This tree is an unrooted branchand bound parsimonyanalysis of 4 genetic loci: chitin synthase, GPD, ITS, and IGS. Bootstrap values are on the branches. Other analyses not shown suggest that the root should be on the longest branch.

The molecular systematics of the Western U.S. edible ectomycorrhizal mushrooms in the Boletus edulis complex, Boletus section Edules.

Francisco J. Camacho& Tom Bruns

Boletus fibrillosus ThiersType locality: Jackson State Forest, Mendocino Co. CaliforniaHabitat: Coastal and Montane moist coniferous forest of the Western U. S.Host tree (potential): Abies species, Pinus species, Picea speices, Pseudotsuga menziesii, Quercus speciesDistribution: Along the west coast from Lincoln Co. Oregon in the north and Santa Cruz Co. California in the south. In the Cascades from Linn Co. Oregon in the north to the Sierra Nevada Tuolumne County in the south. Also known from one montane site in the Oregon Coast Range on Mary's Peak, Benton Co. Oregon. Probably extends into Washington and British Columbia, Canada.Phenology: Late August to October in the Sierra Nevada and Cascades, October and November during the rainy season along the coast, and October and November in the Oregon Coast Range.

Gastroboletus subalpinus Trappe & ThiersType locality: Cloud Cap, Hood River Co. OregonHabitat: Montane coniferous forests of the Oregon Cascades and the California Seirra Nevada mountainsHost tree (potential): Abies species, Pinus species, Tsuga mertensianaDistribution: Northern limit is just south of the Columbia River in the Oregon Cascades, Hood River Co, extending South through the Cascades into the Seirra Nevada of California all the way to Fresno Co. One collection is known from the Kalamath MountainsPhenology: August in the southern portion of the range and September and October in the northern areas.

Boletus mottiae ThiersUsually misidentified as B. aereus Bulliard: Fr., which is a European speciesType locality: Grass Valley, Nevada Co. California Habitat: In oak, madrone, and mixed woodlands in the foot hills of the Sierra Nevada, Cascades and thoughout the coastal mountains.Host tree (potential): Quercus species, Pinus species, Pseudotsuga menziesii, Arbutus menziesii, Chrysolepis chrysophylla, Lithocarpus densiflorusDistribution: Known from the coastal mountains of California from San Mateo Co. north to the coastal mountains of Oregon to Lane Co. Also occuring on the western foothills of the Sierra Nevada and North to the Oregon Cascades, Lane Co. Possibly throughout the Kalamath mountains and probably up to Washington and British Columbia, Canada. Phenology: Late Fall, October throught December.

Boletus sp. nov. (Spring King) Habitat: Montane coniferous forests of the Sierra Nevada, Cascades, and Rocky Mountains of Idaho. Host tree (potential): Abies species and Pinus species. Distribution: Southern Sierra Nevada, Fresno Co. north to Descutes Co. in the Oregon Cascades probably extending into Washington and British Columbia, Canada. Also know from Idaho. Phenology: Spring, May and June.

Boletus edulis Bulliard: Fr.Type locality: FranceDistribution: Throughout the Northern Hemisphere

In Western North AmericanHabitat: Coastal and Montane moist coniferous forests. Also Hardwood riparian forests of the Willamette Valley. Host tree (potential): Picea species, Pinus species, Abies species, Populus balsamifera spp. trichocarpa Distribution: Along the Coast the most southern collection is from Monterey Co. In the mountains it is reported as far south as Fresno Co. in the Sierra Nevada. It may extend farther south. To the north it extends up to Alaska and east into the Rocky Mountains.Phenology: In Montane habitats it may fruit in mid August until October. On the Coast it may be fruiting in mid September through November with one reported fruiting in the Southern end of the range in early March.

Boletus aestivalis (Paulet) Fr. NOT in Western North AmericaType locality: EuropeHost tree (potential): Fagus species and Quercus speciesDistribution: Europe and AsiaPhenology: summer and early autumn

Boletus barrowsii Thiers & SmithType locality: Jacob Lake, Kaibab National Forest, Coconino Co. Arizona Habitat: Coastal live oak and mixed coniferous and hardwood forests of montane areas.Host tree (potential): Pinus species, Abies species, Quercus species. Distribution: In California it is reported from coastal areas from Marin Co. to the island Santa Rosa in the Channel Islands. It probably extends to the southern reaches of California, San Diego Co. and into Mexico. It is found east through Arizona and New Mexico. As far South as Mexico and north from New Mexico, through Colorado and into Idaho. Phenology: California coastal speciems have been collected in May and November, montane collections are found in August.

