Assuming the below paper is still the accepted phylogeny, it looks like Virginia and Haldea aren’t next to each other on the tree anyway, there’s several other species more closely related to V. valeriae than H. striatula. So never mind the tribe idea. But I guess Thamnophiini would at least narrow it down to fewer species than Natricinae.
https://carstenslab.osu.edu/Publication_files/McVay+Carstens.2013.pdf