Astragalus mario-sousae (Fabaceae: Galegeae), a new species from northeastern Mexico

Astragalus mario-sousae is described from the central part of state of Nuevo León, Mexico. It differs fromAstragalus esperanzae by its habit, peduncles, pedicels, and fruits.

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Resumen   Astragalus mario-sousae (Fabaceae: Galegeae), a new species from northeastern Mexico. Brittonia 57: 314–319. 2005.—Astragalus mario-sousae es propuesta como especie nueva. Se conoce solo de la porción central del estado mexicano de Nuevo León. Se presentan una descripción e ilustración. Difiere deAstragalus esperanzae por su hábito erecto, pedúnculos, pedicelos y frutos más cortos.

     

Ecology of two geographically restricted Astragalus species (Fabaceae), A. bibullatus and A. tennesseensis, of the eastern United States

Astragalus bibullatus is endemic to limestone glades in the Central Basin of Tennessee, and except for one population in Illinois,A. tennesseensis is endemic to limestone glades in the Central Basin and in the Moulton Valley of Alabama. However,A. tennesseensis has been extirpated from four counties in Illinois, from its only known site in Indiana, from one county in Tennessee, and from one county in Alabama.Astragalus bibullatus is closely related to the geographically wide-spread Great Plains taxonA. crassicarpus var.crassicarpus (sectionSarcocarpi), whereasA tennesseensis is the only taxon in sectionTennesseensis. Both species are shallow-rooted, hemicryptophyte perennials without vegetative reproduction, have no effective means of seed dispersal, form long-lived seed banks, have similar life cycle phenologies, are intolerant of heavy shade, and have moderate amounts of genetic diversity. Much. additional information is available on the autecology ofA. tennesseensis. Its primary habitat is the transition zone between open glades and glade woods, where physical environmental factors are intermediate between those of the adjacent zones. Seedling-juvenile survival is low. Plants flower first in their second to fifth year and only a few times before dying, are self-incompatible, respond to drought by shedding leaves and by accumulating large amounts of proline, and compete poorly. Populations exhibit high fluctuations in number of individuals and have high turnover rates. A greenhouse study ofA bibullatus andA crassicarpus var.crassicarpus did not identify any difference in responses of these species to light or soil moisture that could account for the great differences in geographic ranges. Thus, historical factors were also considered to explain the narrow endemism ofA. bibullatus. Finally, we present previously unpublished data on the effect of light level and of competition with the cedar glade dominantSporobolus vaginiflorus in several watering regimes on growth ofA. tennesseensis. The role of these factors in restriction of this species to its transition zone microhabitat is discussed.     

Molecular systematics of the Old World Astragalus (Fabaceae) as inferred from nrDNA ITS sequence data

This study represents a nuclear rDNA ITS-based phylogenetic analyses of a greater sampling of the Old WorldAstragalus compared to our previous work (212 vs. 134 taxa). Phylogenetic relationships among 212 species (213 accessions) of the Old WorldAstragalus, including newly segregated monotypic genusPodlechiella, the two aneuploid New WorldAstragalus, and five related genera, were inferred from analyses of nuclear rDNA ITS sequences using maximum parsimony. A total of 658 nucleotide sites and four binary characters for indels were analyzed. The results of phylogenetic analyses suggest sect.Phyllolobium, comprising mostly the Chinese species, is placed outside of the so-calledAstragalus s. str. and is a well-supported monophyletic group. The monotypic annual segregate genusThlaspidium (≡Astragalus sect.Thlaspidium, A. thlaspi), is clearly nested withinAstragalus s. str. Among the many sections analyzed here, only sects.Cenanthrum, Caraganella, Eremophysa, Incani, Laxiflori, andLotidium are strongly supported as monophyletic. Our analysis, in agreement with previous studies, shows that the North American euploidAstragalus species are scattered throughout the Old World groups of the genus.     

Evidence of population bottleneck in Astragalus michauxii (Fabaceae), a narrow endemic of the southeastern United States

Genetic factors such as decreased genetic diversity and increased homozygosity can have detrimental effects on rare species, and may ultimately limit potential adaptation and exacerbate population declines. The Gulf and Atlantic Coastal Plain physiographic region has the second highest level of endemism in the continental USA, but habitat fragmentation and land use changes have resulted in catastrophic population declines for many species. Astragalus michauxii (Fabaceae) is an herbaceous plant endemic to the region that is considered vulnerable to extinction, with populations generally consisting of fewer than 20 individuals. We developed eight polymorphic microsatellites and genotyped 355 individuals from 24 populations. We characterized the population genetic diversity and structure, tested for evidence of past bottlenecks, and identified evidence of contemporary gene flow between populations. The mean ratios of the number of alleles to the allelic range (M ratio) across loci for A. michauxii populations were well below the threshold of 0.68 identified as indicative of a past genetic bottleneck. Genetic diversity estimates were similar across regions and populations, and comparable to other long-lived perennial species. Within-population genetic variation accounted for 92 % of the total genetic variation found in the species. Finally, there is evidence for contemporary gene flow among the populations in North Carolina. Although genetic factors can threaten rare species, maintaining habitats through prescribed burning, in concert with other interventions such as population augmentation or (re)introduction, are likely most critical to the long term survival of A. michauxii.     

