My tongue is cracked but also a little whitish due to the yeast overgrowth (even though I'm on antifungals). I think it's always been like that but I barely remember what I had for breakfast yesterday so my memory can't be trusted!
I vaguely remember reading something about
a fissured tongue—I can't find it now —this isn't what I'm thinking of but it is interesting (I wish I had a Chinese medicine man in my life!):
www.rdhmag.com/articles/print/volume-31/issue-5/columns/the-tongue-a-window-to-other-organs.html-p