Costularia is a plant genus in the family Cyperaceae. It includes four distinct lineages: 1. * Costularia s.s. (11 subspecies) from Africa, Madagascar, the Mascarene Islands and Seychelles. 2. * Chamaedendron Larridon (five subspecies) from New Caledonia. 3. * a group largely conforming to subgenus, Lophoschoenus (eight subspecies) from New Caledonia and Malesia that are now considered to be part of a redelimited genus Tetraria, which are found on the island of Madagascar. 4. * the species Xyroschoenus hornei which is endemic to the Seychelles.