SUMMARYSchodde, R., and J. L. McKean. 1973. The species of the genusPorotia(Paradisaeidae) and their relationships. Emu 73: 145–156.The species ofParotiaare reviewed and re-diagnosed, and their distribution and ecology summarized. Five species are recognized. These, in order of their apparent evolutionary relationships, areP. wahnesi, P. helenae, P. sefilata, P. lawesiiandP. carolae.Infra-specific variation inP. lawesiiis assessed, and the racesexhibitsandfusciorreduced to synonymy.P. helenae, conventionally treated also as a race ofP. lawesii, is considered specifically distinct on morphological and distributional grounds; extensions to its previously recorded range in south-eastern New Guinea are given.Differences in the structure of frontal featherings in adult males are the primary morphological characters separating the species. The termssupra-naral tuftsandforehead crestare introduced to define the feather-groups involved. Species-charcteristic combinations of these feather groups are assumed to be correlated with slight but critical differences in displays. Those species in which frontal feathering is simple are considered primitive types, vizP. wahnesiandP. sefilta; those in which it is complex are thought to be derived, vizP. carolae.From correlations between the various combinations of Frontal feathering with the geographical disposition of the species and the recent (Pliocene-Pleistocene) environmental history of New Guinea, some introgressive hybridization between populations and the selection of recombinants may have occurred inParotia and contributed to the evolution of the species.Notes on arena behaviour inP. lawesiiand on requirements for conservation are appended.