What features distinguish Orthoperus from similar genera?

basically, Orthoperus are the most 'coccinellid-like' convex beetles of them all; the only other option i can't exclude in this case is Holopsis, all the rest being flattened to various degrees and having pronotum either more 'roach-like' or with prominent, shoulder-embracing rear angles. AmerBeetles provide a helpful array of dorsal pictures -- good enough to give one an idea of what diff. genera look like (of course, if you've seen some live specimens before)

I see it's convex on bottom as well as top.

is that the bratwurst antennal base (you nailed it!) & pronotal hind angles are more consistent with Holopsis... SO pls make the new genus page for it. The rest of what's under Orthoperus seems to be placed correctly.
== Thank you for pressing me out of my mistake -- AND TRY TO CATCH MORE OF THESE ==

I think it's worth noting that Holopsis is absent from the UNH checklist. Could it be known by a new genus name like Clypa*strea (Mola*mba)? If not and if accurately IDed to genus, this may be another state record.

I'm glad of course to get another genus. It did seem to lean a little toward the Sericoder*us body shape I thought, which was why I asked for distinguishing traits.

-- you'll immediately recognize it, you've shot them before (see BGuide page); an Seric. is the easiest of them all to ID even it's the first corylophid you've ever caught