This is the tip of the round wing Pitts.   

If you look at the end of the front spar you can see the taper required to blend the thicker portion of the wing to the wing tip.  On the top and bottom of this tapered spar are gluing strips, the same that are placed between the spars where the wings leading edge cover is attached.   At this time, the leading edge cover is permanently attached to the wing.

In between the two ribs, in front of the spar, is a short little rib.  This is called a nose rib.  Under the Leading Edge Cover between each wing rib there is also a short little nose rib.

One of the advantages of building a square wing is that the end ribs and the end nose ribs are the same size as the rest of the ribs and don't require a separate jig to complete the wing.  Constructing these jigs take a lot of time and the round wing Pitts requires the building of extra jigs just for these two smaller end ribs.

As I mentioned before, Sean Tuckers Airplane has square wings. I believe he knows a little more about this stuff than me so if I were to build a Pitts, I would probably use the design the pro's are using.