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The Boletus edulis species complex is probably the most widely sought after group of edible mushrooms in the world. Because of this popularity many cultures have given these mushrooms common names; such as Steinpilz (German), porcino (Italian), cepe de Bordeaux (French), penny bun (English), zhutui mo (Northern Chinese), and dajiao gu (Southern Chinese). These species are responsible for millions of dollars in commerce each year. These mushrooms have avoided many attempts to be cultivated. They are only collected for comsumption from natural forests and woodlands, where they must form mutualistic mycorrhizal associations with trees. Probably because they are all edible, several distinct species are often lumped under Boletus edulis. Although they may all be considered B. edulis, the different species can have different values on the market. For example, mushrooms from Italy are considered gastronomically better and are more expensive that those from China. This difference in culinary qualities is almost certainly explained by different species in each region. The unifying features that distinguish this group of mushooms (Boletus section Edules) are the pored hymenium (spore producing tissue), reticulate stipe, white membranous tissue covering the pores early in the development of the mushroom, and the mild raw taste. The goal of this research is to investigate and understand the biology (taxonomy, systematics, ecology, and physiology) of the species in the Boletus edulis complex. The results presented here define the Western North American species.

AcknowledgementsWe would like to thank the following people who helped with this project

Jamie L. Platt, Erik Lilleskov, Jenny Tan, Lauren Thompson, Rasmus Kjoller, LIsa Grubisha, Lisa Bauer, Tom Horton, Martin Bidartondo, Anna Levin, Bruns and Taylor Lab,

Dennis Desjardin and the Harry D. Thiers Herbarium.Funding was provided by Novartis

The Western North America Boletus edulis complexThere are six species in Boletus section Edules in Western North America. With the exception of Boletus edulis, the five other species are endemic to this region. One species, the Spring fruiter, appears to be unnamed. Western North America has a high abundance of coniferous forests and these species are all associated with some of the different dominant trees found these forests. Boletus barrowsii and B. mottiae can also be associated stricktly with hardwood trees. Except for B. edulis and B. fibrillosus, these species have adapted to different niches in Western North America.Boletus edulis and B. fibrillosus occur along the coast and in higher montane regions. In both of these habitats they can be found sympatrically fruiting in late summer through the Fall. Although B. fibrillosus appears to be less common and more limited in distribution than B. edulis. Boletus barrowsii is mostly a southwest species fruiting in August and September with oaks and ponderosa pine. Gastroboletus subalpinus (soon to be placed in the genus Boletus) has a similar phenology, fruiting in summer and early fall. This species has a distinctive fruitbody which is contorted with the pores not aligned perpendicular to the ground, preventing easy air dispersal of spores. Gastroboletus subalpinus is limited to the Sierra Nevada and Cascade mountains. Boletus mottiae has long been missidentified as the European species B. aereus. This species fruits later in the Fall well after the rains have come. It occur in the coast range, but not on the coast like B. edulis, and in the foothills (not the high elevations) of the Sierra Nevada and Cascades. The remaining Boletus species, the Spring King, fruits in the spring and occurs in the Sierra Nevada and Cascade mountains. Although the knowledge of the distribution of these endemic species still needs much work, the Sierra Nevada mountains appears to be the center of diversity were there may have been a refugium durring the last major glacial period. Possibly some of these species are migrating Northward since the late Pleistocene.

Department ofPlant and Microbial Biology

University of California, Berkeleycamachof@nature.berkeley.edu

The climate of Western North Americais characterized by dry summers. These dry summer conditions place adaptive pressures on mushrooms which can quickly lose water, shrivel up and thus not produce spores and offspring. Boletus fibrillosus, B. mottiae, Gastroboletus subalpinus, and the Spring King probably evolved in this region. They appear to have develped different adaptations to dealing with summer drought. Boletus fibrillosus which most closely resembles the potential ancestral adaptations of B. edulis occurs in moist habitats in higher montane areas and near the moist fog-influenced coast. In these areas temperatures are not high and evaporative water loss from mushrooms is less. The closestrelative of B. fibrillosus is the Spring King which fruits in the spring when temperatures are cooler and there is plenty of soil moisture from snow melt. Boletus mottiae occurs in drier habitats but it fruits later in the Fall when there is pleanty of rain and more humidity to avoid dessication. It's closest relative is G. subalpinus which does fruit in the summer in dry habitats, but it fruits underground where it is protected from evaporation. These four mushroom species have each evolved unique ways of dealing with the environment they live in.

CI = 0.897Parsimony- informative characters = 174