On the systematic position of some Asian enigmatic genera of Asclepiadoideae (Apocynaceae)

The phylogenetic structure of Asclepiadoideae (Apocynaceae) has been elucidated at the tribal and subtribal levels in the last two decades. However, to date, the systematic positions of seven Asian genera, Cosmostigma, Graphistemma, Holostemma, Pentasachme, Raphistemma, Seshagiria and Treutlera, have not been investigated. In this study, we examine the evolutionary relationships among these seven small enigmatic Asian genera and clarify their positions in Asclepiadoideae, using a combination of plastid sequences of rbcL, rps16, trnL and trnL‐ F regions. Cosmostigma and Treutlera are resolved as members of the non‐Hoya clade of Marsdenieae with strong support (maximum parsimony bootstrap support value BS_MP = 96, maximum likelihood bootstrap support value BS_ML = 98, Bayesian‐inferred posterior probability PP = 1.0). Pentasachme is resolved as sister of Stapeliinae to Ceropegieae with moderate support (BS_MP = 64, BS_ML = 66, PP = 0.94). Graphistemma, Holostemma, Raphistemma and Seshagiria are all nested in the Asclepiadeae–Cynanchinae clade (BS_MP = 97, BS_ML = 100, PP = 1.0). The study confirms the generally accepted tribal and subtribal structure of the subfamily. One exception is Eustegia minuta, which is placed here as sister to all Asclepiadeae (BS_MP = 58, BS_ML = 76, PP = 0.99) and not as sister to the Marsdenieae + Ceropegieae clade. The weak support and conflicting position indicate the need for a placement of Eustegia as an independent tribe. In Asclepiadeae, a sister group position of Cynanchinae to the Asclepiadinae + Tylophorinae clade is favoured (BS_MP = 84, BS_ML = 88, PP = 1.0), whereas Schizostephanus is retrieved as unresolved. Oxystelma appears as an early‐branching member of Asclepiadinae with weak support (BS_MP = 52, BS_ML = 74, PP = 0.69). Calciphila and Solenostemma are also associated with Asclepiadinae with weak support (BS_MP = 37, BS_ML = 45, PP = 0.79), but all alternative positions are essentially without support. The position of Indian Asclepiadoideae in the family phylogeny is discussed. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 601–619.     

Heterostemma trilobatum sp. nov. (Apocynaceae: Asclepiadoideae) from Thailand

A new species, Heterostemma trilobatum A. Kidyoo & Thaithong has been discovered in northern, northeastern and southeastern Thailand. It is here described, illustrated and meticulously compared with a morphologically similar species, H. xuansonense T. B. Tran & J. Hw. Kim. Both species resemble each other, having sessile to subsessile cymes, five glands on the inside of the calyx and dark red to purplish red ovate corona lobes. However, H.trilobatum is markedly differentiated by much smaller size of flowers and the presence of peculiar trilobed corona appendages.     

A systematic revision of Anechites (Apocynaceae)

Anechites Grisebach is a rarely collected genus of Apocynaceae indigenous to the Caribbean, Central America, and coastal northern South America. It is infrequent where it occurs and has a problematic taxonomic history. The genus is described and illustrated, its important morphological characters, history, and relationships are discussed, and a distribution map is provided.     

老鸦瓣属(百合科)的恢复: 以形态性状的分支分析为依据

老鸦瓣群(Amana群)是百合科中的一个东亚特有类群,仅分布在中国中东部、日本和朝鲜半岛。该类群在形态上与广义郁金香属Tulipa L.相似,但也具有与子房近等长的花柱以及2-3(-4)个苞片等与郁金香属不同的形态特征。有关该类群是否应置于郁金香属中或是否应独立为属的问题长期以来存在争议。为了澄清该问题,我们对产于中国的Amana群进行了广泛的标本室和野外形态观察,并采用分支系统学方法,对该类群3个种以及郁金香属的其他15种植物(包括土耳其的3个种)的28个形态性状数据进行了分支分析。结果表明广义郁金香属并非是一个单系类群。Amana群与广义郁金香属的其他4个组sect. Orithyia、sect. Eriostemones、sect. Leiostemones、sect. Tulipanum以及Lloydia属的两个种共同构成一个大支的3个分支。我们对广义郁金香属5个组共19种植物的ITS以及trnL-F分子序列综合分析的结果也表明：sect. Tulipanum、sect. Leiostemones、sect. Eriostemones和sect. Orithyia构成一大支,Amana群和猪牙花属的Erythronium sibiricum构成另一大支。因此,我们认为Amana群应从广义郁金香属中独立出来,恢复其老鸦瓣属Amana Honda作为属的分类地位。     

Caralluma bicolor sp. nov. (Apocynaceae,Asclepiadoideae) from India

Caralluma bicolor Ramach, S. Joseph, H. A. John & C. Sofiya sp. nov. (Apocynaceae) collected from Coimbatore, Tamil Nadu in India is described and illustrated. Morphological differences between the new species and the allied species C. adscendens (Roxb.) Haw. and C. sarkariae Lavranos & Frandsen are discussed.     

