Costularia

Costularia is a plant genus in the family Cyperaceae.^[2][3][4][5] 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.^[1][6]

Costularia
Costularia sp.
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Clade:	Commelinids
Order:	Poales
Family:	Cyperaceae
Genus:	Costularia C.B.Clarke
Synonyms[1]
Cyclocampe Benth. & Hook.f. (1883), nom. illeg. Lophoschoenus Stapf (1914)

The genus was formerly circumscribed to include 25 species. A molecular phylogenetic study found that circumscription to include four distinct lineages:

1. Costularia s.s. (11 species) from Africa, Madagascar, the Mascarene Islands and Seychelles.
2. Chamaedendron Larridon (five species) from New Caledonia.
3. 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.
4. 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.^[6]

List of species

15 species are accepted:^[1]

• Costularia andringitrensis Larridon
• Costularia brevifolia Cherm.
• Costularia cadetii Larridon
• Costularia humbertii Bosser
• Costularia itremoensis Larridon
• 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.)

References

1. Costularia C.B.Clarke. Plants of the World Online. Retrieved 11 November 2023.
2. Kew World Checklist of Selected Plant Families
3. Govaerts, R. & Simpson, D.A. (2007). World Checklist of Cyperaceae. Sedges: 1-765. The Board of Trustees of the Royal Botanic Gardens, Kew.
4. Hoenselaar, K., Verdcourt, B. & Beentje, H. (2010). Cyperaceae. Flora of Tropical East Africa: 1-466.
5. Strugnell, A.M. (2006). A checklist of the Spermatophytes of Mt. Mulanje, Malawi. Scripta Botanica Belgica 34: 1-199.
6. 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