The specimen doesn't match Hobgoblin or Harpy signatures either.
Defeat a Minotaur, Wyvern, Cyclops, and Hydra to identify a final match.
Minotaurs, Wyverns, Cyclops, and Hydras are Vex combatants that can be found on Nessus.
"The Guardian's going toe-to-toe with some of the biggest, baddest Vex out there! Kick their butts, Captain." —Failsafe