There are 6 in total, 1 for each area of the dlc. You need to stand in front of each statue and press x for it to count.
1) in hyperion dump, against the wall to the left as you enter.
2) in sanders gorge it's right at the start of the main path, pretty hard to miss.
3) in dividing faults, its right at the beginning in front of you to your right as you enter and go down the stairs
4) in scorched snake canyon, it's in a corner to your left as soon as you walk in.
5) in tartarus station, on the winding path that leads to wayward pass.
6) In Wayward Pass, along the path on the right as you exit the arena with Knoxx-trap