While looking up Tom's Hoplia, I noticed that Anomala luciola is fairly common up our way, and is completely dark like this one, while all of our New England A. orientalis are basically pale with dark markings. I don't know Anomala species (except for typical orientalis), but this looked suspicious to me.

Tom has some black beetles from Massachusetts that are identified as A. orientalis (I have no idea if the identification is correct):

preliminary investigation reveals both are common here, the character to separate the two is on the venter, and both vary from completely yellow to all black. Requires more investigation, some day in the future.

I can only tell the all dark forms apart by pronotal punctation, denser/closer in A. orientalis, sparser/more distant in A. lucicola. This looks like A. orientalis to me, no guarantees. One of Tom's other photos looks like A. lucicola.

Thanks for the ID, Phillip. This one was blacker than the photos; I lightened the shadows for detail. Based on the Info page, it sounds like it emerged earlier than it should have, which would jibe with "houseplant".