400NL - TP no kicker, should I call this river bet ?

[Mat]

Villain is 25/12/1.8 over 200 hands. No history, he's regular but not very good (open-limp a ton, etc...).

Everest Poker No-Limit Hold'em, $2.00/$4.00 (HH Converter by Kreatief)

SB ($62.00)
BB ($405.60)
CO ($546.50)
Button ($590.70)

Preflop: Hero is Button with 8[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/diamond.gif[/img]
CO calls $4.00, <font color="#CC3333">Hero raises to $16.00</font>, <font color="#666666">2 folds</font>, CO calls $12.00,

Flop: A[img]/images/graemlins/spade.gif[/img], 6[img]/images/graemlins/diamond.gif[/img], T[img]/images/graemlins/heart.gif[/img] ( $38 )
CO checks, Hero checks,

Turn: K[img]/images/graemlins/heart.gif[/img] ( $38 )
<font color="#CC3333">CO bets $20.00</font>, Hero calls $20.00,

River: 2[img]/images/graemlins/club.gif[/img] ( $78 )
<font color="#CC3333">CO bets $78.00</font>, Hero ...?

Thoughts on all streets are welcome.