Subspecies are uncommon and rare variations of mobs.
These are currently not implemented, nor known to be planned, and are simply hearsay from other fans ideas.
Uncommon subspecies names
Ashen, Azure, Crimson, Dark, Keppel, Light, Russet, Scarlet, Verdant, Violet.
Rare Subspecies names
Celestial, Ebon, Lunar, Umber
Rare Subspecies for mobs
Celestial: The Mountain Prince
Lunar: The Shade Prince
Umber: The King
Rare subspecies abilities
The Celestial Mountain Prince: Charges into mob/player, breaks blocks when charging
Ebon Cephadrome: Has a chance to spawn in a Cephadrome
The Lunar Shade Prince: Heals it when it's in a wall
The Umber King: Turns nearby blocks into lava, uses abilities if not fighting