North American matsutake: names clarified and a new species described.

Tricholoma matsutake, known widely as "matsutake," has great commercial and cultural significance in Japan. Because Japanese production is insufficient to meet the high domestic demand, morphologically similar mushrooms, thought by many to belong to T. magnivelare, are imported from western North America. However, molecular data produced since the early 2000s have indicated that more than one species of matsutake occur in North America and this raises the question of correct naming for the different species. To address this question, we assessed the phylogenetic diversity within North American matsutake based on nuc rDNA ITS1-5.8S-ITS2 (internal transcribed spacer [ITS] barcode) sequences, including newly obtained sequences from the type collections for Agaricus ponderosus and Armillaria arenicola, and morphological characters. Our results agree with earlier indications that three matsutake species occur in North America and allow us to clarify the correct application of names-T. magnivelare from the eastern USA and Canada, T. murrillianum from the western USA and Canada, and T. mesoamericanum from Mexico, newly described here. The existence of the three North American species is further supported by the results of evolutionary divergence analysis, geographical distributions, and morphological characters.

Polyozellus multiplex (Thelephorales) is a species complex containing four new species.

Geographic, morphological, and internal transcribed spacer (ITS)-based molecular review of collections identified as Polyozellus multiplex revealed that it is a complex of five phylogenetic species. Average spore size-either less or more than 7 × 6 µm-splits the complex into a small-spored group of two (P. multiplex and P. atrolazulinus) and a large-spored group of three (P. mariae, P. marymargaretae, and P. purpureoniger). Basidiocarps of the small-spored species are somewhat smaller than the large-spored ones, are various shades of blue, dark all the way to black, with brownish tomentum only in early growth, have dark context, and have pilei that tend to flare out at the edge. The large-spored species produce somewhat larger sporocarps, have light or lighter context than the pileipelis, and usually retain some brown on the mature pileipellis, the edge of which tends to curl like a cabbage leaf. All will darken or blacken with age. The species of the P. multiplex complex are distributed in the northern coniferous region, with the exception of Europe. One species (P. atrolazulinus) is known from three regions, eastern Asia, western North America, and northeastern North America. Two species are known from two regions: P. purpureoniger in eastern Asia and northwestern North America and P. multiplex in eastern Asia and eastern North America. Two species have been documented in one region only: P. mariae in northeastern North America and P. marymargaretae in western North America. A combination of location, macromorphology, and spore size will usually differentiate the species of the complex.

Patterns of nitrogen and carbon stable isotope ratios in macrofungi, plants and soils in two old-growth conifer forests.

• To further assess the usefulness of stable isotope ratios for understanding elemental cycling and fungal ecology, we measured δ15 N and δ13 C in ectomycorrhizal and saprotrophic macrofungi, plants, woody debris and soils from two old-growth conifer forests in Olympic National Park, Washington, USA. • Ecosystem isotope patterns were similar at the two forests, but differences existed that appear to reflect soil nitrogen availability and C allocation within the ectomycorrhizal symbioses. δ15 N and δ13 C of ectomycorrhizal and saprotrophic fungi differed in both forests, and a dual δ15 N/δ13 C plot provided the best means of distinguishing them. Within both groups, δ15 N and δ13 C differed among genera and species, and the difference in species composition was an important determinant of the different overall δ15 N of the ectomycorrhizal fungi at the two forests. • Variation in multiple ecophysiological traits such as organic N use, mycelial morphology and transfer of N to phytobionts appears to underlie the variation in the isotope signatures of ectomycorrhizal fungi. • The varied isotope signatures of ectomycorrhizal fungi suggest considerable functional diversity among them. Life-history strategies could provide a framework for interpreting these patterns.

Nitrogen and carbon stable isotope abundances support the myco-heterotrophic nature and host-specificity of certain achlorophyllous plants.

• Over 400 species of achlorophyllous vascular plants are thought to obtain all C from symbiotic fungi. Consequently, they are termed 'myco-heterotrophic.' However, direct evidence of myco-heterotrophy in these plants is limited. • During an investigation of the patterns of N and C stable isotopes of various ecosystem pools in two old-growth conifer forests, we sampled six species of myco-heterotrophic achlorophyllous plants to determine the ability of stable isotope ratios to provide evidence of myco-heterotrophy and host-specificity within these symbioses. • Dual-isotope signatures of the myco-heterotrophic plants differed from those of all other pools. They were most similar to the signatures of ectomycorrhizal fungi, and least like those of green plants. δ15 N values of the myco-heterotrophic plants correlated strongly and positively with those of putative mycobionts. • Used in conjunction with other techniques, N and C stable isotope ratios can be used to demonstrate myco-heterotrophy and host-specificity in these plants when other ecosystem pools are well characterized. They also appear promising for estimating the degree of heterotrophy in photosynthetic, partially myco-heterotrophic plants.