That's DEFINATELY an eastern spiny. They're a popular game turtle here, we have tons of them.
A 40 long sounds kind of small, I've seen males up the 12 inches but I think 10 inches or smaller is most common, and I'm pretty positive the one in the pic is a male. Good thing because I've seen females 18 inches or larger

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They need pretty good water quality, and I'm fairly sure they benefit from a UVB bulb like most turtles (maybe someone can correct me on that if I'm wrong), and yes they do bask. I see them laying along the shore and on logs constantly when I'm out on my boat. The pet store here in town used to have one too and he would bask with the other turtles, though that's not recommended because they can become injured by other turtles seeing as they have soft shells.
As I understand it they like a deep sand substrate to bury themselves in, but I dunno if that's a requirement or not.
They're heavily carnivores so they need a meaty diet.
Sorry I can't give better info, I've never kept these turtles, but I do enjoy watching them in the wild. Tell me if you ever want any pics, I could get pics of some massive ones, and some good pics of piles of them laying on the shore basking. Some get some really weird colors depending on which river and which part you're in, I guess because of the diet. Definately not because of poor water quality as the places I see them are extremely pristine.