Sigrid Liede-Schumann

Phylogenetics of the New World Subtribes of Asclepiadeae (Apocynaceae—Asclepiadoideae): Metastelmatinae, Oxypetalinae, and Gonolobinae

Abstract Analysis of the trnT-trnL spacer, the trnL intron, the trnL-trnF spacer, and the rps16 intron of 106 species in 34 of the 45 genera of New World Asclepiadeae in the former subtribes Metastelmatinae, Oxypetalinae, and Gonolobinae shows that these genera form a well-supported clade (“MOG”). The small Andean genus Pentacyphus is sister to the remaining MOG clade. The former Gonolobinae form a well-supported subclade closely related to members of Tassadia, Funastrum, and former Oxypetalinae. The only genera that are monophyletic as presently circumscribed are Tassadia and Funastrum. The separation of Tweedia from Oxypetalum is justified by our results. Philibertia is monophyletic only if Amblystigma, Fontellaea, Melinia, Mitostigma, and Podandra are also included. Most species of Blepharodon and Hemipogon are not monophyletic with the respective type species. Some former Astephanus and Cynanchum species as well as the monotypic Grisebachiella are imbedded in Diplolepis (D. descolei, D. geminiflora, D. hieronymi, D. boerhaviifolia, and D. nummulariifolia). The neglected tribe Orthosieae is recognized at subtribal level, Orthosiinae. Chromosome numbers (as far as known) indicate a tendency for reduction in several clades. This study provides a framework for future study of the American MOG genera and highlights areas that need further attention.

Polyphyly of Mussaenda inferred from ITS and trnT-F data and its implication for generic limits in Mussaendeae (Rubiaceae).

Although recognition of Mussaenda as a separate genus has been widely accepted, its generic circumscriptions have always been controversial. In this first molecular phylogenetic study focused specifically on Mussaenda sensu lato (s.l.) and its allied genera, parsimony analyses were based on both ITS and trnT-F sequence data to (1) test the monophyly of Mussaenda s.l. as presently circumscribed, (2) assess the phylogenetic relationships within the tribe Mussaendeae as currently delimited, (3) evaluate the phylogenetic value of the morphological characters traditionally and/or currently used to circumscribe Mussaendeae, (4) and make inferences on the biogeographical origin of Mussaenda. Of the 63 trnT-F and 38 ITS sequences included in our studies, 52 and 36 sequences, respectively, are newly published here. Our results highly support the polyphyly of Mussaenda s.l. as currently delimited but further support the monophyly of Mussaendeae sensu Bremer and Thulin. The Malagasy Mussaenda are more closely related to Landiopsis than they are to the African and Asian Mussaenda. Pseudomussaenda and the Afro-Asian Mussaenda clade are resolved as sister groups. Aphaenandra is nested within the Afro-Asian Mussaenda clade. As a result, we merge Aphaenandra in Mussaenda, which is now restricted to include only the African and Asian Mussaenda representatives. We describe a new genus Bremeria to accommodate all Indian Ocean (Madagascar and the Mascarenes) Mussaenda species and make 19 new combinations. The newly delimited Mussaenda is diagnosed by reduplicate-valvate aestivation and glabrous styles, whereas Bremeria can be distinguished from the remaining Mussaendeae genera by having both reduplicate- and induplicate-valvate aestivation and densely pubescent styles. Our studies strongly suggest an African origin of the newly delimited Mussaenda. Finally, descriptions of the newly circumscribed Mussaenda and Bremeria are provided.

