Phylogeny and systematics of Kewa (Kewaceae)

The genus Kewa in the monogeneric family Kewaceae (Caryophyllales) is revised. Six species are recognized, K. acida on St. Helena, K. angrae-pequenae in Namibia and South Africa, K. arenicola (incl. K. trachysperma) in South Africa, K. bowkeriana (incl. K. suffruticosa) widespread in eastern and southern Africa and in Madagascar, K. caespitosa in Angola and Namibia, and K. salsoloides in Namibia, Botswana, and South Africa. Kewa is morphologically distinctive, notably by its simple perianth where the two outer perianth-segments are more or less sepaloid and the three inner ones more or less petaloid, and by its indumentum of short glandular hairs, often with prominent, persistent, wart-like bases. All species have an acid taste, apparently due to the presence of oxalic acid. All names are typified, including one lectotype designated here. An identification key and distribution maps for all species are provided. The phylogeny of Kewa is reconstructed based on plastid trnK-matK and rbcL a...