Limited geographical and host range, in addition to threats from predicted climate-mediated habitat shifts, are factors supporting Global Red List Assessment for this species. However, the difficulty of field identification of this species and the circumpolar occurrence of the morphologically similar Laccaria montana place an additional burden on defining the geographical range of L. pseudomontana. Therefore, the species should currently be classified as Data Deficient (DD) until further research has been conducted.
As a small, reddish-brown to orange-brown Laccaria species, L. pseudomontana could be misidentified as L. montana, L. pumila, or a small form of L. laccata. Based on DNA sequence data and observation of basidiospore morphology using light microscopy and scanning electron microscopy, L. pseudomontana is distinguishable from these other taxa in having more ellipsoid spores with less prominent echinulae, by DNA (ribosomal ITS) sequences, by the number of spores produced on each basidium (which distinguishes L. pumila from these other species), and often—but not always—by macromorphological characteristics, specifically smaller size and more darkly colored, red-brown basidiomata (Osmundson et al. 2005). Subsequent extensive DNA sequencing of North American Laccaria collections further supports L. pseudomontana as a genetically distinct, geographically limited taxon (G.M. Mueller, personal communication). Additional examination of alpine and high subalpine (elevation > 3000 m) collections identified as L. montana recovered two collections likely to be L. pseudomontana (Osmundson et al. 2005), suggesting the need for additional examination of herbarium material.
Laccaria pseudomontana is currently known from only three high-altitude alpine sites in the Rocky Mountains (Tenmile and San Juan ranges, Colorado); examination of herbarium collections suggests that the species may also occur in the Colorado Front Range. Extensive collection of Laccaria in similar habitats in Colorado, Montana, and Wyoming has not resulted in additional collections of this taxon. The species appears to be limited to high-altitude (elevation > 3300 m) sites, where it forms ectomycorrhizal symbiotic associations with willow (Salix) shrubs.
Arctic-alpine ecosystems are particularly vulnerable to effects of climate change, including upward elevational shifts in treeline and climatic conditions that exceed the narrow environmental tolerance of some species (Ellis & Yahr 2011; SCBD 2009). Alpine habitats are discontiguous; therefore, species with limited dispersal capacity and/or small numbers of reproductive individuals may be particularly threatened.
While many fungi described from the Rocky Mountain alpine zone are more widely distributed—in some cases circumpolar—arctic-alpine species (Cripps & Horak 2008), L. pseudomontana appears to be a southern Rocky Mountain alpine endemic based on current data.
This species has been collected from three locations in the Tenmile and San Juan mountains of Colorado, USA. Examination of herbarium collections of L. montana suggests that L. pseudomontana also occurs in the Front Range (Osmundson et al., 2005). Subsequent DNA sequencing and phylogenetic analyses involving extensive sampling of North American Laccaria support L. pseudomontana as phylogenetically distinct and have not uncovered additional geographical occurrences (G.M. Mueller, personal communication). Extensive collection of Laccaria on the Beartooth Plateau (Montana and Wyoming) over the past 15 years has not located L. pseudomontana, suggesting that the species does not occur there; it is therefore possible that L. pseudomontana is a southern Rocky Mountain alpine endemic taxon.
Currently, L. pseudomontana is known to consist of three subpopulations, and an additional two subpopulations appear to be present based on examination of herbarium material. A small number of basidiomata from each of the five known or suspected subpopulations has been found, likely representing a single functional individual from each population. Because Laccaria species often produce basidiomata prolifically where present, they are likely to be associated with a higher probability of detection than are many other ectomycorrhizal mushroom-producing basidiomycete fungi; therefore, a multiplication factor of 10 undetected functional individuals per site was selected as a rather conservative estimate, with an additional multiplier of 2 mature individuals per functional individual (Dahlberg & Mueller 2010). Targeted collection of alpine fungi by professional mycologists has occurred in many of the accessible alpine habitat sites in the Colorado Rockies; therefore, an additional multiplier of 10 undetected subpopulations per known or suspected subpopulation was selected as a reasonable estimate. The multiplication of 5 known subpopulations x 10 functional individuals x 2 mature individuals x 10 unknown subpopulations results in a current population size estimate of 1000 individuals. However, the considerable potential for misidentification of this species and the possibility that the species may occur in other arctic-alpine regions, and/or may extend into the upper subalpine zone in Colorado (Osmundson et al. 2005), adds considerable uncertainty to this estimate. If further research supports the current hypothesis of this species as a restricted, southern Rocky Mountain alpine endemic, the estimated population size would correspond to a designation of Endangered (EN) under IUCN criterion C2a(i).
Population Trend: Uncertain
Like other Laccaria species, L. pseudomontana appears to form ectomycorrhizal symbioses with the roots of woody plant species. Laccaria pseudomontana has been found exclusively in association with shrubby Salix species including S. glauca and S. planifolia. It has been collected in alpine habitats in Colorado at elevations of 3300-3700 meters. Extensive collection of Laccaria associated with Salix shrubs in similar habitats on the Beartooth Plateau, Montana/Wyoming, has not resulted in additional collections of L. pseudomontana.
Arctic-alpine ecosystems are particularly vulnerable to effects of climate change, including upward elevational shifts in treeline and climatic conditions that exceed the narrow environmental tolerance of some species (Ellis & Yahr 2011; SCBD 2009). Rocky Mountain alpine habitats are discontiguous; therefore, species with limited dispersal capacity and/or small numbers of reproductive individuals may be particularly threatened.
Laccaria pseudomontana is macomorphologically similar to L. montana and can be mistaken for that species, which appears to be much more widespread. Although extensive collection has not recovered additional field specimens of this taxon, examination of herbarium specimens of L. montana suggests that at least some L. montana specimens from the Colorado Front Range belong to L. pseudomontana. As L. montana is reported from arctic-alpine habitats in Canada and Europe, closer examination of herbarium material from those regions should be undertaken to better understand the geographical distribution of L. pseudomontana by determining whether any of these collections are referable to L. pseudomontana.
Cripps, C.L. and E. Horak. 2008. Checklist and ecology of the Agaricales, Russulales, and Boletales in the alpine zone of the Rocky Mountains (Colorado, Montana, Wyoming) at 3000-4000 m a.s.l. Sommerfeltia 31: 101-123.
Dahlberg A. and G.M. Mueller. 2010. Applying IUCN red-listing criteria for assessing and reporting on the conservation status of fungal species. Fungal Ecology 4: 147-162.
Ellis, C.J. and R. Yahr. 2011. An interdisciplinary review of climate change trends and uncertainties: lichen biodiversity, arctic-alpine ecosystems and habitat loss. pp. 457-489 in: Hodkinson, T.R., M.B. Jones, S. Waldren, and J.A.N. Parnell, eds. Climate Change, Ecology and Systematics. Cambridge, UK: Cambridge University Press.
Osmundson, T.W., C.L. Cripps, and G.M. Mueller. 2005. Morphological and molecular systematics of Rocky Mountain alpine Laccaria. Mycologia 97(5): 949–972.
Secretariat of the Convention on Biological Diversity (SCBD). 2009. Connecting biodiversity and climate change mitigation and adaptation: Key messages from the Report of the Second Ad Hoc Technical Expert Group on biodiversity and climate change. Secretariat of the Convention on Biological Diversity, Montreal. Technical Series No. 41.