I've read some very conflicting information (I believe from the same source, Harri Lorenzi), about the ultimate size attained by some of these myrciaria species.
If I recall, at first he states that M. tenella only attains a maximum height of about 1-5m (in brazilian fruits book), but it turns out it's more like 5-8m in his new book.
And there were other species that had gained a few meters, since his first book.
I believe the second book is probably more accurate (Brazilian Trees Vol 3), but I'm not sure.