Euphorbia Sect Research Articles

Phylogenetics and phylogeography of Euphorbia canariensis reveal an extreme Canarian-Asian disjunction but limited inter-island colonization.

Euphorbia canariensis is an iconic endemic species representative of the lowland xerophytic communities of the Canary Islands. It is widely distributed in the archipelago despite having diasporas unspecialized for long-distance dispersal. Here, we reconstructed the evolutionary history of E. canariensis at two levels: a time-calibrated phylogenetic analysis aimed at clarifying interspecific relationships and large-scale biogeographic patterns; and a phylogeographic study focused on the history of colonization across the Canary Islands. For the phylogenetic study, we sequenced the ITS region for E. canariensis and related species of Euphorbia sect. Euphorbia. For the phylogeographic study, we sequenced two cpDNA regions for 28 populations representing the distribution range of E. canariensis. The number of inter-island colonization events was explored using PAICE, a recently developed method that includes a sample size correction. Additionally, we used species distribution modelling (SDM) to evaluate environmental suitability for E. canariensis through time. Phylogenetic results supported a close relationship between E. canariensis and certain Southeast Asian species (E. epiphylloides, E. lacei, E. sessiliflora). In the Canaries, E. canariensis displayed a west-to-east colonization pattern, not conforming to the "progression rule", i.e. the concordance between phylogeographic patterns and island emergence times. We estimated between 20 and 50 inter-island colonization events, all of them in the Quaternary, and SDM suggested a late Quaternary increase in environmental suitability for E. canariensis. The extreme biogeographic disjunction between Macaronesia and Southeast Asia (ca. 11,000 km) parallels that found in a few other genera (Pinus, Dracaena). We hypothesize that these disjunctions are better explained by extinction across north Africa and southwest Asia rather than long-distance dispersal. The relatively low number of inter-island colonization events across the Canaries is congruent with the low dispersal capabilities of E. canariensis.

Meeting in Liguria: Hybridisation between Apennine endemic Euphorbia barrelieri and western Mediterranean E. nicaeensis led to the allopolyploid origin of E. ligustica

The Mediterranean Basin is renowned for its extremely rich biota and is considered as one of the 25 Global Biodiversity Hotspots, but its diversity is not homogeneously distributed. Outstanding in the number of (endemic) species are the Ligurian Alps (Italy). At the foot of the Ligurian Alps, little above the Mediterranean Sea, a disjunct occurrence of Italian endemic Euphorbia barrelieri was reported. Using an array of integrative methods ranging from cytogenetic (chromosome number and relative genome size estimation), over phylogenetic approaches (plastid, ITS and RAD sequencing) to multivariate morphometrics we disentangled the origin of these populations that were shown to be tetraploid. We performed phylogenetic analyses of the nuclear ITS and plastid regions of a broad taxonomic sampling of Euphorbia sect. Pithyusa to identify possible species involved in the origin of the tetraploid populations and then applied various analyses of RADseq data to identify the putative parental species. Our results have shown that the Ligurian populations of E. barrelieri are of allotetraploid origin that involved E. barrelieri and western Mediterranean E. nicaeensis as parental species. We thus describe a new species, E. ligustica, and hypothesise that its adaptation to similar environments in which E. barrelieri occurs, triggered development of similar morphology, whereas its genetic composition appears to be closer to that of E. nicaeensis. Our study emphasises the importance of polyploidisation for plant diversification, highlights the value of the Ligurian Alps as a hotspot of biodiversity and endemism and underlines the importance of integrative taxonomic approaches in uncovering cryptic diversity.

