New records and advertisement calls of Ptychadena species from Rwanda

Species of African Grass Frogs (Ptychadena) are notoriously difficult to distinguish based on external morpho-logical characters. Therefore, the geographic range of several species and the number of local species at a given locality are often unclear. However, previous studies have shown that species of Ptychadena possess many external morphological characteristics that allow unequivocal distinction. Furthermore, species of Ptychadena are readily distinguished by their distinct advertisement calls. We herein present the results of our investigation of the diversity of Ptychadena in Rwanda. We report on the presence of a total of seven species, two of which were previously not known to occur in the country, and describe the hitherto unreported advertisement calls of four species. We provide keys to species based both on external morphological characters and on parameters of the advertisement call for all species from Rwanda.