Yep, Boa Constrictor Amarali are the 'short tailed boas'
They are red-tails, but they tend to be on the short but girthy side of things.
The ones I am looking at are known as 'South Brazilian Amarali' and they tend toward about 5ft for males, 6ft for females. Their markings are more like BCC with bright reds and light background coloring. There are other Amarali locality boas, so Amarali are not all alike, other than all being short tails.
That's what my research has given me - someone please correct me if I am mistaken on any of that.

Here is a link to Barry Miller's page on the species:
http://www.millerreptiles.com/Southb...ns/Sobraz.html