Maybe, one of our rabid Delias enthusiasts can give us some background about this particular species. I love seeing pictures of wonderful stuff other collectors delve into but, without any kind of information these are just another colorful Delias species. I like it but, for me the species Delias bagoe from New Ireland is tops. Secondly, it would have to be Delias salvini of East New Britain. Delias mayrhoferi is a staggeringly gorgeous black/red item also from East New Britain ( I believe) which soundly rounds out my 3 favorite Delias (over all others). I don't happen to have any of them but, Nomad has kindly posted some exquisite specimens (in the past) from his private collection!
Delias messalina is a rare species that is found in remote mountains in New Britain, New Ireland, Bougainville and Guadalcanal. It usually flies at high elevation on ridges that are thickly covered in dense forest. All of its localities are very hard to access and need considerable, effort, time and money to reach them. The journeys to reach the localities can be quite hazardous and once there the landowners are formidable and will sometimes refuse permission to climb the mountains.
There will almost certainly be at least one unsubscribed subspecies on Choiseul because of the high mountains which are found there. All the subspecies occurring on the islands are easily distinguishable and with their beauty, this make them very collectible.
If I haven't mixed up the columns and rows while typing, I am seeing:
Col. 1: D. m. orientalis (female) Col. 2: same (male) Col. 3: m. lizzae (male) Col. 4: #1-2: m. vigasa (male); #3-5 same (female); #6 m. lizzae (male) #7-8: same (female) Col. 5: #1-6: m. gerrittsi (male); #7-8: m. messalina (female) Col. 6: #1-3: m. vigasa (male); #4-8: m. messalina (male) Col. 7: m. gerrittsi (#1-4 and #7: female; others male)
It's possible that I may have some gerrittsi/lizzae mismarked if the series are mixed...some are difficult to decide based on the amount of red on the verso HW.
Offhand I don't remember the details (it's been a couple of years since I heard about it) - I think it was discovered by Japanese collector(s), and has been determined to be the same as the New Britain ssp (vigasa).
As an aside (and I don't think I've ever seen a comment regarding this), it's unfortunate that "gerrittsi" is actually a misspelling. The taxon is named for Fred Gerrits (one "t"), but he and everyone else are now stuck with a misspelt honorific.