[2] S. gibbus is one in three species of similar sized blood bees in which the females have punctures, instead of merely rugosity, to the posterior of the ocelli.

The female S. gibbus may be separated from the similar S. monilicornis by its wider, less square shaped head, the darker pubescence on the hind tibiae and thinner propodeum.

The wings of female S. gibbus also tend to be darker in color than those in other blood bees and tergites 1 and 3 are often partly darkened.

[2] It has been confirmed as using Halictus quadricinctus, H. rubicundus, H. sexcintus, H. simplex and H. maculatus as hosts, while it is also likely to parasitise Lasioglossum malachurum.

[6] Other species have been claimed but not confirmed, including Andrena vaga and Colletes cunicularius both of which are regarded as unlikely hosts.