Widespread, but less than assumed: Populations of Euphorbia amygdaloides (Euphorbiaceae) from western Asia represent two new cryptic species

The Hyrcanian forests positioned along the southern and south-western shores of the Caspian Sea and the Euxine-Colchic forests along the southern and eastern shores of the Black Sea (western Asia) are renowned as hotspots of biodiversity and represent major refugia of Eurasian Tertiary relict forest species. One of them was considered to be Euphorbia amygdaloides (Euphorbia sect. Patellares), a forest species with wide distribution from northern Africa across Europe to western Asia. Using nuclear ribosomal ITS and plastid ndhF–trnL sequences we here show that the western Asian populations previously treated as E. amygdaloides are clearly divergent from European E. amygdaloides and actually pertain to two new species, which are also morphologically different. The newly described E. sylvicola is widespread in the Hyrcanian and Euxine-Colchic forests and is morphologically most similar to E. amygdaloides, with which it also shares its genome size. On the other hand, E. caspica is endemic to the Hyrcanian forests in Iran and is most closely related to another western Asian species, E. macroceras, with which it partly overlaps in distribution. Both species have also similar genome size, slightly lower from that of E. amygdaloides and E. sylvicola, but morphologically E. caspica resembles more E. amygdaloides than E. macroceras. Our study uncovered cryptic diversity in the forests of western Asia that had remained hidden due to slow rates of morphological evolution, i.e. morphological stasis, commonly observed in other Tertiary forest relict species, and highlights the Euxine-Colchic and especially the Hyrcanian forests as important centres of biodiversity and endemism.

A new species of succulent Euphorbia subg. Euphorbia (Euphorbiaceae) from central Somalia

A new species of Euphorbia subg. Euphorbia sect. Euphorbia is described as new to science. Euphorbia elburensis sp. nov. is endemic to central Somalia and only known from the El‐Buur area. This species belongs to a morphological group characteristic of the Horn of Africa, with tiny (2–4 mm diam.) deeply lobed capsules, well exserted on recurved pedicels, containing ovoid densely tuberculate seeds.

Euphorbia lakshminarasimhanii: a new pygmy succulent species from Konkan region of Maharashtra, India

Euphorbia lakshminarasimhanii (Euphorbiaceae), a new pygmy species belonging to the genus Euphorbia subg. Euphorbia sect. Euphorbia is described and illustrated from the Konkan region of Maharashtra, India. It is easily distinguished from all known Indian species by its unique sparsely‐branched pygmy habit, closely spaced and horizontally flattened tubercles, trapezoidal spine shields which are very close and overlapping at the apical region, giving a pouch like appearance, bifurcated spines completely separated by the leaf scar, leaves forming a crown, long bracts extending past the gland edge, coral red colored glands with indented margins, male florets 10 per fascicle, and capsule having globose cocci with thin keels.

<p><strong><em>Euphorbia sahyadrica </em></strong><strong>(Euphorbiaceae), a new species of succulent shrub from the wet zone of the northern Western Ghats, Maharashtra, India</strong></p>

Euphorbia sahyadrica (Euphorbiaceae), a new succulent species belonging to Euphorbia subg. Euphorbia sect. Euphorbia is described and illustrated from the Raigad district of Maharashtra, India. It is related to E. nivulia but differs in its shrub-like habit, bark with closely-packed horizontal branch scars, elliptical-shaped leaf with short petiole and easily visible lateral veins, protruding tubercles with two pairs of spines per spine shield, bisexual cyathia in the central sessile position on the cyme, and capsules that have laterally tapering cocci without bulging suture lines between the cocci.

<p><strong>Synopsis of <em>Euphorbia</em> section <em>Anisophyllum</em> (Euphorbiaceae) in Italy, with an insight on variation of distribution over time in Tuscany</strong></p>

