G. valesiacum is a laccate species very similar to G. lucidum, although the former has a rudimental stipe, frequent cracks on the crust and paler context (Bernicchia et Gorjón, 2020). Different ecology is also discriminant as decribed below. Despite G. valesiacum is currently an accepted species by both Mycobank and Index Fungorum, it has been proposed that it belongs to a comprehensive complex also including G. carnosum, G. tsugae and G. oregonense and still now not elucidated by molecular phylogeny (Moncalvo et al., 1995; Hong et al., 2004; Lloyd et al., 2018). Nevertheless, recent data by Cusumano et al. (2023) suggest metabolomics can be striking to discriminate G. valesiacum from close species.

Ganoderma valesiacum is considered rare and documented by very few records and poor literature. Basidiomata production appears irregular by time (not every year) and profiles in petri plate report very low growth rate compared to other polypores and Ganoderma species: all this suggests an intrinsic species-specific limit to population growth.
This species grows on Larix only; since L. decidua is native only to the Alpic system and small scattered relict nuclei in central-eastern Europe, G. valesiacum distribution is to be furtherly investigated and records from extra-Alpic areas should be carefully evaluated with respect to close Ganoderma species.
Based on above, G. valesiacum may be native to the Alpic system, possibly an endemic entity, and a peculiar genetic resource to explain radiation dynamics of genus Ganoderma in holarctic kingdom.
In summary, G. valesiacum should be considered for assessment because it is a peculiar, possibly Alp-endemic genetic resource but its population is numerically and spatially restricted.

This species is presumably Alpic.

According to Bernicchia et Gorjón (2020), “G. valesiacum exclusively grows on living trunks or stumps of old Larix. The species grows where Larix is present, frequent only in some valleys of Alps and Dolomites. In Mediterranean area recorded from Portugal, France and Italy”, whereas according to Ryvarden et Melo (2014) this is a “Central European species following natural stands of Larix in higher altitudes in eastern France to the eastern Russia”. However, it should be noted that according to Wagner et al. (2015), that’s the official reference for the JRC European Atlas of Forest Tree Species (2016), L. decidua (the typical Alpic larch) is native only to the Alpic system and small scattered relict nuclei in central-eastern Europe, whereas it has been introduced elsewhere and is often replaced in forestry by L. sibirica (Eurasian), L. kaempferi (Asian) as well as hybrids.
Therefore, G. valesiacum records from extra-Alpic areas should be carefully evaluated with respect to close Ganoderma species.

GBIF (https://www.gbif.org/species/2549723) reports a cumulative amount (1919-2023) of 123 G. valesiacum records all over the Eurasia and whose 74% is placed in the Alpic system. As concerns Italy, verified individuals are to now <10 distributed as follows: 1 from Western Alps; 5 from Central Alps; 2 from Eastern Alps (source: University of Pavia and University of Perugia) and recorded along the last decade (2013-2023). Each individual usually produces 1-3 basidiomata per year, not every year in some individuals.
No specific literature was retrieved about population dynamics and small numbers hamper significant statistic considerations; negative trend is notwithstanding suggested based on data from the Swiss National Fungi Databank, Biodiversitätsdatenbank Salzburg and Österreichische Mykologische Gesellschaft - Austrian Mycological Society. Decline is supposed to be due to change in micro-climatic conditions in larch standings in the subalpine belt. Based on our field observations, habitat degradation may moreover decrease the population fitness in a long-term perspective. Degraded habitats should therefore be considered for careful evaluation and census updating.

This is a basically saprotrophic wood-decay species at the collar or proximal root trait of larch stumps, although it can be also found on still living hosts. According to Bernicchia et Gorjón (2020), G. valesiacum exclusively grows on old Larix. Stumps produced by humans (intentional cut of the host) seem to be the favourite substrates for the Italian samples.
Italian records are referred to: pure L. decidua stands (Central Alps); mixed forests including Picea abies and/or Pinus cembra (Western Alps); mixed degraded forest where P. abies is prevailing and most L. decidua were cut off (Eastern Alps).
G. valesiacum is therefore related to the “Alpine Larix decidua and/or Pinus cembra forests” [9420 according to the 92/43/CEE classification], that is both 42.31 - Eastern Alpine siliceous larch and arolla forests and 42.32 - Eastern Alpine calcicolous larch and arolla forests categories in Corine Biotopes. Noteworthy, the fungus was also found to produce basidiomata in areas which are currently poor in living larches and that are unlikely to support the population in a long-term perspective. That’s the situation of Val di Fiemme and Vipiteno, where larches have been replaced by spruces and suffer for both the competition and human impact.

No specific threats are known to now.
This species produces few basidiomata (1-3 per individual) per year, not every year in some individuals: harvesting should be therefore avoided. Since G. valesiacum is very close to the medicinal species G. lucidum but usually produces larger basidiomata, it may be used to (intentionally or unintentionally) “adulterate” G. lucidum harvest and products, that is, the two species may be mixed to increase the yield. This may furtherly reduce G. valesiacum population.
Changes in local climate conditions and unusual or extreme weather phenomena (e.g. prolonged drought) are likely to affect the population dynamics and basidiomata production.
The habitat [9420] Alpine Larix decidua and/or Pinus cembra forests is classified by:
Favourable Conservation Status in Italy (Angelini et al., 2016). Criticity and impacts: “inappropriate management and use of forests and plantations. tourist and ski facilities, avalanches, temperature change (e.g. increase in temperatures/extremes), changes in biotic conditions (invasive species, e.g. Epilobium angustifolium, Rubus idaeus). Grazing activities: grazing may be appropriate for the maintenance of larch extensive whereas it should be avoided to favor Pinus cembra (where continental climate conditions allow it). In any case, grazing affects the composition of the grass layer and the best situations for this habitat are those without pasture (except that of wild ungulates).

It should be highlighted that this fungus was also found to produce basidiomata in areas which are currently poor in living larches and that are unlikely to support the population in a long-term perspective. That’s the situation of Val di Fiemme and Vipiteno, where larches have been replaced by spruces and suffer for both the competition and human impact.

1)Avoid harvesting (e.g. for medicinal purpose) and damage (especially by tourists)
2) Leave Larix stumps undisturbed whenever possible
3) Since this species is basically saprotrophic and not invasive, reintroduction may be evaluated by means of certified strains from culture collections.

 

The very few data about this species suggest several research topics should be addressed. See above for a detailed description of taxonomy and biogeography issues. Ecological variables (also including wheather and climate) affecting the spreading success and driving the population growth are still unknown.

No traditional usage has been retrieved in Alps. Notwithstanding, this species is currently under examination for the possible presence of bioactive molecules, as other laccate Ganoderma species. References to extra-Alpic specimens should be verified due to possible synonimization with the well-known medicinal mushroom G. lucidum or other laccate species in G. lucidum complex (Teplyakova et al., 2012, Zmitrovich et al., 2006).