Fig 4 - uploaded by Thomas Haevermans
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Euphorbia rauhii. A. Habit, female plant. B. Male cyathium. C. Female cyathia. D. Fruit. E. Seed. A. McPherson & Pigeon 14909 (MO, P, TAN). B. Rauh 73956 (HEID, in spiritu). C-D. Rauh 73932 (HEID, in spiriru). E. Haevermans & Randrianjohany 67 (K, P, TAN).
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The non-succulent, leafy species of Euphorbia from Madagascar have received considerably less attention from taxonomists than the succulent Euphorbia species. The lack of a recent synthetic taxonomic treatment for this group makes it almost impossible to accurately name these species. As part of an ongoing revision of the genus in Madagascar, Eupho...
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... Acronyms follow Thiers (2021, continuously updated). Plants in the wild including all type localities were also examined following recent works on Malagasy Euphorbia (Haevermans & Labat 2004, Haevermans et al. 2009, Haevermans & Hetterscheid 2021a, 2021b. The botanical terminology follows the Kew Plant Glossary (Beentje 2016). ...
Euphorbia section Plagianthae contains only two highly distinctive accepted species of Malagasy endemic Euphorbia, restricted to the arid southern part of the island. In this paper we propose an epitype for Euphorbia plagiantha, and a lectotype for Euphorbia fiha, a name designated as a synonym of Euphorbia plagiantha. We also designate a lectotype for Euphorbia salota, and present a distribution map for the section in Madagascar.
... A revision of Euphorbia for Madagascar and surrounding islands is ongoing by TH and WH, following up on recent works on the subject (Haevermans & Labat 2004, Haevermans 2006, Haevermans et al. 2009, Haevermans & Hetterscheid 2021. All relevant names applied to these species of Euphorbia were examined. ...
... The plant also shows some variation in leaf shape, usually orbicular to obcordate (see Fig. 2BC), and pubescence (some individuals from La Table, near Tulear, show some extreme hairiness on the leaves). This variation in hairiness is also found in other members of section Pervilleanae, see Haevermans & Labat (2004) Diagnosis:-Belonging to genus Euphorbia, of unknown sectional placement, the species is most similar to the likely unrelated Euphorbia denisii, but distinguished by the following characters: leaves not peltate or subpeltate, bilobed with attenuate base (vs. subpeltate in E. denisii), fruits trilobed (vs. ...
Several species of Malagasy Euphorbia are described and compared to related species in their respective sections, along with identification keys for morphologically close relatives and distribution maps: Euphorbia agatheae, Euphorbia atimovatae, Euphorbia fuscoclada, Euphorbia graciliramulosa, Euphorbia kalambatitrensis, Euphorbia linguiformis, Euphorbia mahaboana, Euphorbia makayensis, Euphorbia multibrachiata, Euphorbia parvimedusae, Euphorbia perrierioides, Euphorbia rigidispina, Euphorbia spannringii, Euphorbia tsihombensis. New synonyms and new combinations and statuses are proposed, such as Euphorbia antsingiensis and Euphorbia crassa, and a lectotype is selected for Euphorbia rangovalensis.
... Previous phylogenetic work based on DNA sequence data suggests that the evolution of characters in Euphorbia, including growth form, photosynthetic systems, and cyathial form are highly homoplasious, and that the genus has a complex biogeographic history leading to its nearly worldwide distribution Haevermans & al., 2004;Park & Jansen, 2007;. These evolutionary and biogeographic patterns make Euphorbia an ideal system for the study of complex character evolution and adaptation of plants to different environments. ...
... Monadenium, the Madagascan species are the least understood group of species in subg. Euphorbia from a phylogenetic standpoint Haevermans & al., 2004;Park & Jansen, 2007;Zimmermann & al., 2010;. The Madagascan species include, among others, the crown-ofthorns complex (E. ...
... Boissier, 1862;Hassall, 1977), but there is ample evidence now that this previous circumscription of sect. Tirucalli does not represent a monophyletic group (Boissier, 1862;Hassall, 1977;Haevermans, 2003;Haevermans & al., 2004;Barres & al., 2011;. Also, there are a number of poorly-studied leafy species, such as E. pervilleana from Madagascar, which have been placed in sect. ...