We present an updated taxonomic study of Euphorbia sect. Anisophyllum (Euphorbiaceae) for Italy. A comprehensive body of knowledge has been developed thanks to the examination of about 1,250 herbarium specimens from 13 Italian herbaria, field surveys, and an extensive literature analysis. As a result, our revision included 10 species considered as currently occurring in Italy, of which 2 native (Euphorbia chamaesyce and E. peplis) and 8 alien (E. glyptosperma, E. humifusa, E. hypericifolia, E. maculata, E. nutans, E. ophthalmica, E. prostrata, and E. serpens). The revision included also additional 5 species previously erroneously recorded in Italy (E. berteroana, E. engelmannii, E. hyssopifolia, E. indica, and E. thymifolia) and other two species (E. hirta and E. humistrata) not occurring in Italy but closely related to recorded species and already established and considered as alien species in other countries. Current distribution and status at the regional level is updated for 7 species (E. berteroana, E. engelmannii, E. humifusa, E. hypericifolia, E. indica, E. nutans, and E. prostrata) and typification of 18 names (Chamaesyce glomerifera, E. boliviana, E. bracteolaris, E. brasiliensis, E. chamaesyce var. maculata, E. engelmannii, E. humifusa, E. hypericifolia var. communis, E. indica, E. klotzschiana, E. nutans, E. peplis, E. perforata, E. pinnulosa, E. preslii, E. procumbens, E. reichenbachiana, and E. trichogona) is also provided. For all taxa we report information about nomenclature, morphology, ecology, chorology, distribution, taxonomy, as well as an identification key for species identification and original photos. In addition, we provided a detailed statement of species of the section for Tuscany and we performed an analysis of distribution variation of different species over time in this region. Our results evaluate the current state of E. sect. Anisophyllum in Italy and highlight the presence of fluxes in densities of different species populations. In particular, a reduction of native and formerly colonizing species and an increase of more recently colonizing species is recorded.

Biogeography of succulent spurges from Brazilian Seasonally Dry Tropical Forest (SDTF)

AbstractSeasonally Dry Tropical Forests (SDTFs) are found scattered throughout the Neotropics, from northwestern Mexico to northern Argentina, and southwestern and eastern Brazil, with eastern Brazil having the largest and most isolated fragment of SDTF, known as Caatinga. Growing knowledge from dated phylogenies and ancestral reconstruction studies suggests that SDTF lineages are nested in geographically structured phylogenies with clades highly restricted to each disjunct patch. To address these hypotheses, we investigated the biogeographic history of Euphorbia sect. Brasilienses, a group of succulent spurges from eastern Brazil's SDTF. To this aim, we assembled a concatenated matrix from 126 accessions with four markers (302 sequences from previous studies and 19 newly generated): one nuclear (ITS1) and three plastid (matK, ndhF, trnL‐trnF) loci. Our results showed that clade Brasilienses and its sister group Stachydium diverged from a common ancestor during the Miocene around 16.5 Ma. Clade Stachydium was recovered with a mean crown age of 7.7 Ma, while clade Brasilienses was recovered as a relatively young group that started diversifying about 3.1 Ma. Biogeographic results showed that the ancestral range of the clade Stachydium + Brasilienses comprised the Andes and eastern Brazil's SDTF, therefore suggesting past connections between western and eastern South America. The ancestral range of clade Brasilienses was restricted to eastern Brazil SDTF, which contrasts with clade Stachydium, which was recovered with a broader ancestral range around Late Miocene. Our results suggest limited dispersal abilities, niche conservatisms and an origin for E. sect. Brasilienses pre‐dating the Pleistocene. By contributing to the understanding of the origin and diversification of this group of endemic spurges, our study provides insights into the history of this SDTF in eastern South America.

Euphorbia adenoplicata, a New Species of Euphorbia sect. Crossadenia from Brazil

Abstract—A new species, Euphorbia adenoplicata, is here described and illustrated. The species was found in the vicinity of Serra Geral do Tocantins, close to the border of the states of Tocantins and Bahia, within the Cerrado biome, where it grows in cerrado rupestre (rocky savannah vegetation). Euphorbia adenoplicata is placed in Euphorbia sect. Crossadenia based on morphological characters. The species is unique within the section due to its cyathial glands with the margins folded in the middle portion, splitting each gland into two cavities. We compare the morphology and ecology of E. adenoplicata with E. sarcodes and other species of E. sect. Crossadenia subsect. Ephedropeplus. Finally, we recommend that E. adenoplicata be considered critically endangered due to its extreme rarity.