Aspalathus abbottii (Fabaceae: Crotalarieae), a new species from KwaZulu-Natal, South Africa

A new species Aspalathus abbottii C.H. Stirt. & Muasya, is described. The species is known only from Oribi Flats, KwaZulu-Natal, where it grows in grassland vegetation. The new species is characterised by its rigid spreading habit, densely and shortly villous branches, glabrous bracts and bracteoles, and 1(2) bright yellow flowers borne on short lateral shoots. It is most similar to other grassland species, A. frankenioides DC. and A. gerrardii H. Bol., all from the summer rainfall area of South Africa but differs in its rigid spreading habit, few bright yellow flowers per flowering branchlet, glabrous bracts and bracteoles, villous yellowish-green seasonal shoots, and its pale brown to tan over-seasonal branches with a blackish lattice of peeled bark.     

Molecular systematics of the genus Astragalus L. (Fabaceae): Phylogenetic analyses of nuclear ribosomal DNA internal transcribed spacers and chloroplast gene ndhF sequences

Comparative sequencing of internal transcribed spacers (ITS) and 5.8S gene of nuclear ribosomal DNA was carried out to examine phylogenetic relationships among subgenera and sections of Old World Astragalus as well as the recent segregate genera Barnebyella and Ophiocarpus. For a subset of these taxa (43 accessions), the nrDNA ITS data were supplemented by sequences from the chloroplast ndhF gene. Phylogenetic trees resulting from separate analyses of the nrDNA ITS and ndhF sequences were in conflict mainly on the position and relationships of Ophiocarpus aitchisonii, Astragalus hemsleyi, A. grammocalyx, A. coelicolor, A. capito, A. epiglottis and A. annularis. Excluding these taxa, phylogenetic analysis of a combined nrDNA ITS-ndhF data matrix was also conducted, so that in the resulting tree, most clades were more resolved and better statistically supported than those were in the separate analyses. Our results indicate that the monotypic segregate genera Barnebyella (= A. migpo), Ophiocarpus (= A. ophiocarpus) and morphologically isolated annual species A. dipelta (= Didymopelta turkestanica), A. schmalhausenii (= Sewerzowia turkestanica) and A. vicarius (= S. vicaria) are clearly nested within Astragalus. Our results confirm earlier studies that shows A. vogelii is allied with the genera Colutea and Oxytropis rather than with any Astragalus species. It is therefore excluded from Astragalus and elevated to the new generic rank and named as Podlechiella Maassoumi and Kazempour Osaloo. None of the eight traditionally recognized Astragalus subgenera Epiglottis, Trimeniaeus, Phaca, Hypoglottis, Calycophysa, Tragacantha, Cercidothrix and Calycocystis are monophyletic. Similarly, the monophyly of Podlechs new subgenera Trimeniaeus, Astragalus and Cercidothrix is not supported. Among the many species-rich sections analyzed here, only Cenanthrum, Chronopus, Laxiflori, Lotidium, Incani and Amodendron are monophyletic.     

Analysis of intraspecific seed diversity in Astragalus aquilanus (Fabaceae), an endemic species of Central Apennine

• This work aims to study seeds of the endemic species Astragalus aquilanus from four different populations of central Italy. We investigated seed morpho‐colorimetric features (shape and size) and chemical differences (through infrared spectroscopy) among populations and between dark and light seeds.
• Seed morpho‐colorimetric quantitative variables, describing shape, size and colour traits, were measured using image analysis techniques. Fourier transform infrared (FT‐IR) spectroscopy was used to attempt seed chemical characterisation. The measured data were analysed by step‐wise linear discriminant analysis (LDA). Moreover, we analysed the correlation between the four most important traits and six climatic variables extracted from WorldClim 2.0.
• The LDA on seeds traits shows clear differentiation of the four populations, which can be attributed to different chemical composition, as confirmed by Wilk's lambda test (P < 0.001). A strong correlation between morphometric traits and temperature (annual mean temperature, mean temperature of the warmest and coolest quarter), colorimetric traits and precipitation (annual precipitation, precipitation of wettest and driest quarter) was observed.
• The characterisation of A. aquilanus seeds shows large intraspecific plasticity both in morpho‐colorimetric and chemical composition. These results confirm the strong relationship between the type of seed produced and the climatic variables.

     

Conservation genetics of Amorpha georgiana (Fabaceae), an endangered legume of the Southeastern United States

Amorpha georgiana (Fabaceae) is an endangered legume species found in longleaf pine savannas in the Southeastern United States. Approximately 900 individuals and 14 populations remain, most of which are concentrated in North Carolina. Eleven microsatellite loci were used to explore genetic diversity, population structure and recent population bottlenecks using genotypic data from 132 individuals collected at ten different localities. Although A. georgiana is quite rare, it exhibited high levels of genetic diversity (17.7 alleles/locus; H _o = 0.65, H _E = 0.75). Most of the genetic variation was found within rather than between populations of this species. The single remaining Georgia population was well differentiated from populations of the Carolinas ( F _ST > 0.1), which had weaker structure among them ( F _ST < 0.1). Only a geographically disjunct population showed strong evidence of a recent population bottleneck, perhaps due to a recent founder event. Hybridization with A. herbacea was also detected. For conservation management plans, A. georgiana populations in each geographic region (North Carolina, South Carolina and Georgia) plus a disjunct population in North Carolina (Holly Shelter) should be treated as separate management units for which in situ conservation, including habitat restoration and use of prescribed burns, should ensure persistence of this species and preservation of its evolutionary potential.     

