Systematic Botany (2010), 35(2): pp. 325–340 © Copyright 2010 by the American Society of Plant Taxonomists Taxonomy of Wiborgiella (Crotalarieae, Fabaceae), a Genus Endemic to the Greater Cape Region of South Africa James S. Boatwright, 1 , 2 , 3 Patricia M. Tilney, 1 and Ben-Erik van Wyk 1 1 Department of Botany and Plant Biotechnology, University of Johannesburg, P. O. Box 524, Auckland Park 2006, Johannesburg, South Africa 2 Current address: Compton Herbarium, South African National Biodiversity Institute, Private Bag X7, Claremont, 7735 South Africa 3 Author for correspondence ( [email protected] ) Communicating Editor: Marty Wojciechowski Abstract— A taxonomic revision of the recently described genus Wiborgiella is presented. Nine species are recognized within the genus, two of which are newly described, W. dahlgrenii and W. vlokii . The genus is endemic to the Cape region of South Africa and most species are highly localized and rare. Wiborgiella species can be distinguished from other genera in the tribe Crotalarieae by a combination of brown young branches (early formation of bark in the stems of the perennial species), laminar trifoliolate leaves, glabrous petals, a 4 + 6 anther arrange- ment, and oblong, wingless, inflated fruit. Anatomical studies revealed that all species of the genus have dorsiventral leaves (mesophyll dif- ferentiated into palisade parenchyma adaxially and spongy parenchyma abaxially) with mucilage cells in the epidermis which distinguishes Wiborgiella from other closely related genera, such as Calobota which has isobilateral leaves without mucilage cells. The fruits of Wiborgiella species are all thin-walled, have highly sclerified mesocarps and mucilage cells are present in some species. These fruit character states are also present in other genera of the Crotalarieae. The taxonomic treatment of the genus includes a key to the species, descriptions, illustrations, nomenclature, typification, and geographical distribution of each species. Keywords— Anatomy , Cape Crotalarieae , Fabaceae , South Africa , Taxonomy, Wiborgiella. Wiborgiella Boatwr. and B.-E. van Wyk was proposed as morphological data, in order to test the monophyly of a new generic concept to accommodate nine species that Wiborgiella . are endemic to the Greater Cape region of South Africa (Boatwright et al. 2009 ). The description of the genus fol- lowed a phylogenetic study of the tribe Crotalarieae which Materials and Methods showed that the genus Lebeckia Thunb., of which the Morphology— Morphological data were obtained through the study of Wiborgiella species formed a part, is polyphyletic ( Boatwright herbarium specimens as well as fresh material collected during field excur- et al. 2008 ). The molecular results, together with morpho- sions. Several collecting trips provided opportunities to study the plants in their natural environment and to collect fresh material. Plant material for logical and anatomical data, indicated that Lebeckia s. l. morphological analysis and anatomical study was preserved in FAA ( Sass should be divided into three genera: Lebeckia s. s., Calobota 1958 ; formaldehyde: acetic acid: 96% alcohol: water; 10:5:50:35) and silica Eckl. and Zeyh., and Wiborgiella . Wiborgiella comprises all ( Chase and Hill 1991 ). All specimens collected are housed in the University the species that were previously included in Lebeckia section of Johannesburg Herbarium ( JRAU). Specimens of Wiborgiella from the fol- lowing herbaria were studied either on site or on loan: BM, BOL, GRA, Viborgioides Benth., along with the anomalous Lebeckia inflata JRAU, K, NBG (including SAM and STE), P, PRE, S, UPS, and WIND (abbre- Bolus, L. mucronata Benth., and, surprisingly, also Wiborgia viations follow Holmgren et al. 1990 ). Selected electronic images from TCD humilis (Thunb.) R. Dahlgren. Although the monophyly of were also studied. Measurements and observations were done among sev- Wiborgiella did not receive support in the phylogenetic anal- eral geographically isolated populations by arranging the material studied yses, Boatwright et al. (2009) present further evidence that a according to geographical distribution. At least three measurements per specimen were made where possible. The following floral characters were combination of salient morphological and anatomical char- recorded from dissections of mature flowers from material fixed in FAA or acters supports the recognition of this group at the generic flowers rehydrated from rich herbarium specimens: pedicel length, length level. of the bracts and bracteoles, flower length, length of the calyx, length of During his revision of Wiborgia Thunb., Dahlgren (1975) also the calyx tube, depth of the upper, lateral and lower sinuses of the calyx, studied Lebeckia