User blog comment:FairyRaven/Fairy Tail Chapter 426: Black Heart, Review and Commentary/@comment-173.225.247.204-20150402204613/@comment-7418318-20150403143628

For some, probably marketing related, reason the people in charge of the anime decided to call everything from "The Start of a new Adventure" up to the actual Tartarus chapters the Tartarus arc.

So don't expect Jackal to blow the council up tomorrow, since that's still several weeks away. For now we'll have the "Sun Village arc" chapters animated.