Pronephrium thwaitesii, known only from two collections from Ceylon and one from South India, all made more than a century ago and not found any more in these localities, is reported from Silent Valley (Malabar, South India) and described. It is a sterile hybrid possibly between P. triphyllum and Christella parasitica (not Trigonospora ciliata or P. articulatum as hitherto suggested).