Diaphenchelys pelonates genus and species novum, subfamily Muraeninae, is described from three specimens collected along mud slopes at 15–32 m off Maumere Bay, Flores Island, Indonesia. Diaphenchelys differs from all known muraenids in collectively having an elongate body, a short snout, moderately elongate jaws that are not strongly recurved, biserial maxillary dentition with an inner row of ... [Show full abstract] enlarged con-ical teeth, and mean vertebral formula 6/56/154. Although most similar in appear-ance to species of Gymnothorax, it is most closely related to species of Enchelycore. The occupation of mud habitats is very uncommon for muraenids and the facial col-oration and pore reduction adaptations of the new species are probably linked to that habitat. During three diving expeditions to Flores, Indonesia, the second author observed a species of moray eel living along a mud slope in Maumere Bay. Unable to recognize it, he collected and pho-tographed three individuals, shared them with the senior author, and after careful examination we were unable to assign them to any known muraenid genus. At first appearance, they appear similar to species of Gymnothorax (sensu lato), however, upon closer examination of the teeth and other characteristics, we were unable to place them within any known subgenus of Gymnothorax. They share several specializations with the species of Enchelycore but lack the prominent hooked jaws, elongate neurocranium, and other specializations of those species. Mud bottoms are not common habitats for most morays and we suspect that some of the distinctive characters of the new species are associated with living in mud. Pending a comprehensive revision of the family Muraenidae, we are cautious in describing a new genus along with our new species; however, we remain satisfied that in the evolution of moray eels, this too is a monotypic muraenid endeavor.