Looks like the new "boss" pets are on the PTR! Thought I'd make a thread showing what I've found so far. If you have anything to add, please do!
As shown in the pictures, the fabled pets have yellow paw prints above their heads instead of green, so they're pretty easy to spot.

You can currently fight them without being on the quest (though this may change). They seem to have normal pet moves, but are much stronger. Pets don't copy to the PTR at the moment so I couldn't properly test the battles.

Now for the pets themselves!
Jade Forest:
Nitun

Map Location:[url]http://img23.imageshack.us/img23/861/nitunmap.png[/url]
Ka'Wai (Credit to Petopia for the pic)

Map Location: N/A
Valley of the Four Winds:
Greyhoof

Map Location:[url]http://img7.imageshack.us/img7/9086/greymap.png[/url]
Kun-Lai Summit:
Kafi

Map Location:[url]http://img823.imageshack.us/img823/8313/kafimap.png[/url]
Dos-Ryga

Map Location: [url]http://img708.imageshack.us/img708/9324/dosrygamap.png[/url]
Townlong Steppes:
Ti'un the Wanderer

Map Location: [url]http://img195.imageshack.us/img195/4547/tiunmap.png[/url]
Dread Wastes:
Gorespine

Map Location:N/A
Vale of Eternal Blossoms:
No-No

Map Location: [url]http://img827.imageshack.us/img827/5416/nonomap.png[/url]
Will update the thread as more info arises.