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 and nuclear ITS sequences. Kewa is strongly supported and the included species have strong to no support, whereas the relationships between the species are mostly unsupported. The phylogeny is dated and the estimated age of the Kewa stem clade is (37.5‐)45.0(‐57.0) million years and of the crown clade (3.0‐)3.9(‐7.4) million years. The age of the crown clade would also be the estimated date when K. acida on the approximately 14 million years old St. Helena diverged from its potential sister group on the African continent, and would coincide with the earliest possible date for the introduction of the ancestor of K. acida to St. Helena.
voucher_table
A tab-delimited text file of the individuals sampled for the phylogenetic analyses with voucher information and GenBank accession numbers.
alignment_trimmed.nex
Trimmed alignment used in analyses in nexus format. Order of regions is ITS (bases 1-664), followed by trnK-matK (bases 665-3418), followed by rbcL (bases 3419-4799).
alignment_untrimmed.nex
Untrimmed original alignment in nexus format. Order of regions is ITS (1-664), followed by trnK-matK (bases 665-3668), followed by rbcL (bases 3669-5518).
Fig_S1.pdf
Fig. S1. Best tree from the RAxML analysis of the combined trnK-matK and rbcL core Caryophyllales dataset showing branch lengths. Branch labels show bootstrap values from 1000 bootstrap rep¬licates. When more than one accession per species was included, the localities after the names correspond to those in Appendix 1. SAfr refers to South Africa.
Fig_S2.pdf
Fig. S2. Best tree from the RAxML analysis of the ITS Kewa dataset showing branch lengths. Branch labels show bootstrap values from 1000 bootstrap rep¬licates. When more than one accession per species was included, the localities after the names correspond to those in Appendix 1. SAfr refers to South Africa.
Fig_S3.pdf
Fig. S3. Best tree from the RAxML analysis of the combined trnK-matK, rbcL, and ITS, core Caryophyllales dataset showing branch lengths. Branch labels show bootstrap values from 1000 bootstrap rep¬licates. When more than one accession per species was included, the localities after the names correspond to those in Appendix 1. SAfr refers to South Africa.
Fig_S4.pdf
Fig. S4. MrBayes analysis of the combined trnK-matK, rbcL, and ITS, core Caryophyllales dataset. Branch labels show Bayesian posterior probabilities. When more than one accession per species was included, the localities after the names correspond to those in Appendix 1. SAfr refers to South Africa.
Fig_S5.pdf
Fig. S5. BEAST analysis of the combined trnK-matK, rbcL, and ITS, core Caryophyllales dataset. Node labels represent median divergence time estimates (Ma). Blue node bars represent 95% HPD. When more than one accession per species was included, the localities after the names correspond to those in Appendix 1. SAfr refers to South Africa.
Fig_S1.tre
Fig. S1 tree. Best tree from the RAxML analysis of the combined trnK-matK and rbcL core Caryophyllales dataset showing branch lengths, in nexus format. Branch labels show bootstrap values from 1000 bootstrap rep¬licates.
Fig_S2.tre
Fig. S2 tree. Best tree from the RAxML analysis of the ITS Kewa dataset showing branch lengths, in nexus format. Branch labels show bootstrap values from 1000 bootstrap rep¬licates.
Fig_S3.tre
Fig. S3 tree. Best tree from the RAxML analysis of the combined trnK-matK, rbcL, and ITS, core Caryophyllales dataset showing branch lengths, in nexus format. Branch labels show bootstrap values from 1000 bootstrap rep¬licates.
Fig_S4.tre
Fig. S4 tree. MrBayes analysis of the combined trnK-matK, rbcL, and ITS, core Caryophyllales dataset, in nexus format. Branch labels show Bayesian posterior probabilities.
Fig_1_S5.tre
Fig. 1 and S5 tree. BEAST analysis of the combined trnK-matK, rbcL, and ITS, core Caryophyllales dataset, in nexus format. Node labels represent median divergence time estimates (Ma).