Euphorbia subg. Euphorbia is the largest subgenus in Euphorbia and contains every growth form found across the genus. These including typical growth forms but also an array of xerophytic forms including an unusual growth form termed ???pencil-stem??? plants. These leafless, species belong to multiple clades within the subgenus. The combination of divergent and convergent evolution makes this a particularly good group in which to investigate the evolution of different growth forms. Heretofore, the composition of, and relationships among, established subclades has been unclear. In this dissertation, the largest taxonomic sample from E. subg. Euphorbia to date was compiled, and DNA sequences from one nuclear and two chloroplast regions were used to infer a phylogeny of the group. This phylogeny was then used in combination with estimates of the climatic components of species??? niches to investigate the role of abiotic ecological parameters in the repeated evolution of the pencil-stem growth form. Finally, five gene regions were used to produce the most comprehensive phylogeny to date for the largest section in the subgenus, sect. Euphorbia. This phylogeny, along with geographic distribution data and estimates of species??? ???climatic niches???, was then used to test the hypothesis that divergence of growth form within this clade is the result of an historical expansion of the group???s range from Asia into Africa, and a consequential reduction in the size of the plant body during colonization of increasingly arid habitats. I found that E.subg. Euphorbia is composed of four main clades distinguished by their geographic distribution. Further, on average, pencil-stem species in E. subg. Euphorbia occupy significantly drier sites than their leafy relatives, but this pattern may break down at the individual species level. Within E. sect. Euphorbia, the divergent evolution of growth forms is the result of adaptation to seasonal drought. Finally, current species distributions in E. sect. Euphorbia are the result of a complex pattern of range partitioning and a moderate number of dispersal events. The three chapters of this dissertation significantly improve our understanding of the phylogenetic relationships, historical biogeography, and morphological evolution of this speciose and morphologically diverse group of plants.
Genetics and chemicals relatedness among three Euphorbia species (Euphorbia prostrata Aiton, Euphorbia peplus L. and Euphorbia terracina L.) were analysed by RAPD, ISSR markers and GC-MS technique. RAPD profiling pattern revealed that E. peplus and E. terracina in one cluster with similarity value (44.37%) while the lowest value (29.14%) between E. prostrata and E. terracina. ISSR profiling pattern revealed that E. prostrata and E. terracina in one cluster with similarity value (46.75%) and the lowest similarity value (37.87%) between E. prostrata and E.peplus. The sum results of RAPD and ISSR data revealed that E. peplus and E. terracina in one cluster with similarity value (44.69%) while the lowest value (36.88%) between E. prostrata and E. peplus. Sixty-eight chemicals pattern revealed that E. prostrata and E. peplus in one cluster with similarity value (39.71%) while the lowest value (25.0%) between E. prostrata and E. terracina. Super tree (RAPD, ISSR and phytocomponents) revealed that E. peplus and E. terracina in one cluster with similarity value (43.04%) while the lowest value (36.08%) between E. terracina and E. prostrata. In conclusion, biosystematics tools including biomarkers and chemical compounds can be applied to investigate relatedness of Euphorbia species and probably to other plant taxa.
Euphorbia subg. Euphorbia is the largest and most diverse of four recently recognized subgenera within Euphorbia and is distributed across the tropics and subtropics. Relationships within this group have been difficult to discern due mainly to homoplasious morphological characters and inadequate taxon sampling in previous phylogenetic studies. Here we present a phylogenetic analysis of E. subg. Euphorbia, using one nuclear and two plastid regions, for the most complete sampling of molecular sequence data to date. We assign 661 species to the subgenus and show that it is comprised of four highly supported clades, including a single New World clade and multiple independent lineages on Madagascar. Using this phylogenetic frame-work we discuss patterns of homoplasy in morphological evolution and general patterns of biogeography. Finally, we present a new sectional classification of E. subg. Euphorbia comprising 21 sections, nine of them newly described here.
Euphorbia is among the largest genera of angiosperms, with about 2000 species that are renowned for their remarkably diverse growth forms. To clarify phylogenetic relationships in the genus, we used maximum likelihood, bayesian, and parsimony analyses of DNA sequence data from 10 markers representing all three plant genomes, averaging more than 16kbp for each accession. Taxon sampling included 176 representatives from Euphorbioideae (including 161 of Euphorbia). Analyses of these data robustly resolve a backbone topology of four major, subgeneric clades--Esula, Rhizanthium, Euphorbia, and Chamaesyce--that are successively sister lineages. Ancestral state reconstructions of six reproductive and growth form characters indicate that the earliest Euphorbia species were likely woody, non-succulent plants with helically arranged leaves and 5-glanded cyathia in terminal inflorescences. The highly modified growth forms and reproductive features in Euphorbia have independent origins within the subgeneric clades. Examples of extreme parallelism in trait evolution include at least 14 origins of xeromorphic growth forms and at least 13 origins of seed caruncles. The evolution of growth form and inflorescence position are significantly correlated, and a pathway of evolutionary transitions is supported that has implications for the evolution of Euphorbia xerophytes of large stature. Such xerophytes total more than 400 species and are dominants of vegetation types throughout much of arid Africa and Madagascar.
