Asterism as in all groups is arbitrary in exact form, being a bird-of-paradise, whose compact head (Beta, Gamma, Delta) is between the pole and Triangulum Australe.
Apus (Wikipedia)Apus is a small constellation in the southern sky. It represents a bird-of-paradise, and its name means “without feet” in Greek because the bird-of-paradise was once wrongly believed to lack feet. First depicted on a celestial globe by Petrus Plancius in 1598, it was charted on a star atlas by Johann Bayer in his 1603 Uranometria. The French explorer and astronomer Nicolas Louis de Lacaille charted and gave the brighter stars their Bayer designations in 1756.