Assassin bug nimph

I checked BugGuide, and the only similar bug they have is A. cristatus, but it has many differences in details. I thought that it was more similar to some wheel bugs nimphs that there are there. But, as I allways say, I am not a biologist, let alone entomologist. So, most of my guesses are just plain wrong... :-(

That is quite a specimen. Definitely an assassin bug nymph. The wheel bug I'm familiar with is A. cristatus, though I'm aware there are other species within that genus in South America. I haven't been able to find any other information on those species, sadly. What makes you think it's a wheel bug nymph? (Out of curiosity!)