  We propose an extension of the standard model of quarks and leptons to
include gauge $B-L$ symmetry with an exotic array of neutral fermion singlets
for anomaly cancellation. With the addition of suitable scalars also
transforming under $U(1)_{B-L}$, this becomes a model of radiative seesaw
neutrino mass with possible multipartite dark matter. If leptoquark fermions
are added, necessarily also transforming under $B-L$, the diphoton excess at
750 GeV, recently observed at the Large Hadron Collider, may also be explained.