section Viborgioides because these two groups width of the upper, lower and lateral calyx lobes, length and width of the standard-, wing-, and keel petals, and the length of the claws of each petal. are superficially similar. He suggested that the taxa might be Specimens from which dissections were made are listed in Boatwright congeneric, but from the data of Boatwright et al. (2008) it is (2009) . Drawings of vegetative and reproductive structures were done clear that Wiborgia is a strongly supported group. Wiborgiella using a stereoscope (WILD M3Z) with a camera lucida attachment. All can be distinguished from Calobota , Lebeckia s. s., and Wiborgia drawings were done by the first author. Author citations for Wiborgiella species are given in the taxonomic section and not repeated elsewhere. by a unique combination of characters: early bark formation Data on the distribution of the various species are presented as maps. (with the exception of the short-lived Wiborgiella inflata and These data were gathered from herbarium material, field notes, as well W. vlokii ), laminar trifoliolate leaves, glabrous petals, a 4 + 6 as from Leistner and Morris (1976 ; for southern African taxa). The dis- anther arrangement, and oblong, wingless, much inflated tribution data for each species was recorded using the Quarter Degree fruits (with the exception of W. vlokii which has laterally com- Reference System ( Edwards and Leistner 1971 ; also outlined in Leistner and Morris 1976 ). The basic unit in this system is the one-degree square of pressed fruits). latitude and longitude, which is designated by a degree reference number This paper presents a taxonomic revision of the genus (i.e. degrees of latitude and longitude of the north-west corner) and the Wiborgiella including a key to the species, complete nomen- district name of that square. clature, typification, formal descriptions, known geo- Anatomy— Fresh material was fixed in FAA and dry material was first rehydrated by briefly boiling in distilled water and then fixed in FAA for graphical distributions, and illustrations of all the species. 24 hr. A modification of the method of Feder and O’Brien (1968) was used In addition a phylogenetic analysis of the “Cape group” for embedding in glycol methacrylate (GMA), where the final infiltration of the Crotalarieae is presented, based on molecular and in GMA was done for a minimum of five days. Sections were stained 325 326 SYSTEMATIC BOTANY [Volume 35 according to the periodic acid Schiff/toluidine blue (PAS/TB) staining Wiborgia species have a similar habit and stem structure to method ( Feder and O’Brien 1968 ) and mounted. Voucher information Wiborgiella ( Fig. 2 ). for the material used in the anatomical studies is listed in Appendix 1. Photographs were taken with a JVC KY-F1030 digital camera. Leaves of Wiborgiella species are invariably laminar, trifoli- Phylogenetic Analyses— The combined molecular matrix of Boat- olate, and petiolate (sessile on older branches of W. sessilifo- wright et al. (2008 ; TreeBASE study number S2070) was used to perform lia ). The petioles of the shrubby species have a swollen base a combined molecular/morphological analysis of the “Cape group” of or tubercle and are persistent even after the leaflets have been the Crotalarieae (sensu Boatwright et al. 2008 ; including Aspalathus L., shed. The branches in most perennial species become hard and Calobota , Lebeckia , Rafnia Thunb., Wiborgia, and Wiborgiella ) to test the monophyly of Wiborgiella . Boatwright et al. (unpublished data) have pungent after flowering and have a thorn-like appearance sim- shown that Lotononis macrocarpa Eckl. and Zeyh. shares a sister relation- ilar to most Wiborgia species ( Dahlgren 1975 ). The persistent ship with the genera of the “Cape group” of the Crotalarieae and it was petioles along with the somewhat spinescent branches give therefore added to the matrices as outgroup. Sequence data (nrITS and these plants a rigid appearance. Transverse sections through plastid rbcL ) of the relevant taxa were combined with 12 morphologi- cal characters that were coded for each species in the matrix using the the leaflets of all Wiborgiella species revealed that the leaves are outgroup method of comparison. This morphological matrix and the dorsiventral (mesophyll clearly differentiated into palisade character state polarizations are given in Appendix 2 and Supplemental parenchyma adaxially and spongy parenchyma abaxially) and (online) Appendix 3. Parsimony analyses were performed as outlined in that they have mucilage cells in the epidermis ( Fig. 2 ). This is Boatwright et al. (2008) . a reliable distinguishing character to separate Wiborgiella from Evolution of Morphological Characters— Morphological characters were