Ganglionus, gen. nov., is described for five species: G. mitigatus, sp. nov., from Costa Rica; G. catenatus, sp. nov., from Costa Rica and Panama; G. undulatus, sp. nov., from Costa Rica and Panama; G. constrictus, sp. nov., from Ecuador; and G. spatulatus, sp. nov., from Colombia. Ganglionus is placed in Derelomini and presents the following putative synapomorphies: male with (1) dorsally tumescent rostrum, (2) posteriorly setose sternum VIII, and (3) apically O-shaped tegmen. Ganglionus is associated with Carludovica Ruíz & Pavón (Cyclanthaceae). Observations on the biology of G. undulatus at La Selva, Costa Rica, indicate that the adults are pollinators. The females oviposit into the staminate flowers of the host inflorescences, and the larvae complete their development in the leaf litter. A cladistic analysis—using Notolomus basalis LeConte, Staminodeus vectoris Franz, and Perelleschus carludovicae (Günther) as outgroups - proposes the relationships (G. mitigatus, ((G. catenatus, G. undulatus), (G. constrictus, G. spatulatus))).