Costularia is a plant genus in the family Cyperaceae.Kew World Checklist of Selected Plant FamiliesGovaerts, R. & Simpson, D.A. (2007). World Checklist of Cyperaceae. Sedges: 1-765. The Board of Trustees of the Royal Botanic Gardens, Kew.Hoenselaar, K., Verdcourt, B. & Beentje, H. (2010). Cyperaceae. Flora of Tropical East Africa: 1-466.Strugnell, A.M. (2006). A checklist of the Spermatophytes of Mt. Mulanje, Malawi. Scripta Botanica Belgica 34: 1-199. It includes 15 species native to southeastern Africa, ranging from South Africa (KwaZulu-Natal and Northern Provinces) through Eswatini, Mozambique, Zimbabwe, and Malawi, and to the islands Madagascar, Réunion, and the Seychelles in the Western Indian Ocean.Larridon I, Rabarivola L, Xanthos M, Muasya AM. 2019. Revision of the Afro-Madagascan genus Costularia (Schoeneae, Cyperaceae): infrageneric relationships and species delimitation. PeerJ 7:e6528 https://doi.org/10.7717/peerj.6528
The genus was formerly circumscribed to include 25 species. A molecular phylogenetic study found that circumscription to include four distinct lineages: Costularia s.s. (11 species) from Africa, Madagascar, the Mascarene Islands and Seychelles. Chamaedendron (five species) from New Caledonia. a group largely conforming to subgenus Lophoschoenus (eight species) from New Caledonia and Malesia that are now considered to be part of a redelimited genus Tetraria. the species Xyroschoenus hornei, which is endemic to the Seychelles. In 2019, the genus was revised to include 15 species, generally corresponding to Costularia s.s. and including a few previously undescribed species.
List of species 15 species are accepted: Costularia andringitrensis Larridon Costularia brevifolia Cherm. Costularia cadetii Larridon Costularia humbertii Bosser Costularia itremoensis Costularia laxa Cherm. Costularia leucocarpa (Ridl.) Pfeiff. Costularia melicoides (Poir.) C.B.Clarke Costularia melleri (Baker) C.B.Clarke Costularia microcarpa (Cherm.) Kük. Costularia natalensis C.B.Clarke Costularia pantopoda (Baker) C.B.Clarke Costularia purpurea Cherm. Costularia robusta (Cherm.) Larridon Costularia xipholepis (Baker) Henriette & Senterre
Formerly placed here Xyroschoenus hornei (as Costularia hornei (C.B.Clarke) Kük.)
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