Echinodontium ballouii wasn't seen for 100 years until Larry Millman found it in an Atlantic White Cedar swamp. Larry took me to the site, (which I can't say where it is) and we found about a dozen of these again 4 years after the first visit.
06 Oct 2017.
Buckingham Springs, Bucks Co, PA.
Female.
Found on Rosa multiflora.