Résumé : Presently two species of the genus Merona are known: Merona comucopiae Norman, 1864 and Merona operculata Watson, 1978. A hitherto unknown species is described herein as M. ibera sp. nov., and compared with these two. It has gastrozooids and dactylozooids similar to those of M. comucopiae, but its female gonozooids are different, being smaller and having the gonophores placed distally. The gonophores contain many small eggs and have a ‘button’ of nematocysts (microbasic euryteles) at the tip. © 1993 Taylor & Francis Ltd.