Anguis is one of the five Unions the player can join in Unchained X. The animal representing the Union is a cobra.
The Anguis Foreteller is Invi, a woman who wears blue and gold robes, with a white hood and a cobra mask hiding her face. Her Keyblade is silver and blue, with a plant motif.
Incidentally, "Anguis" does not refer to a genus of snake, but rather a genus of legless lizards native to Eurasia. Male Anguis lizards have bright blue spots, and juveniles have golden coloring, both of which are present in Invi's motif.
Invi, Ira, and Ava all have gold borders on their robes and hoods.
Invi's name derives from the Latin word "Invidia", which means to represent the sin of envy.