Humpback brittlegill?

Description:

Growing directly underneath coniferous tree (see last 2 photos). Gills fairly brittle no distictive smell or taste that I can remember. Growing alone with a slightly larger fruit-body about 5-6m away. I have some dried gill fragments and a microscope. Macroscopically two options could be Russula caerulea (Humpback brittlegill) or Russula atropurpurea (Purple brittlegill)