I just checked. The new and unique surface biological sites were crystal shards and amphora plants,
I wasn't referring specifically to surface bio in fact, and I know exactly when crystal shards were found because I found them first, in fact I found them in beta and sat at the planet waiting for the release of chapter 4, landed and scanned one as soon as the game finished updating. Tube Worm things, they call them Sinuous Tubers now, were known about before but not discovered until chapter 4 was released simply because no-one was looking for them was looking in the correct area, the FSS enabled us to find them because we were now able to scan bodies to indentify which ones have bio rarther than flying across the surface looking for POI's.
The fact that new biology was last discovered in space may simply be that every CMDR gets notified if there is space borne bio without having to scan everything, the fact that there have been no knew bio discovered on the surface of bodies may simply be that most CMDRS, as you claim at least, don't scan all the bodies in systems with the FSS and will therefore never know if they have missed anything. If you don't look for it you will never find it!
Even before chapter 4 was released FDEV stated that there were things out there in the galaxy that hadn't been found, good luck with that if those things are a particular surface bio restricted to a particular area in the galaxy.
I'm certainly not that everyone check systems the same way I do, I also don't claim that people are using the FSS incorrectly, basically do what you want, but I do smile when I see threads and posts from CMDRS claiming that all the bio has vanished because they can't find any, oh well.