A new species of the cosmopolitan genus Eudendrium, E. klausi, is described from Carrie Bow Cay, Belize. The species is characterized by a small colony with an intense blue colour, polyps armoured with large microbasic euryteles scattered on the hydranth body, hypostome, and female spadix; female gonophores on normal hydranths with a reduced number of tentacles. The new species is compared to other Eudendrium with similar cnidome, and other Caribbean species, including those described by Allman (1877). Among the latter, E. gracile, E. laxum, E. attenuatum, and E. tenellum (sensu Allman) are considered as species inquirenda due to the lack or the unsuitability of the type materials and the inconclusive original descriptions. Eudendrium exiguum, E. eximium, and E. fruticosum were also studied and demonstrated to be different from E. klausi sp. nov.