Inocybe substellata is an apparently fairly rare (arctic-)alpine ectomycorrhizal species, with a distribution mainly restricted to Northern and Central European mountains. It is association with snowbed habitats, which have been undergoing climate-driven decline in extent and quality through reduced snow cover, drying, and vegetation shifts (see Threats section for references). Further deterioration is predicted with continued biodiversity loss and decline of specialized alpine mycorrhizal fungal communities under future climatic conditions. Based on these observed and projected habitat trends and the species’ ecological specialization, an ongoing and future global population reduction of at least 15% over a 50-year assessment period is conservatively inferred. The species is therefore assessed as Near Threatened (NT) under Criteria A3c+4c.

Inocybe substellata belongs to the nodulose-spored inocybes in the Marginatae group (having a more or less marginated basal bulb). It was described by Kühner in 1988 (initially as I. salicisherbaceae var. substellata), and the name has been used rather consistently since this. In alpine zone it can be confused with look-a-likes such as I. phaeocystidiata, which means that reports without DNA-sequence verification should be taken with some caution.

Inocybe substellata is a more or less strict alpine species with major habitat in snowbeds, a nature type showing a strong decline due to climate change.

Inocybe substellata is well documented from Norwegian-N Swedish-N Finnish mountains, including approx 10 sequence-verified collections. From C Europe, the species is known from the Alps (France-Switzerland-Austria-North Italy), also here with approx 10 certain records. (3 records of e-DNA from a European grassland soil project; from Spain-England Russia, are here not accepted.) eDNA sequence data from the Global Spore Sampling Project (Ovaskainen et al. (2024)), suggest that the species also occurs in Greenland, which likely represents its westernmost distribution area.

Population size: In N Europe, the number of localities is estimated to approx 1000 (600 in Norway), In C Europe; the Alp region, including probable populations also in the Carphatians, we estimate a equivalent number of localities (1000). We assume on average 5 (10) fungal individuals (unique genets) per site each potentially comprising of several clones resulting in a total population size of >20000 mature individuals in Europe (cf. Dahlberg and Mueller, 2011). So far there is no evidence of N American populations.

Trends: Inocybe substellata is easily overlooked, and known records therefore likely represent only a fraction of the true population. It is associated with alpine and arctic-alpine habitats, particularly snowbeds with Salix herbacea and other Salix shrubs, which have been declining and are expected to continue to decline, particularly due to climate-driven vegetation change. Based on these habitat trends and the species’ ecological specialization, an ongoing global population decline of at least 15% over the next 50 years is conservatively inferred.

The species is reported mainly from dwarf Salix snowbeds on calcareous ground, also from Salix shrubs, and from Norway and Finland there is a few records from below timber-line in regularly flooded Salix vegetation along rivers/lake shores.

Inocybe substellata is threatened by climate-driven habitat loss and vegetation change in alpine and arctic-alpine habitats. Snowbeds, where the species and its dwarf-Salix hosts frequently occur, are particularly sensitive to reduced snow cover, drying, and longer growing seasons, with pronounced vegetation change already documented (Sandvik & Odland 2014; Matteodo et al. 2016; Björk & Molau 2007). Increasing dominance of shrubs and graminoids may reduce suitable habitat for low-growing Salix hosts, while predictive studies indicate that specialized alpine mycorrhizal fungal communities are likely to decline under future climatic conditions (Niittynen et al. 2018; Arraiano-Castilho et al. 2024). Alpine zones are naturally restricted habitats, as populations have limited capacity to track suitable conditions and move upwards. Furthermore, although of minor importance but of local significance may be physical disturbance of alpine habitats through construction, e.g. for tourism negatively affect local populations.

Conservation should focus on maintaining the extent, quality, and ecological integrity of known and potential arctic and alpine habitats and preventing avoidable local degradation from infrastructure development, intensive recreation, and other physical disturbance. Although the broader impacts of climate change cannot be addressed through species-specific conservation measures, protecting intact and well-connected alpine habitats may increase the resilience of Inocybe substellata and its host-plant communities to ongoing environmental change.

Inocybe substellata belongs to complex group in the Marginatae, where a number of species can be difficult to separate morphologically (some also in alpine habitats). Targeted surveys in suitable habitats and molecular identification of specimens are therefore needed to clarify the species’ distribution, and the degree of association with threatened habitats.

There is no use and trade known.