But @Pierre, there are other observable differences like the sculpturation of the tegulum and the curvature of the embolus, to which I would give equal weight to the median apophysis if not more, especially when occurring together (and together with traits like tibia shape etc.). The differences in the median apophysis are not very large - only the length of the two tips, and this is perspective dependent. Unfortunately, not well visible on Your lateral photo of atrica. On my keyserlingi photos, the retrolateral position seems to roughly show the same spine as Wiehle's prolateral - long and thin. This seems to be nowhere on atrica' s images. And the rest of the characters fits well Walter' s photos which are of unfortunate positions and do not show the proper length of the long spine of the MA (taken too frontal?)