Specimens of the freshwater marginellid Rivomarginella electrum (Reeve) were collected in South Sumatra. The erroneous spelling of the type locality is corrected into Lake Jepara. The animal, radula and ecology are described for the first time; living specimens were observed in an aquarium. The species is compared with R. morrisoni Brandt from Thailand. Differences in shell, animal and radula prove that the two are distinct species. The genus Rivomarginella seems to be related to Volvarina.