P. V. Bruyns

A revised classification of the Apocynaceae s.l.

The Asclepiadaceae, as traditionally defined, have repeatedly been shown to be an apomorphic derivative of the Apocynaceae. It has often been recommended that the Asclepiadaceae be subsumed within the Apocynaceae in order to make the latter monophyletic. To date, however, no comprehensive, unified classification has been established. Here we provide a unified classification for the Apocynaceae, which consists of 424 genera distributed among five subfamilies: Rauvolfioideae, Apocynoideae, Periplocoideae, Secamonoideae, and Asclepiadoideae. Keys to the subfamilies and tribes are provided, with lists of genera that (as far as we have been able to ascertain) are recognized in each tribe.ZusammenfassungEs wurde wiederholt festgestellt, dass die Asclepiadaceae in der traditionellen Umgrenzung ein apomorphes Derivat der Apocynaceae sind. Deshalb wurde oft vorgeschlagen, sie bei den Apocynaceae unterzubringen, damit die Apocynaceae eine monophyletische Gruppe darstellen. Bis jetzt wurde aber keine eingehende kombinierte Klassifikation publiziert. Hier stellen wir eine kombinierte Klassifikation vor für die Apocynaceae, mit 424 Gattungen, die in fünf Unterfamilien gegliedert sind: Rauvolfioideae, Apocynoideae, Periplocoideae, Secamonoideae und Asclepiadoideae. Schlüssel zu den Unterfamilien sowie den Triben werden gegeben. Die Gattungen, die zu jeder Tribus gehören (soweit bekannt) werden aufgelistet.

A new subgeneric classification for Euphorbia (Euphorbiaceae) in southern Africa based on ITS and psbA-trnH sequence data

We use data from the internal transcribed spacer (ITS) region of the nuclear rDNA cistron and the chloroplast psbA-trnH intergenic spacer to reconstruct the phylogenetic relationships among southern African species of Euphorbia. The results indicate that major re-organization is necessary of the groupings within Euphorbia that have been recognised in the past, since most of them turn out to be polyphyletic. Furthermore, in its present circumscription, Euphorbia itself is not monophyletic, nor do the southern African species form a monophyletic group. Both datasets show that the southern African species fall into four major groups, which we recognise as subgenera: Chamaesyce Raf., Esula Pers., Euphorbia and Rhizanthium (Boiss.) Wheeler. To accommodate the southern African species, subg. Chamaesyce is divided into sect. Chamaesyce, sect. Frondosae Bruyns, sect. nov., sect. Articulofruticosae Bruyns, sect. nov. and sect. Espinosae Pax & Hoffm. Subgenus Euphorbia is divided into sect. Euphorbia, sect. Monadenium (Pax) Bruyns, sect. Goniostema H. Baill. ex Boiss. and sect. Tirucalli Boiss. To re-establish the monophyly of Euphorbia, the genera Endadenium L.C. Leach, Monadenium Pax and Synadenium Boiss. are reduced to synonymy under Euphorbia subg. Euphorbia sect. Monadenium and the species are all transferred to Euphorbia. Consequently the subtribe Euphorbiinae now consists of the single, very large, very widely distributed and very diverse genus Euphorbia. Three of the subgenera (Chamaesyce, Esula, Euphorbia) are nearly cosmopolitan, showing the great age and wide extent of the radiation that has occurred within Euphorbia. The remaining subg. Rhizanthium is mainly African.

A worldwide molecular phylogeny and classification of the leafy spurges, Euphorbia subgenus Esula (Euphorbiaceae)

The leafy spurges, Euphorbia subg. Esula, make up one of four main lineages in Euphorbia. The subgenus comprises about 480 species, most of which are annual or perennial herbs, but with a small number of dendroid shrubs and nearly leafless, pencil-stemmed succulents as well. The subgenus constitutes the primary northern temperate radiation in Euphorbia. While the subgenus is most diverse from central Asia to the Mediterranean region, members of the group also occur in Africa, in the Indo-Pacific region, and in the New World. We have assembled the largest worldwide sampling of the group to date (273 spp.), representing most of the taxonomic and geographic breadth of the subgenus. We performed phylogenetic analyses of sequence data from the nuclear ribosomal ITS and plastid ndhF regions. Our individual and combined analyses produced well-resolved phylogenies that confirm many of the previously recognized clades and also establish a number of novel groupings and place- ments of previously enigmatic species. Euphorbia subg. Esula has a clear Eurasian center of diversity, and we provide evidence for four independent arrivals to the New World and three separate colonizations of tropical and southern Africa. One of the latter groups further extends to Madagascar and New Zealand, and to more isolated islands such as Reunion and Samoa. Our results confirm that the dendroid shrub and stem-succulent growth forms are derived conditions in E. subg. Esula. Stem- succulents arose twice in the subgenus and dendroid shrubs three times. Based on the molecular phylogeny, we propose a new classification for E. subg. Esula that recognizes 21 sections (four of them newly described and two elevated from subsectional rank), and we place over 95% of the accepted species in the subgenus into this new classification.

