Looking back through my session, I'm having trouble constructing this guy's turn check-raising range.

Villian is 16/10/3.5 AgF of 50% over 63 hands. When I sat down, he was sitting on a ~350 bb stack. He has 3bet one time pre. The hands he's shown down so far was when he stacked off on the flop with a set of deuces that was beat with a higher set. He has also flatted an UTG raise with QJs and checked down unimproved.

He seems decent, but nitty.

He flats my PFR from the SB, then check-calls a PSB on the flop. Then he check-raises the turn.

Is this exactly KQs? I'm thinking QQ 3bets pre. Thoughts on his range?

PokerStars - $0.05 NL (6 max) - Holdem - 5 players
Hand converted by PokerTracker 3

BB: $5.40
Hero (UTG): $5.18
CO: $2.74
BTN: $6.76
SB: $12.45

SB posts SB $0.02, BB posts BB $0.05

Pre Flop: ($0.07) Hero has A K

Hero raises to $0.20, fold, fold, SB calls $0.18, fold

Flop: ($0.45, 2 players) Q K 8
SB checks, Hero bets $0.43, SB calls $0.43

Turn: ($1.31, 2 players) 8
SB checks, Hero bets $0.62, SB raises to $1.70, fold

QK and an occasional 88?

I think this is legitimately a difficult decision, as reflected in your thought process:

"He seems tight and straightforward, I will bet here to protect my hand, and maybe occasionally a worse hand will call, and if he raises I can fold"

"He raised, so I fold, right? Wait a second: his preflop coldcalling range doesn't have many hands in it with 8s in them. The most likely hands for him are 6 combos of KQ, but there are just so many more combos of other hands: Adxd, JT, air. Even if he doesn't bluff- or semibluff-raise with these hands very often, there are so many more of these hands that it's still pretty likely for him to have one"

I don't think either folding or calling is a big mistake here. The fact that we don't really know what to do if he raises suggests that this might be a good turn to check for pot control, even though there are a reasonable number of draws. If it were me I would fold, but be more likely to suspect him of moves in the future.