Are there any confirmed cases of melanism in snow leopards? I am aware that melanism is much more common in Jaguars and Leopards, both often called black panthers, but I cannot seem to find any info on melanism in snow leopards.
I'm not aware of any confirmed cases of melanism in snow leopards either.
There are some relevant studies on the evolution of melanism on Felidae. Melanism seems to occur only in two extant species of the genus Panthera (Panthera onca and Panthera pardus). There is a direct correlation between melanistic colorations and enviroment (especially humidity):
Moist forests (especially in Southeast Asia) presented very high frequencies of melanistic leopards (e.g., 39 of 71 individuals [55%] in Southeast Asia), and more than 80% of the black animals in our database, a fivefold increase relative to the expected number based on the overall number of records. Furthermore, we found no confirmed melanistic leopards in the Middle East, Arabian Peninsula, Central China, and Russian Far East, nor any mention in the literature as to the presence of melanism in these regions, indicating that this polymorphism is really absent from these areas. Overall, there was a significant reduction in the frequency of melanism in some biomes that consist of open habitats or temperate forests. There thus is a clear pattern in which melanism tends to increase in tropical/subtropical moist forests and decrease in open/dry or temperate habitats