The picture for the Nar pepper shown on the pepperlover web page has a clear constricted calyx.
It's most likely mislabeled as a baccatum, but the only way to know for sure is to grow it out.
The pepper looked like a C.Chinense to me, except for the single pod at the node ( C. Chinense usually has multiple pods). But this isn't written in stone. You're right, I'll just grow it this year and solve the mystery. Thanks for the reply.