If we were able to examine the spurs on the hind legs it would be easy to separate Lasioglossum bicingulatum from L. tertium. From photos, the only criterion that I can use is that L. tertium has only two hair bands on the metasoma. One day, somebody may find a tertium specimen with a third hair band but until then it is reasonable to use the rule that bicingulatum has three bands and tertium two.