R-L categories correct, but text here does not match final assessment. Updated version will be published in IUCN´s Red List June or Nov 2019.
Cortinarius splendificus is a mainly Mediterranean species, associated with calcareous Quercus ilex forests (a few northern outposts in calcareous Carpinus-Quercus forests) (Schmidt-Stohn et al. 2016), a forest type with many habitat-specific taxa of Cortinarius, subgenus Phlegmacium.
The Quercus ilex forests and woodlands have been declining e.g. due to transformation into secondary macchia due to land-use, severe forest fires, and die-back of oak due to Phytophtora and other pathogens.
Global red-list assessment: The species is estimated to have a total population of 8 000 IUCN-individuals. According to the C criterion (C2 a(i)), the species then becomes red-listed as VU, based on a continuous decline, population size <10 000 individuals and very small/isolated subpopulations.
Cortinarius splendificus is a striking, rare species, which has its major distribution in the Mediterranean region from Spain to Italy (Schmidt-Stohn et al. 2016). The species are recorded from more districts in Spain, from Languedoc in S France and from both the eastern and western side of the Apennines in C Italy. Probably the species occurs also further eastward in the Mediterranean region (these areas are little investigated mycologically). Outside the Mediterranean climate zone(s), the species are recorded a couple of times in southern temperate sites in France and in Germany.
The species is known from approx.. 10 sites/localities in Spain, approx. 5 sites/localitites in Languedoc in SW France, two sites/localities in the Apennines, C Italy, as well as three localities outside the Mediterranean region (France, Germany). Altogether approx 20 sites/localities are verified/published (see Schmidt-Stohn et al. 2016). The real, total number of sites/localities of C. splendificus are here estimated to 400.
This is equivalent to 8 000 individuals according to IUCN standards.
The decline of the calcareous Quercus ilex forests in the evaluation period (last 50 years) is estimated to be in the magnitude of 15-20%. Based on this, the species becomes red-listed as NT according to the A-criterion (A2c + 3c + 4c) (species/habitat decline >15%). According to the C criterion (C2 a(i)), the species becomes red-listed as VU, based on a continuous decline, population size <10 000 individuals and very small/isolated subpopulations.
Population Trend: Decreasing
Cortinarius splendificus is associated mainly with Mediterranean sclerophyllous Quercus forests, chiefly calcareous Q. ilex forests. Some southern temperate outposts are found in xerothermous Quercus pubescens woodland, as well as in Carpinus-Quercus stands (Schmidt-Stohn et al. 2016).
Cortinarius splendificus and its habitats (calcareous Quercus ilex forests) have been declining e.g. due to transformation into secondary macchia due to land-use, severe forest fires, and die-back of oak due to Phytophtora and other pathogens.
To prevent decline and further fragmentation of calcareous Quercus ilex forests with good habitat quality, it is important to set aside reserves on calcareous hotspots, housing many rare/redlisted, habitat-specific species such as C. aurilicis, C. quercilicis, C. humolens. It is furthermore important to establish also sites with a less strict conservation regime, such as woodland key biotopes, where some non-destructive human activities are accepted (such as non-intensive, closed cutting).
More mapping/surveying and monitoring of C. splendificus are needed. More data on occurrences in calcareous Quercus ilex forests of the W Mediterranean region (core region) are needed, but also data from the almost un-explored eastern Mediterranean regions. Finally, more documentation on the degree of decline of the habit itself is needed.
Schmidt-Stohn, G., Saar, G., Brandrud, T.E. & Dima, B. 2016. Interessante Phlegmacium-Funde um Urbino. J. Journées Européennes Cortinaire 18: -.