Moved to species page.

ID'd with the help of Phillip Harpootlian. Punctate elytral striae exclude G. semiopacus. G. blackburnii and G. splendidus have the sutural striae ending at the scutelum as compared to G. hornii and G. balyi which have their sutural striae bend and wrap around the scutelum (hard to see on this photo but it is there if you look closely). Also, the antennal clubs of hornii and balyi tend to be light brown as opposed to dark brown or black. Hornii differs from balyi in that balyi always has some blue, green, or purple iridescence (albeit subtle in this photo) while hornii is pure anthracite black.