Just how wide is its distribution?

The new species is primarily restricted to the southwestern Pacific Ocean (Fig. 3)  with confirmed records from Halmahera and West Papua, Indonesia, northeastern Papua New Guinea (including  New  Britain,  Admiralty  Islands,  and  Milne  Bay  Province),  Solomon  Islands,  Vanuatu,  New  Caledonia,  and Australia. Australian localities include the entire extent of the Great Barrier Reef. The habitat consists of rocky substrates,  frequently  close  to  shore,  often  in  gullies  just  below  the  surge  zone  at  depths  of  about  1–6  m.  It generally occurs solitarily or in small, loose groups.

Don’t ask us how a tropical reef fish that occurs in shallow waters over such an expansive range was not described until 2015.

Chrysiptera caesifrons is described in the latest publication of The Journal of the Ocean Science Foundation (by the usual suspects, Gerald R. Allen, Mark V. Erdmann, and Eka M. Kurniasih).  C.caesiforns is most closely related to Chrysiptera rex, which live in more western Indo-Pacific waters with some cross-over territory around Raja Ampat (Indonesia).

A juvenile C.caesifrons