Euphorbia talassica (E. sect. Esula, Euphorbiaceae), a New Species of Leafy Spurges from the Western Tian-Shan

A species of Euphorbia sect. Esula (Euphorbiaceae) from the Western Tian-Shan, Central Asia, is described as new to science. Euphorbia talassica sp. nova occurs in the Talas Mountain Range in Kazakhstan and Kyrgyzstan, and falls into E. ser. Andrachnoides because of its relatively short and broad leaves. Euphorbia talassica is most similar to E. irgisensis, from which it differs by having a slender and spreading rootstock (vs. a vertical taproot), and incrassate (vs. thin) leaves. The new species also grows at much higher elevations. Euphorbia ser. Andrachnoides is overviewed for Central Asia and adjacent areas, with seven species discussed and mapped.

New Taxa in Euphorbia (Euphorbiaceae) in Southern Africa

In preparation for a monograph of Euphorbia in southern Africa, twelve new taxa are described.In Euphorbia subsect. Medusea (Haw.) Pax & K. Hoffm. one new species, E. willowmorensis Bruyns and three new subspecies, E. arida subsp. camdebooensis Bruyns, E. friedrichiae subsp. pofadderensis Bruyns and E. multiceps subsp. tanquana Bruyns are described; two new subspecies, E. ferox subsp. calitzdorpensis Bruyns and E. pseudoglobosa subsp. vlokii Bruyns are described in Euphorbia ser. Meleuphorbia (A.Berger) Bruyns; one new subspecies, Euphorbia patula subsp. brucebayeri Bruyns is described in Euphorbia subsect. Dactylanthes (Haw.) Pax & K.Hoffm.In Euphorbia sect. Articulofruticosae Bruyns one new subspecies, E. ephedroides subsp. gamsbergensis Bruyns is described.In Euphorbia sect. Esula (Pers.) Dumort. one new species, E. corneliae Bruyns, is described from southern Namibia.In Euphorbia sect. Euphorbia there are one new species, E. otavibergensis Bruyns; one new subspecies E. subsalsa subsp. otzenii Bruyns; and one new variety, E. lydenburgensis var. minor Bruyns.In addition, in subsect. Dactylanthes the concept of Euphorbia patula Mill. is substantially re-configured and four subspecies are recognized, with E. anacantha Aiton and E. wilmaniae Marloth included as two of these subspecies.

First record of Euphorbia pedersenii Subils (Euphorbiaceae) for Brazil

We report the first record of Euphorbia pedersenii (Euphorbiaceae) for Brazil, a rare species previously known from a few localities in Argentina. The species belongs to Euphorbia sect. Nummulariopsis and is characterized by its small habit with a well-developed tuberous root system, usually linear leaves, trapezoidal cyathial glands, and pubescent ovary and fruit. In the state of Rio Grande do Sul it grows in open grasslands of the Pampa region, a phytogeographic domain severely impacted by agriculture. We provide an assessment of the conservation status and geographical distribution and habitat of E. pedersenii, along with an identification key to the species of sect. Nummulariopsis occurring in Brazil.

Une nouvelle espèce menacée de Euphorbia sect. Goniostema (Euphorbiaceae) du nord de Madagascar

Castillon, J.-P. & J.-B. Castillon (2018). A new threatened species of Euphorbia sect. Goniostema (Euphorbiaceae) from northern Madagascar. Candollea 73: 187–191. In French, English and French abstracts. DOI: http://dx.doi.org/10.15553/c2018v732a2Euphorbia longitubicinicyathium J.-P. Castillon & J.-B. Castillon (Euphorbiaceae), a new species from northeastern Madagascar is described and illustrated with field photographs. The new species belongs to Euphorbia sect. Goniostema Baill. ex Boiss. and is morphologically related to non thorny species of the east coast of Madagascar (e.g. Euphorbia geroldii Rauh, Euphorbia robivelonae Rauh or Euphorbia thuarsiana Baill.) but differs by its larger dimensions, its habit and its long trumpet shaped cyathia.

