Notes on Atriplex, Oxybasis and Dysphania (Chenopodiaceae) in West-Central Tropical Africa

Background and aims - The indigenous representatives of Chenopodiaceae in tropical Africa are still insufficiently studied. Some genera, especially Atriplex L., Oxybasis Kar. & Kir. and Dysphania R.Br. (subfam. Chenopodioideae), are difficult to diagnose and are often confused with other native or alien taxa. Methods - The morphological characters of Atriplex, Oxybasis and Dysphania were reviewed using specimens from the herbaria B, BM, BR, BRLU, E, G, K, LE, MHA, MW, P, and W. Key results - A new species Atriplex congolensis Sukhor. is described from the highlands of D.R.Congo and illustrated. It was previously cited as A. hastata L. (now A. prostrata Boucher ex DC.) and is the only species of Atriplex sect. Teutliopsis Dumort. emend. Sukhor. in tropical Africa. A morphological comparison of all Atriplex representatives encountered in Africa (A. chenopodioides Batt., A. congolensis Sukhor., A. davisii Aellen, A. nilotica Sukhor., A. patula L., A. prostrata Boucher ex DC., and A. verreauxii Moq.) is provided. All records of the rare native Dysphania congolana (Hauman) Mosyakin & Clemants in mountainous tropical Africa are mapped using previously known and re-identified locations. Oxybasis chenopodioides is newly reported for D.R.Congo. The lectotype of Chenopodium glaucum L. subsp. congolanum Hauman (Dysphania congolana) is designated. It is pointed out that D. congolana cannot be considered a close relative to any American taxon despite morphological similarities.