Name changes in Podostemaceae

While preparing a review of the family Podostemaceae, we have found it necessary to change the name of some species. Following rules of priority, Crenias K. P. J. Sprengel replaces Mniopsis Martius. No convincing reasons can be found to maintain the monotypic genera Hydrobryopsis, Malaccotristicha, Synstylis and Torrenticola; they are merged in their sister genera Zeylanidium, Tristicha, Hydrobryum and Cladopus, respectively. On morphological grounds Polypleurella micranthera is transferred to Hydrobryum and Polypleurum submersa is transferred to Saxicolella.