So here is the sitch.
The ranks have changed a couple of times in the past when we have adjusted post-counts. That hasn't happened for many years, but did happen in the early days. Then we moved to the V3 atomic and the archives were pared off. At first, the post-count including the archives posts were included in your count. Then the forum was upgraded a while ago and it re-counted posts (only taking into account V3 posts and nothing in the archives). This reset everyone to only posts that were in V3 and they lost the count from the archives. At one point we then managed to get super Dan to add the counts back in, but then another upgrade happened and we lost them again. Now the archives are unavailable and we haven't managed to get the counts across again.
We are working on this in the background, however I can't yet give you a time-frame for if it will be fixed or even if it CAN be fixed at this stage. I can't even promise that if another upgrade happens you won't be set back to serf. But we will do our best.
The ranks haven't changed in years and years. You start as a serf with 0 posts and work your way up to Colossus at 65536 posts.
The groups are as they have always been (mostly) as well. For anyone who is super curious, here they are (most of them)
Atomican (127+ posts, inactive atomicans)
Atømican (127+ posts, active atomican)
God (mag staff)
Goddess (mag staff)
Guests (not logged in)
Hero (inactive hero)
Herø (active hero)
Lurker (less than 15 posts)
Quark (15 to 126 posts)
Super Hero (inactive Superhero)
Super Herø (active Superhero)
SO... tl;dr version is it's a known bug and we are working on it, but can't promise anything at this point except that your post count should be your V3 post count going forward as far as we know.