[As is noted in Wikipedia, the area where the photo was taken is actually outside of Spidermonkey range. Most of Venezuela is without spidermonkeys]
Despite what Sanderson says, spider monkeys do not have the same limb proportions as the creature in DeLoy's photo. Furthermore, it is readily apparent that the smaller monkeys have eyes of a different structure: "Beady little eyes" as opposed to the larger and more human-like eyes of the DeLoy ape. This is a function of ABSOLUTE size, showing that it actually IS much larger than a spider monkey. Furthermore, its fingers and toes are noticeably much larger and stronger in the creature in the photograph, while the fingers and toes of a spider monkey look almost flimsy in comparison. They also line up and work together rather like the digits in a seal's flippers, in a bundle.
Preserved museum spider monkey hand and skeletal hand
left foot in profile, unaltered original below
Obviously much more developed big toes, and other toes in opposition.
The teeth are fortunately shown and they are orthognathous, with an even bite. And although the structure of the area around the eyes and even the structure of the nose resemble a spider monkey, in fact those features are not EXCLUSIVE to spider monkeys. In fact, Siamangs have features that are very similar also.
A spider monkey's teeth are not orthognathous but jut out to the front. The DeLoy animal does NOT have a spider monkey's teeth. Furthermore, the jaws are very definitely heavier and more rounded.
Spider monkey skull on the left; female siamang on the right. From Bone Clones. It's a pity they are not in closer parallel position for comparison, but it is plain to see that the spider monkey's jaws are like a set of small pinch pliers whereas the siamang's jaws are aligned for a stronger vertical bite.
I am satisfied from what I can see of the teeth in the DeLoy photograph that the teeth are much the same as a siamang's and that combined with the shape of the hands and feet and face make a pretty strong case for a direct relationship as far as I am concerned.
Female Siamang with young
I have said before that I think Mapinguaris are basically orangutans that crossed the Bering straits in prehistoric times. I also think that the ancestors of siamangs went with them. The Ameranthropoides are not identical to the regular siamangs by a long way, but they are similar enough that they could be descended from the same ancestors. And although the creature in the DeLoy photograph is large even by siamang standards, the more usual size might well be closer to three feet tall. Indeed, both Sanderson and Coleman count the "protopygmy" Shirus and DiDis to be usually from three to five feet tall and described in terms such as might describe a siamang. I include a map of similar creatures as reported in South America.
Best Wishes, Dale D.