Synopsis of the genus Vitex (Lamiaceae) in the Democratic Republic of the Congo

Abstract

Background and aims – The genus Vitex is revised for the Democratic Republic of the Congo (D.R. Congo), in order to prepare the treatment of the genus for the Flore d’Afrique Centrale. Methods – Herbarium taxonomy. All the relevant material kept in BM, BR, BRLU, COI, K, P, POZG, WAG has been examined, supplemented with recent field observations in S Katanga. Key results – A total of 21 taxa are reported for the study area, i.e. 17 species, 1 subspecies, 3 varieties. Two taxa are new to the D.R. Congo (V. ciliata, V. fischeri var. keniensis). Four taxa (3 species, 1 variety) are endemic to the D.R. Congo (Vitex agelaeifolia var. rufula, V. discoideoglandulosa, V. djumaensis, V. rubroaurantiaca). Two other taxa are subendemic, i.e. have most of their range in D.R. Congo (Vitex congolensis var. thomasii, V. cuspidata). Two new combinations are made (Vitex congolensis var. thomasii, V. fischeri var. keniensis). Nine new synonyms are proposed. A lectotype is designated for 17 names and a second-step lectotype is designated for one name. An identification key is included.