Recircumscription of the Stapelieae (Asclepiadaceae)

The infrafamilial classification of the Asclepiadaceae has been investigated from the nomenclatural side by Sundell (1980) who indicated that this classification has been based almost entirely on the subdivisions of the family made by R. Brown (1810). Some of the nomenclatural aspects concerning the typification and first valid publication of the tribal names Ceropegieae, Stapelieae and Marsdenieae have been further discussed by Swarupanandan (1983) and revolve around the typification of Pergularia L. and tribal names based on this taxon.

Three new succulent species of Apocynaceae (Asclepiadoideae) from southern Africa

Summary. Three new species of Apocynaceae - Asclepiadoideae are described. They are Ceropegia namaquensis and Ceropegia leptophylla of the tribe Ceropegieae from South Africa and Sarcostemma oresbium from Mozambique of the tribe Asclepiadeae. The genus Ceropegia L. contains some 200 species which are distributed from southern Africa around the perimeter of the Indian Ocean to Australia. Since the revision of the southern African species by R. A. Dyer (Dyer 1980), relatively few new species of Ceropegia have been described from southern Africa. However, the arid parts of the region are botanically not well known even today and two rare new species have been found in them which are described in this paper. In addition, a new species of Sarcostemma R. Br. is described. In southern Africa there are only two species of Sarcostemma, S. viminale (L.) R. Br. and S. pearsonii N. E. Br. The former is one of the most widely distributed species in the Apocynaceae and is found from southern Africa to Australia. S. pearsonii is of more local occurrence, being endemic to South Africa and Namibia, where it is nevertheless widely distributed in arid to semi-arid areas. The new species described here occurs on the north-eastern boundary of southern Africa in the so far little-explored mountainous parts of northern Mozambique.

A phylogeny and new classification for Mesembryanthemoideae (Aizoaceae)

Guatteria (Annonaceae) is with ca. 265 species one of the largest genera of Neotropical trees together with Inga and Ocotea. Use of Guatteria in evolutionary studies has been hampered by taxonomic problems caused by lack of morphological variability in the genus. This study focuses on molecular phylogenetic relationships within Guatteria and its satellites Guatteriopsis, Guatteriella and Heteropetalum, and implications of these relationships for classification and character evolution. Results show that Guatteriopsis, Guatteriella and Heteropetalum should be merged with Guatteria. Heteropetalum may be recognized at subgeneric level because of its aberrant morphology and Guatteriopsis and Guatteriella might be given sectional status. Most of the currently recognised sections in Guatteria are probably non-monophyletic. A completely new infrageneric classification of Guatteria would be premature, however, due to the lack of molecular and morphological synapomorphies to define the sections. Synapomorphies defining Guatteria s.str. probably evolved after divergence of several early branching lineages

Phylogeny and Biogeography of the Stapeliads

The stapeliads (Apocynaceae — Asclepiadoideae — Ceropegieae) form a group of highly succulent, practically leafless plants with a very diverse floral morphology. They are found in the drier parts of the Old World from southern Africa eastwards to Burma. 55 characters are selected on which a cladistic analysis is based and these are discussed in detail where necessary. From this a phylogeny is produced for the stapeliads. It is shown that they are monophyletic and that they are nested within a larger group among the tribe Ceropegieae of the subfamily Asclepiadoideae. Several of the important innovations that have led to the diversification of the stapeliads in semidesertic regions are discussed. The stapeliads appear to be mainly fly-pollinated. The methods of attraction of flies are mentioned and it is suggested that there are four basic floral types among the stapeliads.

Recent radiation of Brachystelma and Ceropegia (Apocynaceae) across the Old World against a background of climatic change.

