ATF leak, and by that 2nd picture, I would place a solid bet on the selector shaft seal. It's not a super hard repair, but it is easier if you drop your valve body (which isn't nearly as hard as it sounds, I promise). It also gives you the chance to replace your pan with the deep version with a drain plug. My personal rule is I never re-install the OEM transmission pan.
But that's just my educated guess. The sure-fire strategy is to clean it all up, and then stuff paper towels in & around anything that could leak and wait to see what turns red/brown. Nothing says it can't be multiple leaks.