Advances in apocynaceae : The enlightenment, an introduction

Abstract This issue of the Annals of the Missouri Botanical Garden is devoted to advances in the Apocynaceae s.l. and is based on the symposium, “Recent Progress in the Systematics of Apocynaceae,” held at the XVII International Botanical Congress in Vienna in 2005. The collection of papers presented here spans the phylogenetic and geographic breadth of the family and includes at least one study focused on representatives from each of the five subfamilies: Rauvolfioideae, Apocynoideae, Periplocoideae, Secamonoideae, and Asclepiadoideae. The papers range from higher-level phylogenetic analyses to more narrowly defined case studies and include new results in phylogenetics, taxonomy, biogeography, pollination biology, and a pharmacophagous plant–butterfly interaction involving pyrrolizidine alkaloids, as well as a new hypothesis for the evolution of pollinia and loss of a compitum in some advanced taxa. An updated classification scheme of the Apocynaceae is presented, with one additional tribe recognized in Rauvolfioideae (the Aspidospermeae) and three in Apocynoideae (the Nerieae and Odontadenieae as well as the Baisseeae, which are elevated in rank here). In Asclepiadoideae, seven subtribes are recognized within Asclepiadeae (the Asclepiadinae, Cynanchinae, Tylophorinae, Metastelmatinae, Orthosiinae, Oxypetalinae, and Gonolobinae) and four within Ceropegieae (the Anisotominae, Leptadeniinae, Heterostemminae, and Stapeliinae). Taken together, the papers here present the most up-to-date overview of the family available at this time.

DIVERSIFICATION OF ASCLEPIADOIDEAE (APOCYNACEAE) IN THE NEW WORLD1

Abstract Plastid sequences of trnL-F are used to estimate the age of biogeographical events in New World Asclepiadoideae. These data suggest that the subfamily arose somewhere in the Old World in the Late Eocene (40 million years ago (Ma)) and that there were at least four independent episodes of dispersal to the New World. The MOG clade, comprising Metastelmatinae, Oxypetalinae, and Gonolobinae, probably colonized South America through transoceanic dispersal from Africa at 32 Ma. The three subtribes emerged at 24 Ma, radiating 15–16 Ma. Cynanchum L. subg. Mellichampia (A. Gray) Woodson (Cynanchinae) only arrived in the New World at 24 Ma and has since diversified gradually. Asclepias L. (Asclepiadinae) probably arrived in the New World through the Bering Strait at 20 Ma, dispersing to South America before the emergence of the Isthmus of Panama. More recently, tropical Marsdenia R. Br. (Marsdenineae) probably arrived in the New World by long-distance dispersal at 16 Ma. Most diversification in New World Asclepiadoideae is estimated to have occurred during the Miocene. The synchrony of events suggests an environmental influence on the diversification of the lineages. Nevertheless, individual rates of diversification point out the importance of intrinsic factors.

Cynanchum. Rhodostegiella. Vincetoxicum. Tylophora (Asclepiadaceae) : New considerations on an old problem

On the basis of morphological and chemical data, the genus Vincetoxicum is recognized as separate from Cynanchum. Tylophora is identified as the closest relative of Vincetoxicum. In consequence, eleven new combinations in Vincetoxicum are proposed. The C. auriculatum group is recognized as C. sect. Rhodostegiella. Tylophoropsis must be included in Tylophora, which results in one new combination.

CEROPEGIA (APOCYNACEAE, CEROPEGIEAE, STAPELIINAE): PARAPHYLETIC BUT STILL TAXONOMICALLY SOUND1

Abstract Even though the species-rich genus Ceropegia L. (Apocynaceae, Ceropegieae) is convincingly characterized by its pitfall flowers, investigation of non-coding markers of chloroplast DNA (cpDNA) (trnT-L and trnL-F spacers and the trnL intron) and nuclear ribosomal DNA (nrDNA) (ITS) has shown that Ceropegia is twice paraphyletic. The 36 analyzed Ceropegia taxa scatter over a grade of seven clades. One clade is shared by Ceropegia and all Brachystelma R. Br. species investigated, making Ceropegia (without Brachystelma) paraphyletic. All endemic Madagascan Ceropegia taxa investigated and the East African C. robynsiana Werderm. share a terminal, but not further-resolved clade with the stapeliads. Thus, again, Ceropegia without the stapeliads is paraphyletic. These results are incongruent with current taxonomy. In the absence of adequate morphological, anatomical, or karyological characters supporting a taxonomic reclassification of the genus in accordance with the retrieved clades of the phylogenetic analysis, it is proposed that the current taxonomy be maintained.

