Machacuay is the serpent, read from the dust lanes of the Milky Way where they begin to broaden, and it is the first of the Andean dark constellation series to appear. Behind it in the sequence come the toad, the tinamou, the llama with its offspring, and the fox.
The order is the substance. These are not five separate attributions that happen to be in the same part of the sky; they rise in a fixed sequence over the course of the year, and the sequence is what the system is for. A herder or a farmer who knows the order knows the season, and the sequence maps onto planting, the rains, the birthing of the llamas and the harvest.
The serpent's position at the head of the series is not arbitrary either. Andean cosmology puts the snake in ukhu pacha, the world below, against the puma of this world and the condor of the world above, and the first of the animals to come up out of the horizon is the one that belongs underneath.
The dark constellations coexist with ordinary star-to-star constellations in Andean reckoning, including a set built from bright points. Both systems were in use at once, which is worth stating, because the dark ones are unusual enough that they tend to be presented as though they were the whole of Andean astronomy.