Heiko states this (regarding the Kullander discus species classified in 2006):
What I'm looking for is the name of the publication and if anyone knows if it's available.But there work consisted of some unclaer and overlooked (or misinformed) data and it was revised by
Bleher, Sölting, Salzburger & Meyer, 2007 and is now available. It is a 48-page large publication full of colour photographs, maps and tells the entire history and the updated data (distribution, DNA value, closest relatives, etc., etc.) of the 3 (three) good species, as mentioned here under 2.