A kawaio penak , a new genus and species, is described from the upper M azaruni R iver, G uyana. The new species is diagnosed from all other species of H ypopomidae by several anatomical traits. The phylogenetic affinities of the new genus were inferred using data from one nuclear (rag2) and two mitochondrial ( COI and cyt b ) genes. The phylogenetic analyses indicate that A kawaio is the sister taxon of a clade that includes B rachyhypopomus , H ypopomus , M icrosternarchus and R acenisia . These results provide evidence for the phylogenetic composition of H ypopomidae supported by previous molecular studies and support the position of the S teatogenini ( H ypopygus + S teatogenys ) as the sister group of R hamphichthys + G ymnorhamphichthys . The description of this new electric knifefish increases the total number of endemic genera and species in the upper M azaruni, a region that is suffering freshwater habitat degradation as consequence of gold‐mining activities.