Protomagalhaensia blaberae Peregrine, 1970 is redescribed from the type host, the Bolivian cockroach Blaberus boliviensis. Complete morphometric data on all life cycle stages is presented, the taxon is stabilized with the deposition of new voucher specimen material, and P. blaberae is distinguished from all other species in the genus (Protomagalhaensia cerastes, Protomagalhaensia granulosae, and Protomagalhaensia wolfi). Species of Protomagalhaensia are distinguished by differences in relative metric ratios, morphology of oocysts, and by relative metric ratios of mature gamonts in association. The status of Protomagalhaensia serpentula is considered and the taxon is determined species inquirenda.