Yes, davisi and auriferus are close!
However, these "harnedi & -like" cicadas from sw TN, n. MS and nw. AL are more like auriferus in wing shape and other traits than are pop's of the nominate race, davisi. The taxonomic placement for these remains in debate and will likely require genetic analysis to tease apart the details...as you observed, auriferus and davisi are very similar and for the record very closely related.

It's also important to mention that the color schemes you mentioned as differentiating the 2 are not absolutes for either (compare pic's). Both auriferus and davisi vary in size, color and pattern across their ranges. Both species may be orangish-brown, rust, bright green, dark green, yellow green, olive, taupe, tan, even black!...or combo's of these colors...etc.

Side note, although resonans and auletes are similar, they are quite different in wing shape (like davisi nominate from auriferus & harnedi). The wings of resonans are narrow by comparison and the thoracic patterns are slightly different between these two big cicadas. As I recall from previous discussions with a few cicada folks, resonans is actually closer to resh in several ways than it is to auletes.