A new species and molecular phylogeny of Brazilian succulent Euphorbia sect. Brasilienses

A new species of Euphorbia sect. Brasilienses V.W. Steinm. & Dorsey is described. Euphorbia tetrangularis Hurbath & Cordeiro is endemic to the Serra de Montevidéu, a part of the Espinhaço Range located in the state of Minas Gerais, Brazil. It differs from other species within the section based on the following characters: 4-ribbed branches, green cyathia, and green cyathial glands with erect appendages. This new species would qualify as critically endangered (CR) according to IUCN criteria. An inferred phylogeny based on a combined dataset of nuclear (ITS1) and plastid regions (psbA-trnH, trnC-ycf6, matK, atpI-atpH, psbJ-petA, trnQ-rps16 × 1) confirms the monophyly of Euphorbia sect. Brasilienses and supports the recognition of E. tetrangularis. The phylogeny also suggests that this group probably underwent a recent radiation.

Seed morphology of perennial taxa of Euphorbia section Pithyusa (Euphorbiaceae) in Turkey

A comprehensive study based on seed morphology of perennial Euphorbia (Euphorbiaceae) sect. Pithyusa species occurring in Turkey is presented. A total of 14 species were studied. Seed characteristics were examined using scanning electron microscopy (SEM) as well as dissecting light microscopy. Significant features are: seed size, seed shape, shape of caruncle and seed surface ornamentation. Three different seed surface types (smooth, pitted, and wrinkled) were observed. Four main seed shapes (ovoid, oblong, quadrangular, and globose), as well as seven types of seed coat ornamentation (reticulate-areolate, areolate, alveolate, falsifoveate, pusticulate, colliculate and smooth) were found. The number of testa cells per 100 µm2 and also its range, from 8–12 to 57–63, are given.

Notes sur Euphorbia sect. Denisophorbia (Euphorbiaceae) à Madagascar: description d'une nouvelle espèce et une nouvelle synonymie

Castillon, J.-P. & J.-B. Castillon (2018). Notes on Euphorbia sect. Denisophorbia (Euphorbiaceae) in Madagascar: description of a new species and a new synonymy. Candollea 73: 19–25. In French, English and French abstracts. DOI: http//dx.doi.org/10.15553/c2018v731a3The identity of the poorly known species Euphorbia commersonii Baill. (Euphorbiaceae) is clarified. This species occurring in the Fort-Dauphin region (in the Southeast of Madagascar) is assigned to Euphorbia sect. Denisophorbia (Leandri) Croizat. Formerly considered as a later synonym of Euphorbia thuarsiana Baill., Euphorbia commersonii is reinstated and Euphorbia elliotii Leandri is considered as a later synonym. A lectotype is designated for the latter species. Euphorbia neoelliotii J.-P. Castillon & J.-B. Castillon, belonging to the same section, is described and illustrated. This new species is distinguished from Euphorbia commersonii by its more elongated and much less coriaceous leaves and its incyathescences with short green peduncles bearing a single green cyathium with tiny cyathophylls appressed to the involucre.

CAPSULE, LEAF AND CYATHIAL GLAND MORPHOLOGY OF TURKISH PERENNIAL TAXA OF Euphorbia L. SECTION Pithyusa (Raf.) Lázaro

Macro and micromorphology of cyathial glands, capsules and cauline leaf surfaces of 13 perennial species of Euphorbia L. subg. Esula Pers. sect. Pithyusa (Raf.) Lázaro in Turkey were studied. Cyathial gland structure, based on cyathial gland shapes, colour and appendages was examined from live material by direct field observations and investigations. Cauline leaves and capsule surface features were analysed with scanning electron microscopy (SEM). Capsule sizes, capsule shapes and capsule and cauline leaf surface ornamentations were also studied . The capsule shape was found to vary from subglobose to conical. In most species, cyathial gland colour ranged from greenish-yellow to yellowish-green but some species were distinguished by their reddish or purplish cyathial glands. Although the number of cyathial glands in all species was four, five cyathial glands were determined to exist in some specimens of E. pestalozzae Boiss. Three different cyathial gland shapes ( elliptic, trapezoid-elliptic or elliptic-reniform ) were observed. Capsule surface of more than half of the studied species (7 taxa) is covered with nipple-like projections (papillate-mammillate) and the rest are covered with tiny rounded or hillock-like ornamentation (colliculate). The cauline leaf surface is papillate-mammillate in the majority of the studied species, although, colliculate surface is also observed in two species ( E. seguieriana Necker and E. thessala (Form.) Degen & Dörf.). In conlusion, macro and micromorphological structures of cyathial gland and capsule of Euphorbia sect. Pithyusa taxa appeared to be useful diagnostic characters for species identifications.

