Trichocereus Manguinii aka Trichocereus WK

[Wood Chuck]

This thread of the same name, was posted by Evil Genuis in 2015 and searched, but could not find it. I thought this cactus was a Terscheckii, but was told it was a Trichocereus WK.

She said that it did not grow very tall and that it was like a watermelon inside, since it broke off, I know what she was talking about, as the core is very small. She could tell what it was

by looking at it, yet I do not know these traits and would like to know how to distinguish .