Who is Anna that zeref mentions in the new chapter of fairy tail

" Anna was a Celestial Spirit Mage responsible for opening the Eclipse Gate four hundred years prior to X777, as a part of a plan that was devised by the pacifist Dragons and Anna's clan to defeat Acnologia: send the Dragon Slayers with their foster parents sealed inside them to a period of time that was rich in Ethernano so that their souls, which were maimed by Acnologia's Dragon Slayer Magic, could properly heal. This coincided with Zeref's initial plan to have Natsu become powerful enough to destroy him.[2] " as said on fairy tail wiki. Other than this, I have no idea

Anna Heartfilia
anchestor of lucy
considered as powerful celestial mage
opens eclipse gate