Morphological comparison of a poorly known scorpionfish, Parapterois macrura, with a related species, P. heterura (Scorpaenidae: Pteroinae). Zoological Studies 43(1): 1-7. The taxonomic status of a scorpionfish Parapterois macrura (Scorpaenidae: Pteroinae), originally described as Pterois macrura from the Malabar Coast off Calicut, west coast of India by Alcock (1896), has long been in doubt. Comparison of P. macrura collected from Indian waters with a related congener P. heterura (Bleeker, 1856), originally described from Ambon, Indonesia and subsequently collected from the southeast coast of Africa and western Pacific Ocean, revealed that the former was distinguished from P. heterura by the following characters: a scaleless interorbital space, lower counts of longitudinal scale series, greater head and snout lengths and head depth, a shorter tentacle on the posterior spine of the lacrimal, the upper margin of the orbit higher than or level with the base of the first dorsal spine (in lateral view) in adults and top of a bulge on the snout much lower than the ventralmost margin of the orbit (in lateral view) in adults. Morphological changes with growth for both species and populations in P. heterura are also discussed.