growth of oak seedlings. Although seedlings in nursery beds developed mycorrhizas without intentional inoculation, their mycorrhizas differed from and were less species rich than those on native seedlings.