Molecular phylogeny of Ceropegia (Asclepiadoideae, Apocynaceae) from Indian Western Ghats

Ceropegia includes more than 200 species distributed in the Old World ranging from the Canary Islands to Australia. In India, there are about 50 species described on a morphological basis as belonging to Ceropegia, and most of them are endemic to the Western Ghats. To investigate evolutionary relationships among Indian Ceropegia taxa and their allies, a phylogenetic analysis was conducted to include 31 Indian taxa of Ceropegia and Brachystelma and their congeners from other geographical regions using nuclear ribosomal internal transcribed spacer (ITS) and three noncoding chloroplast DNA (cpDNA) sequences, including intergenic spacers trnT-L and trnL-F, and trnL intron. The Western Ghats Ceropegia species were found to be most closely related to Indian Brachystelma, with the two genera being placed sister to each other in the ITS phylogeny or with the Brachystelma clade nested within one of the two subclades of Indian Ceropegia in the cpDNA phylogeny. In contrast, Ceropegia species from other regions and African Brachystelma all formed separate clades basal to the Indian Ceropegia–Brachystelma clade. Thus, it can be concluded that the classical morphology-based delineation of the two genera needs revision to reflect their phylogenetic relationships, which are more in accordance with their geographical origin than with morphology.     

Ceropegia pullaiahii sp. nov. (Apocynaceae,Asclepiadoideae) from India

Ceropegia pullaiahii Kullayiswamy, Sandhyarani et Karuppusamy sp. nov. (Apocynaceae) is described from open dry deciduous forest of Anantapur district, Andhra Pradesh, India. Its tubers are eaten by the local people. It is similar to C. mahabalei Hemadri et Ansari but differs in its twining habit and 3‐flowered cyme.     

Dischidia kerrii sp. nov. (Apocynaceae: Asclepiadoideae) from northeastern Thailand

Dischidia kerrii is presented as a new species from northeastern Thailand. This newly discovered species is thoroughly described, discussed and illustrated. A comparison is made with the putative closely related species D. acuminata. They can be distinguished by differences in corolla lobes and staminal corona lobes.     

Fly pollination in Ceropegia (Apocynaceae: Asclepiadoideae): biogeographic and phylogenetic perspectives

Background and Aims

Ceropegia (Apocynaceae subfamily Asclepiadoideae) is a large, Old World genus of >180 species, all of which possess distinctive flask-shaped flowers that temporarily trap pollinators. The taxonomic diversity of pollinators, biogeographic and phylogenetic patterns of pollinator exploitation, and the level of specificity of interactions were assessed in order to begin to understand the role of pollinators in promoting diversification within the genus.

Methods

Flower visitor and pollinator data for approx. 60 Ceropegia taxa were analysed with reference to the main centres of diversity of the genus and to a cpDNA–nrDNA molecular phylogeny of the genus.

Key Results

Ceropegia spp. interact with flower-visiting Diptera from at least 26 genera in 20 families, of which 11 genera and 11 families are pollinators. Size range of flies was 0·5–4·0 mm and approx. 94 % were females. Ceropegia from particular regions do not use specific fly genera or families, though Arabian Peninsula species are pollinated by a wider range of Diptera families than those in other regions. The basal-most clade interacts with the highest diversity of Diptera families and genera, largely due to one hyper-generalist taxon, C. aristolochioides subsp. deflersiana. Species in the more-derived clades interact with a smaller diversity of Diptera. Approximately 60 % of taxa are so far recorded as interacting with only a single genus of pollinators, the remaining 40 % being less conservative in their interactions. Ceropegia spp. can therefore be ecological specialists or generalists.

Conclusions

The genus Ceropegia has largely radiated without evolutionary shifts in pollinator functional specialization, maintaining its interactions with small Diptera. Intriguing biogeographic and phylogenetic patterns may reflect processes of regional dispersal, diversification and subsequent specialization onto a narrower range of pollinators, though some of the findings may be caused by inconsistent sampling. Comparisons are made with other plant genera in the Aristolochiaceae and Araceae that have evolved flask-shaped flowers that trap female flies seeking oviposition sites.Key words: Apocynaceae, Asclepiadoideae, Brachystelma, Ceropegia, Diptera, flower evolution, generalization, mutualism, pollination, Riocreuxia, specialization, Stapeliinae     

Hoya hanhiae sp. nov. (Apocynaceae,Asclepiadoideae) from central Vietnam

A new species, Hoya hanhiae V. T. Pham et Aver. discovered in central Vietnam is described, illustrated and compared with the related species H. macrophylla Bl. and H. verticillata (Vahl) G. Don.     