Evolutionary History and Taxonomy of the Euphorbia polycarpa Complex (Euphorbia subg. Chamaesyce sect. Anisophyllum, Euphorbiaceae)

Abstract Euphorbia polycarpa (Euphorbia subg. Chamaesyce sect. Anisophyllum) is one of the most common species of the Sonoran Desert. It exhibits a wide range of morphological variation and has been considered as a taxonomic complex. Since the late nineteenth century more than seven varieties have been described for the complex, some with very restricted distributions. Because of morphological intergrades present in the complex, there has been much confusion among taxonomists, and it became necessary to clarify the taxonomy of this complex using molecular phylogenetic evidence in addition to morphology alone. In this paper we reconstruct the phylogenetic relationships for the E. polycarpa complex based on molecular information from the psbA-trnH and ITS spacers, using Bayesian inference. Morphology was compared with phylogenetic results, and we also explored geographic patterns of the varieties of the complex, as well as closely related species of Euphorbia sect. Anisophyllum. Taking into account the resu...

Phylogeography and character evolution of Euphorbia sect. Aphyllis subsect. Macaronesicae (Euphorbiaceae)

AbstractThe Macaronesian species of Euphorbia sect. Aphyllis subsect. Macaronesicae are distributed in four of the five archipelagos of Macaronesia and two mainland enclaves in Portugal and Morocco. The aims of this study are to investigate the biogeographic history of this group with AFLP and cpDNA markers, and to identify taxonomic entities within subsect. Macaronesicae based on genetic data, characterize them morphologically and infer the evolution of their diagnostic characters based on the reconstruction of ancestral character states. A continuous spatial diffusion analysis of AFLP data implicated Tenerife (central Canary Islands) as the area of origin of the group, followed by colonization of other Canarian islands and other Macaronesian archipelagos. Two dispersal events back to the mainland were also inferred. Our phylogenetic network, neighbour‐joining clustering and Structure analyses of AFLP data demonstrated that species are genetically well delimited and suggested that they may have originated from a combination of allopatric speciation at broad scales (among islands) and fine scales (within islands), or possibly sympatric ecological speciation followed by more recent inter‐island dispersal events. Ancestral character state reconstructions of morphological characters suggested that the ancestor of subsect. Macaronesicae was adapted to arid or mesic habitats, and traits associated with adaptation to humid habitats were acquired later. The central Canary Islands harbour the highest species diversity of this group in the Archipelago, and the highest nuclear and plastid genetic diversity. With regards to taxonomy, phylogenetic analyses and neighbour‐joining clustering analyses based on AFLPs showed two clearly differentiated genetic groups, sister to each other, which correspond to the E. atropurpurea and E. lamarckii complexes formerly recognised based on morphology. Euphorbia aphylla is recovered as sister to the rest of the species, supporting its exclusion from the two complexes. Euphorbia tuckeyana is excluded from the E. lamarckii complex.

Flora of Bokor National Park, Cambodia IV: A New Section and Species of Euphorbia Subgenus Euphorbia

A new section, Euphorbia sect. Bokorense under subgenus Euphorbia is established for Euphorbia bokorensis H. Toyama & Tagane, sp. nov., endemic to Bokor National Park, Cambodia. Euphorbia sect. Bokore