Phylogenetic analysis of Sesuvioideae (Aizoaceae) inferred from nrDNA internal transcribed spacer (ITS) sequences and morphological data

The phylogeny of the four genera of Aizoaceae subfamily Sesuvioideae (Sesuvium, Cypselea, Trianthema and Zaleya) is elucidated employing internal transcribed spacer (ITS) sequences and 23 morphological characters. Phylogenetic analysis based on ITS sequences and a combined molecular-morphological analysis provide largely congruent results. The monophyly of Sesuvioideae and its close relationship to Aizooideae s.l. and Mesembryanthemoideae is confirmed. Zaleya is placed within Trianthema and Cypselea within Sesuvium by ITS analysis, but in the combined analysis, Zaleya forms an unresolved polytomy with the two Trianthema clades and Cypselea, as well as two Sesuvium species, remain unresolved. Sesuvium sesuvioides and S. hydaspicum, previously treated as synonyms, are closely related, but molecular data do not support conspecifity. The Trianthema triquetra complex needs further intensive study because the African T. triquetra sample is closer to the NE African-Arabian T. sheilae than to Australian samples of T. triquetra. The close relationship of four species of Trianthema (T. patellitecta, T. rhynchocalyptra, T. megasperma, and T. pilosa) from Australia based on molecular data is supported morphologically by the exclusive possession of a well-developed indumentum in these taxa.

Phylogenetic relationships in subtribe asclepiadinae (Apocynaceae: Asclepiadoideae)

Abstract A first approximation of evolutionary relationships within the Asclepiadinae (Apocynaceae: Asclepiadoideae) is inferred from two DNA data sets, from the nuclear ITS region, and from plastid trnT-L and trnL-F spacers and trnL intron. Both the subtribe as a whole and the phylogenetic radiation of largely herbaceous genera around Asclepias are monophyletic and well supported. While resolution within the Asclepias complex is limited, the lineages identified demonstrate that current generic delimitation is unsatisfactory. Asclepias should be either restricted to New World members of the subtribe or expanded to encompass the entire radiation. In the African species, it is shown that, although the corona is taxonomically important for recognizing species, it can be misleading as an indicator of phylogenetic relationship. Vegetative similarities often prove a more reliable guide, but more detailed studies are needed to refine these lineages and to detect morphological characters to aid in their practical recognition.

Taxonomic Considerations on Metastelmatinae (Apocynaceae) Based on Plastid and Nuclear DNA

Abstract The Metastelmatinae (Asclepiadoideae, Apocynaceae) include 13 genera and approximately 260 species with complex morphological affinities that are broadly distributed in the Neotropics. This study investigated phylogenetic relationships within this subtribe using plastid (trnT-F, trnS-G, trnH-psbA, trnD-T, rps16, and matK) and nuclear (ITS) markers. The taxonomic sampling focused on the South American species, and included approximately 25% of the subtribe. Individual data partitions, and combined datasets were analyzed using Bayesian inference, maximum likelihood, and maximum parsimony. The results indicated that most genera of Metastelmatinae are not monophyletic. Internal relationships in the subtribe and key morphological characters used in the taxonomy of the group are discussed. The lack of resolution in the molecular phylogeny, incongruent phylogenetic signals between plastid and nuclear datasets, and the lack of morphological features for individual clades prevented major taxonomic changes in this group, those of which were restricted to the inclusion of Barjonia harleyi and Hemipogon harleyi into Minaria forming the new combinations Minaria harleyi and M. volubilis , and the synonymy of Macroditassa under Peplonia with the new combinations Peplonia adnata and P. macrophylla .

Taxonomy of Peplonia (including Gonioanthela ) and a reinterpretation of Orthosieae (Asclepiadoideae, Apocynaceae)

In many cases phylogenetic studies based on molecular data have led to changes in the classification of the Asclepiadoideae, but in others they have corroborated relationships previously inferred from morphological data. This study combines results of molecular analysis and morphology to provide a new subtribal classification for the New World genera Gonioanthela, Jobinia, Macroditassa, Peplonia and Orthosia. Our data allow us to propose the inclusion of Gonioanthela in the formerly monotypic Peplonia. This inclusion leads