I'm working on the fauna of Syria in the Middle East, so maybe I need keys like that of Amnon which is not available in an electronic copy, or I need an holistic key.
I'll use the key from you while I can get a suitable one.
You can see https://www.researchgate.net/publication/228772134_A_Revision_of_the_quadratula_Group_of_the_Genus_Terellia_Robineau-Desvoidy_%28Diptera_Tephritidae%29
Article A Revision of the quadratula Group of the Genus Terellia Rob...
1. Fruit Flies (Tephritidae): Phylogeny and Evolution of Behavior, Edited By: Matin Aluja and Allen Norrbom, 944 pages.
2. Insecta Helvetica, Fauna Band 10: Diptera: Tephritidae, Bernhard Merz Author, 198 pages - is on sale quite cheap on NHBS.
3. Keys to the Tropical Fruit Flies of South-East Asia (Tephritidae: Dacinae), Richard AI Drew (Author), Meredith C Romig (Author), 250 pages, illustrations.
The best database to help you on the tephritidae is here:
De Meyer, M. & I.M. White. 2004. True fruit flies (Diptera, Tephritidae) of Africa. A queryable website on taxon and specimen information for afrotropical Dacine fruit flies. http://projects.bebif.be/enbi/fruitfly/ - Tervuren: Royal Museum for Central Africa