The endemic Sri Lankan synbranchid 'Monopterus' desilvai is redescribed based on additional material. In life, individuals have a maroon background colour with numerous dark brown blotches. They breathe air, which is stored in paired suprabranchial pouches. The head skeleton of M. desilvai is described in detail. This species shares with M. cuchia, M. indicus, M. fossorius, M. ichthyophoides, M. rongsaw, M. luticolus, and M. boueti derived and unique modifications of the gill arch skeleton: ceratobranchial 1 is spatially removed from hypobranchial 1 and aligned with hypo-and ceratobranchial 2, leading to a separation of the anterior from the posterior gill arch skeleton. It shares with M. cuchia, M. indicus, M. fossorius, and M. ichthyophoides an even further derived gill arch skeleton, in which epibranchial 1, the interarcual bone and pharyngobranchial 2 are absent, modifications puta-tively related to the evolution of paired suprabranchial pouches in these species. Based on these shared derived characters the group comprising M. cuchia, M. indicus, M. fossorius, M. ichthyophoides and M. desilvai, is recognized as a monophyletic unit for which the oldest available generic name is Ophichthys Swainson.