What is "megacollybia"

Megacollybia is a genus of fungus in the Marasmiaceae family. Previously thought to be monotypic, the genus was split into several species on the basis of genetic data in 2007 . The type species, M. platyphylla, is restricted in distribution to Europe, Scandinavia, and western and central Russia. M. rimosa was described as new to science from Brazil in 2013.