I have found some specimin growing in rotting wood which I have dried. They have a wonderful maple/ butterscotch aroma and resemble the pictures of the lactarius rubidus. However, I never see New Mexico mentioned with the entries in handbooks or on websites. Has anyone found these candy caps in New Mexico?
I find no mention of L. rubudis in my books (a link here though: http://botit.botany.wisc.edu/toms_fungi/oct2005.html). There is mention of a L. rubrilacteus in "Mushrooms of Colorado". I don't know if this is the same species. I would pay more attention to the characteristics of your specimen and its micro-environment than to a book's description of a species' range. In particular, it depends on where you found it in New Mexico. There is a world of difference between a ponderosa forest in the Gila and a spruce forest in the Sangre de Christos. Can you post photos of your specimen? Can you describe where you found it?