The genera Brachystelma Sims and Ceropegia L. of the Ceropegieae (Apocynaceae-Asclepiadoideae) consist of ±320 species of geophytes and slender climbers with a tendency to stem-succulence in Ceropegia. They occur in and around the semi-arid, mainly tropical parts of the Old World. For 146 species (around half of the total) from most of the geographic range of the genera, we analysed data from two nuclear and five plastid regions. The evolution of Ceropegia is very complex, with at least 13 mostly well-supported lineages, one of which is sister to the ±350 species of stapeliads. Species of Brachystelma have evolved at least four times, with most of them nested within two separate major lineages. So, neither Brachystelma nor Ceropegia is monophyletic. We recover a broad trend, in two separate major lineages, from slender climbers to small, geophytic herbs. Several clades are recovered in which all species possess an underground tuber. Small, erect, non-climbing, geophytic species of Ceropegia with a tuber are nested among species of Brachystelma. Consequently, the distinctive tubular flowers used to define Ceropegia do not reflect relationships. This re-iterates the great floral plasticity in the Ceropegieae, already established for the stapeliads. Both major lineages exhibit a trend from tubular flowers with faint, often fruity odours, pollinated by very small Dipteran flies, to flatter flowers often with a bad odour, pollinated by larger flies. Most of the diversity in Brachystelma and Ceropegia is recent and arose within the last 3my against a background of increased aridification or extreme climatic variability during the Pliocene. In the ingroup, diversity is highest in Southern Africa, followed by Tropical East Africa and other arid parts of Africa, the Arabian Peninsula and India. Many disjunctions are revealed and these are best explained by recent, long distance dispersal. In Africa, the diversity arises from the presence of many different lineages over wide areas but there is also evidence of closely related species growing together with different pollinators.

Evolution of the stapeliads (Apocynaceae–Asclepiadoideae) – repeated major radiation across Africa in an Old World group

The stapeliads of the Ceropegieae (Apocynaceae-Asclepiadoideae), are approximately 340 species of stem-succulents placed in around 30 genera, found in semi-arid parts of the Old World. Here we sampled 192 species (i.e. nearly two thirds of the total) from across the full geographic range of the group and analysed data from the two nuclear regions (nuclear ribosomal ITS and ncpGS) and five plastid regions (psbA-trnH intergenic spacer, rps16 intron, trnL-trnF intergenic spacer, trnS-trnG intergenic region and the non-coding rpl32-trnL region). We find that the stapeliads radiated first in the northern hemisphere from Africa to southern Europe and Myanmar. This radiation subtends a grade of minor clades in the south-western corner of the African continent. These were followed by a single clade containing major radiation back across Africa from South Africa to tropical Arabia (but no further east than Dhofar, Oman), which includes also a single early spread into Madagascar. We establish the monophyly of many of the genera, such as Echidnopsis Hook.f., Hoodia Hook., Huernia R. Br., Piaranthus R. Br., Rhytidocaulon P.R.O. Bally and Tridentea Haw., but find that Duvalia Haw., Orbea Haw., Stapelia L. and Tromotriche Haw. are polyphyletic. We show that in certain vegetative features, there is broad cohesion across clades. Florally, on the other hand, the stapeliads exhibit considerable plasticity and we are able to show that very differently shaped flowers as well as large and small flowers evolved repeatedly among closely related species.

A re-assessment of the genera Tridentea Haw. and Tromotriche Haw.

The generic delimitation of Tridentea Haw. and Tromotriche Haw. is considered, Eight species are retained in Tridentea: T. dwequensis (Luckhoff) Leach, T. gemmiflora (Masson) Haw., T. jucunda (N.E. Br.) Leach, I pachyrrhiza (Dinter) Leach, T. parvipuncta (N.E. Br.) Leach, T. marientalensis (Nel) Leach and T virescens (N.E. Br.) Leach. The remaining species are transferred to Tromotriche. Tromotriche engleriana (Schltr.) Leach is referred back to Stapelia as Stapelia engleriana Schltr. Tromotriche then consists of the following 11 species: T. aperta (Masson) Sweet, T. baylissii (Leach) Bruyns, T. choanantha (Lavranos & Hall) Bruyns, T. herrei (Net) Bruyns, T. longii (Luckhoff) Bruyns, T. longipes (Luckhoff) Bruyns, T. pedunculata (Masson) Bruyns, T. revoluta (Masson) Haw., T. ruschiana (Dinter) Bruyns, T. thudichumli (Pillans) Leach and T. umdausensis (Nel) Bruyns. Careful arguments are advanced to justify these changes.