 This rail is related to the New Guinea flightless rail , Megacrex <unk> , and the chestnut rail , <unk> <unk> , all three <unk> genera probably being derived from <unk> ancestors . <unk> <unk> argued that the genus Megacrex was so similar to Habroptila that Megacrex should be considered a junior synonym of Habroptila , resulting in two species in the genus . This was further <unk> in Sidney Dillon Ripley 's 1977 <unk> of the <unk> ; he included Habroptila within the large genus <unk> . This suggestion was , however , not accepted by <unk> <unk> <unk> , who pointed out distinct differences in the shape and structure of the bill . A molecular phylogenetic analysis based on mitochondrial DNA sequence similarity found that Habroptila is part of evolutionary radiation within the broad genus <unk> that took place around 400 @,@ 000 years ago in the region . 
