How to distinguish Epacromius tergestinus from Epacromius coerulipes?
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As I have no experience with Grasshoppers, I cannot help you. That said I rely upon asking Identifiers these types of questions within Observations and have found that to be an effective way to get answers to extremely knowledge-base specific questions like this.
RG Observations of E. tergestinus
RG Observations of E. coerulipes
Otherwise you might wish to try looking for keys for each species.
I use https://orthoptera.speciesfile.org/ quite often. and it leads to an ebook, https://www.biodiversitylibrary.org/item/224097#page/219/mode/1up Page 207.
These grasshoppers look quite similar to Aiolopus thalassinus and related Aiolopus species. There could be other articles which have the key to species.