Chemical elements. Thorium, selenium, hydrogenium, oxygenium and so on. That would be 118 rangers or more, if you're including isotopes....
EDIT:
the physics arXiv blog Blog Archive First superheavy element found in nature would mean that we have something like a super ranger as well.
Meteorology. A nimbus ranger, a cirrus ranger, a thunder ranger, a sky ranger, and so on.