Species
Terscheckii
The heavily armed giant of the group, and the plant whose botanical name has moved furthest from the one the trade still uses.
One plant, three published names
Reportedly, the International Plant Names Index records Trichocereus terscheckii (J.Parm. ex Pfeiff.) Britton & Rose as a validly published name, first published in 1920. The same plant was reportedly published as Echinopsis terscheckii by Friedrich and Rowley in 1974, and again as Leucostele terscheckii by Schlumpberger in 2012. Reportedly, the Caryophyllales Network, the working taxonomy for the cactus family, carries the plant as Leucostele terscheckii, with Trichocereus validus in its synonymy.
Which name to use
A grower will call it Trichocereus terscheckii, and a botanist working to the current treatment will call it Leucostele. Either name gets you the same plant.
Where it grows wild
It is reportedly collected widely in the wild, overwhelmingly in Argentina, with a few plants from Bolivia and Chile.
What growers report
One grower groups it with the other heavy-bodied species as unusually resistant to sun, pests and rot, slow-growing by the standards of the genus, and shy to flower.
A clone name is not proof of a species, and a photograph is a pointer rather than an answer.