Field Notes: Turtle ID help requested

Most of the turtles in our local fresh waters are eastern red eared sliders (Trachemys scripta elegans). I posted a picture of two of them last week in Green-Wood; note the distinctive red stripe behind the eye; note also that rough carapace. This is an invasive species, now pretty naturalized, that was, and I suppose continues to be, spread by the pet turtle trade. It’s illegal to release turtles, but of course that doesn’t stop anybody.

On Saturday, in the Japanese Garden in the Brooklyn Botanic Garden, I counted 18 sliders piled up on rocks by the bridge, sunning themselves after the long cold winter. And then I spotted the one pictured above and below.
Note the smooth carapace, and those lovely splashes of red. I think this is a painted turtle (Chrysemys picta). According to the herps at Hofstra U, we have four subspeices of C. picta in the U.S., but this one does not seem to be the eastern subspecies, C. picta picta. Those scutes are definitely not in straight rows. What do you think?