Phylogenetics of New World Astragalus: Screening of novel nuclear loci for the reconstruction of phylogenies at low taxonomic levels

This study explores methods to use information gathered from genomics technology to understand evolutionary relationships in the hyperdiverse legume group Neo-Astragalus. These species inhabit deserts and mountains of North and South America, and even though the monophyly of the group is well established, relationships within it are still poorly understood. Plastid genes, commonly used to infer phylogenies in plants, are usually not useful for closely related taxa because of low levels of genetic variation. TheMedicago truncatula genome project provided a suite of candidate nuclear loci with high levels of variation that might prove suitable for low-level phylogenetics. This paper reports the development of methods for screening a large number of these nuclear loci, and detailed analysis of four of them. Four different patterns of phylogenetic diversification occur in the loci sampled from these genomes ofAstragalus species. One locus (CNGC4) was single copy and could be directly used in phylogenetic analyses. Two loci (ARG10 and FENR) showed patterns strongly suggestive of duplication events in some taxa, and one locus (tRALS) has apparently undergone a cryptic duplication, making it very difficult to diagnose. Potential methods for using the information provided by these loci are discussed.     

Study of pollen brush in selected species of Astragalus L. subgenus Pogonophace Bunge (Leguminosae)

Nine species of Lippia (Verbenaceae) were studied by RAPD markers in order to evaluate the degree of genetic diversity. The following species were collected at the Cadeia do Espinhaço Mountains, Southeast Brazil: L. corymbosa, L. diamantinensis, L. filifolia, L. florida, L. hermannioides, L. lupulina, L. rotundifolia, L. rosella and L. sidoides. The analysis was performed using 18 primers that generated 490 fragments and only one primer was found to be monomorphic in all individuals. The average interspecific genetic distances were similar for all species and higher than the intraspecific genetic distances. Species with narrow occurrence did not show low intraspecific diversity. The molecular data were used to generate an UPGMA dendrogram that showed two major groups with a clear distribution among the species. RAPD analysis was efficient to address the genetic diversity of Lippia species and contributed to understand the adaptation to the environment, conservation and taxonomic implications.     

中国西南地区特有水生植物海菜花微卫星引物开发

水鳖科(Hydrocharitaceae)海菜花(Ottelia acuminata)是中国西南地区特有的水生单子叶植物。基于AFLP技术的磁珠富集快速分离技术(Fast Isolation by AFLP of Sequences Containing Repeats,FIASCO),共筛选出9对多态性引物并对3个居群45个个体进行分析。结果表明:三个居群的等位基因数目为1~3个,观测杂合度从0.000~0.933,期望杂合度从0.000~0.605。这些筛选出的微卫星引物将用于海菜花后续的谱系地理学和生态遗传学研究。     

Molecular phylogeny of Old WorldTrifolium (Fabaceae), based on plastid and nuclear markers

Phylogenies of Old WorldTrifolium species were constructed using nucleotide sequence data of the internal transcribed spacers (ITS) of nuclear ribosomal DNA and chloroplast DNA restriction site data from PCR-amplified genes and genic regions (rbcL,trnK, andrpoC1–C2). Biogeography, morphological evolution, and the existing classification forTrifolium were examined. The genusTrifolium is strongly supported as monophyletic, however, only one small section (Chronosemium) is monophyletic, although the data are in conflict regarding its placement. The two largest sections of the genus, Sects.Lotoidea andTrifolium, are not supported as monophyletic, as currently circumscribed. Many members of Sect.Lotoidea are basal within the genus, supporting previously-proposed hypotheses concerning plesiomorphic morphological characters and a Mediterranean-Mideast biogeographic origin of the genus.     

Bobgunnia, a new African genus of tribe Swartzieae (Fabaceae, Faboideae)

A new genus, Bobgunnia, is established in tribe Swartzieae for the African species of Swartzia. Two new combinations are made: B. fistuloides and B. madagascariensis. The new genus has seeds, unlike the remainder of tribe Swartzieae but like the other tribes of Faboideae. The systematic position of Swartzieae is reevaluated.     

无量山石豆兰, 中国兰科植物一新记录种

报道了中国兰科植物一新记录种,即无量山石豆兰(Bulbophyllum pinicola)。对其进行了特征描述并与相似种Bulbophyllum acutiflorum做了对比,并提供了彩色照片。无量山石豆兰的萼片披针形,先端渐尖,花瓣三角状披针形,先端渐尖,唇瓣稍向外下弯而易与相似种区分。