Key to species of Philometra

1 Female mouth opening oval; 14 cephalic papillae arranged in two circles; subgravid worms <60 mm long; oesophagus rela- tively long (> 3 mm)............................................................................. P. rubra

- Female mouth opening round; four cephalic papillae; gravid worms> 90 mm long; oesophagus relatively short (<3 mm).. 2

2 Female tail rounded, bearing two small lateral papillae............................................. P. cylindracea

- Female tail tapers, bearing small dorsally directed papilla............................................. P. kobuleji