The systematic position of theHolarrheninae (Apocynaceae)

The genusHolarrhena, described byRobert Brown in 1811, has had a problematic taxonomic history, in part due to a suite of characters that does not conform with accepted concepts within theApocynaceae. In a number of important taxonomic charactersHolarrhena is typical of subfam.Apocynoideae. But due to the relatively unspecialized structure of the anthers most recent authors have placedHolarrheng, together withCarruthersia andSpirolobium, as the subtribeHolarrheninae in subfam.Plumerioideae. For the present investigation the floral structure and pollen morphology ofHolarrhena, Carruthersia andSpirolobium were analyzed. From the chemical literature reports of the occurrence of steroidal alkaloids in thePlumerioideae were evaluated. Our results indicate that the three genera belong to subfam.Apocynoideae in the tribeNerieae, but that the Holarrheninae is an unnatural group, and that the three genera should be accommodated individually within the tribe.     

Comparative vegetative anatomy and classification of Diseae (Orchidaceae)

The leaf, stem, root, tuber and dropper anatomy of the orchid tribe Diseae (including the subtribes Satyriinae, Disinae, Brownlecinac, Huttonaeinae and Coryciinae) is reviewed. The study is largely based on investigations of 123 species, and data from several previous publications have also been incorporated. Two characters were identified as being taxonomically valuable: (1) the presence of sclerenchyma caps associated with leaf vascular bundles, and (2) the degree of dissection of the siphonostele of the tuber ('polystelic' or 'monostelic'). The phylogenetic analysis shows that anatomical characters do not change the basic structure of a cladogram that is based on morphological characters. The taxa of Diseae are discussed on the basis of anatomical data. Subtribes Satyriinae (excluding the anatomically unusual genus Pachites), Brownleeinae, Huttonaeinae, and Coryciinae are uniform in. critical anatomical characters. However, subtribe Disinae is rather diverse in vegetative anatomy. Disa sect. Micranthae differs from the rest of the genus in its leaf anatomy. The occurrence of foliar sclerenchyma bundle caps and 'polystelic' tubers supports the incorporation of Herschelianthe in Disa sect. Stenocarpa.     

Comparative vegetative anatomy and classification of Diseae (Orchidaceae)

The leaf, stem, root, tuber and dropper anatomy of the orchid tribe Diseae (including the subtribes Satyriinae, Disinae, Brownlecinac, Huttonaeinae and Coryciinae) is reviewed. The study is largely based on investigations of 123 species, and data from several previous publications have also been incorporated. Two characters were identified as being taxonomically valuable: (1) the presence of sclerenchyma caps associated with leaf vascular bundles, and (2) the degree of dissection of the siphonostele of the tuber (‘polystelic’ or ‘monostelic’). The phylogenetic analysis shows that anatomical characters do not change the basic structure of a cladogram that is based on morphological characters. The taxa of Diseae are discussed on the basis of anatomical data. Subtribes Satyriinae (excluding the anatomically unusual genus Pachites), Brownleeinae, Huttonaeinae, and Coryciinae are uniform in. critical anatomical characters. However, subtribe Disinae is rather diverse in vegetative anatomy. Disa sect. Micranthae differs from the rest of the genus in its leaf anatomy. The occurrence of foliar sclerenchyma bundle caps and ‘polystelic’ tubers supports the incorporation of Herschelianthe in Disa sect. Stenocarpa.     

A synopsis of <Emphasis Type="Italic">Asclepias</Emphasis> (Apocynaceae: Asclepiadoideae) in tropical Africa

In preparation for two major regional Flora accounts, Asclepias has been reassessed in tropical Africa. 38 species not assigned to the allied genera Aspidoglossum, Glossostelma, Gomphocarpus, Margaretta, Pachycarpus, Stathmostelma, Stenostelma or Xysmalobium are recognised in the region. Nine species and one subspecies are described for the first time. The inclusion of Trachycalymma again within Asclepias requires four new combinations. A further three new names or combinations are required for the transfer of Odontostelma welwitschii, Schizoglossum alpestre and Stathmostelma verdickii to Asclepias. Five names are lectotypified, and a neotype proposed for Gomphocarpus meliodorus. The conservation status of all species is assessed.