The taxonomic limits of the Malagasy genus Piasites Seyrig are reviewed. The genus is redescribed and compared to other similar taxa, especially the Afrotropical Bozakites Seyrig. The type species, P. carinatus Seyrig, is redescribed; its extensive colour variation is described and discussed. Seven new species are described and illustrated: P. lineatus, P. nigricollis, P. orbitalis, P. perinetensis, P. politus, P. quasimodus and P. seyrigi. An identification key to the species is presented.