In addition to pets coming with the Deadmines Pet Battle Dungeon, the latest 7.2.5 PTR build added two pets that drop from the Time-Lost WalletTime-Lost Wallet inside the Deaths of Chromie Scenario and our friends over at WarcraftPets seem to have discovered a new fairie dragon pet possibly from Argus.
The pet is a miniature version of the Reins of the Bronze Drake mount and has a unique Rewind Time ability
"This particular drake has oddly retained its age throughout its travels, but its size has certainly changed."
The pet's a miniature version of the Reins of the Time-Lost Proto-Drake (Storm Peaks) mount and comes with the an ability to bend time
"The Bronze Proto-Whelps have been discovered only in the most peculiar of timelines."
Sun Darter Hatchling - Faerie Dragon Pet
Quintessence from WarcraftPets suggests this pet may be from Argus as noted by its description. If you try to paste the item in-game (Patch 7.2), it seems to coincide with a mount tagged named as "REUSE", however 7.2.5 Mount Journal lists the pet and so does the in-game tooltip.
Sun Darter Hatchling drops from Oddly-Colored Egg (Source N/A)
"This unique species of faerie dragon is not usually found on Azeroth."