This beetle came to a UV light. In your display of this genus, you show only one species, H. marginicollis, which is similarly illustrated in Evans' book. Yet, Downey and Arnett list H. sphaericula as the only northeastern species in that genus. That would appear to make H. sphaericula a synonym of H. marginicollis, except that ITIS lists both species as being valid. H. marginicollis (LeConte, 1852) does have priority over H. sphaericula (Casey, 1900), if they are one and the same thing. Is this how have you come down in favor of H. marginicollis?