Abstract
SummaryWe present a synopsis and an identification key for the 13 species and one subspecies of the African genus Whitfieldia Hook. (Acanthaceae: Acanthoideae: Whitfieldieae). This work is based on the observation and analysis of morphological data from herbarium specimens and photographs of Whitfieldia species, and the study of all the relevant literature on the genus. Whitfieldia latiflos C.B.Clarke ex Stapf from Liberia is reinstated as an accepted species and a full description and illustration are provided. A new subspecies, W. colorata C.B.Clarke ex Stapf subsp. tigrina A.Grall & I.Darbysh., also from Liberia, is described. In addition, W. arnoldiana De Wild. & T.Durand and W. letestui Benoist are treated as synonyms of W. laurentii (Lindau) C.B.Clarke and W. preussii (Lindau) C.B.Clarke respectively for the first time. Eleven names in Whitfieldia are lectotypified. Reference specimens, relevant literature, habitat notes, distribution maps, taxonomic notes and a preliminary assessment of the conservation status and extinction risk are provided for each taxon. Four species are considered to be threatened of which two (W. latiflos and W. rutilans Heine) are assessed as Endangered (EN) while two others (W. purpurata (Benoist) Heine and W. thollonii (Baill.) Benoist) are placed in the Vulnerable (VU) category. In addition, two taxa are assessed as Near Threatened (NT) and one is currently considered to be Data Deficient (DD).
Highlights
Wild plants belonging to the genus Whitfieldia Hook. (Hooker 1845: t.4155) (Acanthaceae: Acanthoideae: Whitfieldieae) grow in the forests of tropical continental Africa from Guinea in the west to Ethiopia in the east, and south to Angola, Zambia and Mozambique, with highest diversity in the Guineo-Congolian phytogeographical region (Vollesen 2008)
Material studied and cited This study is based primarily on the examination of herbarium specimens held at BM, BR, K, P and PRE, together with additional material digitised at BRLU, G, LISC, MO and WAG, transferred to L
In some cases where species are more widely distributed in Africa and the number of specimens is too large to be manually georeferenced (Whitfieldia lateritia, W. elongata), data were first imported into GeoCAT from GBIF and herbarium specimens were consulted to add missing points and allow a calculation of global extent of occurrence (EOO)
Summary
Wild plants belonging to the genus Whitfieldia Hook. (Hooker 1845: t.4155) (Acanthaceae: Acanthoideae: Whitfieldieae) grow in the forests of tropical continental Africa from Guinea in the west to Ethiopia in the east, and south to Angola, Zambia and Mozambique, with highest diversity in the Guineo-Congolian phytogeographical region (Vollesen 2008). Other useful traits for the identification of core Whitfieldieae include left-contort corolla aestivation (Manktelow et al 2001 record imbricate aestivation in Whitfieldieae but this has not so far been observed by the current authors); an androecium of four stamens or very rarely two stamens and two staminodes with no filament curtain for all species (Manktelow et al 2001; Tripp et al 2013); and each floral or cymose unit being subtended by paired bracts (or bracteoles). These bracts are usually conspicuous and clasping or partially connate and often partially or entirely enclose the calyces. The present work aims to provide an identification key to species within the genus and a synoptic account of the recognised taxa, including distribution maps, notes on habitat requirements, citation of voucher specimens and, where available, illustrations to help in the identification of this fascinating group
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
