首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
The cladistic relationships of endemic Commidendrum (four species) and Melanodendron (one species) from St Helena were inferred from sequences of ITS1 and ITS2 of nuclear ribosomal DNA. Despite showing a range of morphological and ecological variation, the four species of Commidendrum , C. spurium , C. robustum , C. rotundifolium , and C. rugosum , form a closely related monophyletic group with percentage sequence divergence between 0.2 and 0.9%. Melanodendron integrifolium is sister to Commidendrum indicating that the two genera may have evolved from a common ancestor that arrived in St Helena via a single dispersal event. The closest relatives of Commidendrum and Melanodendron appear to be South African, in the predominantly shrubby genus Felicia , although further sampling of South African Astereae is required. We discuss the evolution and adaptive radiation of these rare and threatened species with particular reference to the possible role of heterochrony.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 69–83.  相似文献   

2.
3.
During a stay at the Kirstenbosch Research Centre in Cape Town (South Africa), several groups of Asteraceae were studied. One of these was the genus Marasmodes (tribe Anthemideae). After a careful taxonomic study of additional material, including the first species described by A. P. de Candolle, the author has concluded that eight collections should be considered as new species. These new species are described and their relationships with the most similar species of the genus are discussed. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 330–342.  相似文献   

4.
The southern African pholcid spiders previously assigned to Pholcus and Spermophora are revised and their phylogenetic position within Pholcidae is analysed cladistically. Two distinct groups are recognized: the first is restricted to the Cape region and probably correctly placed in Spermophora ; it includes Spermophora peninsulae Lawrence and four new species. The second is more widely distributed in southern and eastern South Africa, and reaches as far north as Cameroon, Congo (Democratic Republic) and Uganda; it is assigned generic status ( Quamtana gen. nov .), and includes two species transferred from Pholcus [ Q. leptopholcica (Strand), Q. ciliata (Lawrence)] as well as 23 new species. A key to the pholcid spiders of South Africa is presented. A close correlation between a male character (distance between cheliceral apophyses) and a female character (distance between pockets on epigynum) is documented in Quamtana .  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society, 2003, 139 , 477−527.  相似文献   

5.
A new species, Bellium artrutxensis (Asteraceae: Astereae), is described from the therophytic pastures of southern Minorca (Balearic Islands). The analysis of nuclear ribosomal internal transcribed spacer (ITS) sequences showed that the new taxon was closely related to Bellium bellidioides , but differed with regard to the annual lifespan, the absence of epigeal stolons, and the presence of a patent eglandular indumentum on the leaves. The new taxon shows morphological features that are well suited for the colonization of dry environments with a marked summer drought, and may be of adaptive significance. The new species is diploid (2 n  = 18) and shows up to two accessory chromosomes in root tissues. B chromosomes have not been reported previously in other species of Bellium .  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 65–77.  相似文献   

6.
7.
Hexabathynella is the only cosmopolitan genus of the order Bathynellacea (Crustacea). The known species number 18, found in Europe (9), Africa (1), South America (2), North America (3) and Australia and New Zealand (3). Phylogenetic analysis suggests that the least derived species are those from South America and the most derived those from the Iberian Peninsula, North America and Australia. The five species with the most plesiomorphic characters occur in salt or brackish water, which supports a marine origin for the genus. Phylogenetic and biogeographical analyses suggest that the distribution of the genus can be explained by dispersion and a double vicariant biogeographical model based on plate tectonics and the evolution of the Tethys during the Mesozoic and Cenozoic.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78 , 457–466.  相似文献   

8.
A new species of Sarcinomyces , a melanized fungus with meristematic development, is described. On the basis of small subunit and internal transcribed sequence regions of ribosomal DNA sequencing, the new species was accommodated in the anamorph genus Sarcinomyces (Herpotrichiellaceae, Chaetothyriales) close to S. petricola .  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 373–380.  相似文献   

9.
Clivia robusta B.G. Murray, Ran, de Lange, Hammett, Truter et Swanevelder sp. nov. (Amaryllidaceae) is a tubular, pendulous-flowered Clivia species, restricted to the Pondoland Centre of Endemism, South Africa. The unique morphology, distribution, karyotype and molecular fingerprint distinguish it from all other pendulous-flowered species in the genus.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 369–374.  相似文献   

10.
Scanning and electron microscopic studies of the pollen grains of several species of the sub-Saharan African and Madagascan genus Aristea of c . 50 species, supplement data from an earlier study and enable us to include these species in a phylogenetic analysis. TEM examination of a range of pollen grains of representative pollen types in Aristea makes it possible to reinterpret past SEM results so that apertures covered with exine masses and previously called sulculate, are now seen to be either zonasulculate or dizonasulculate. Revised and expanded data are combined in a matrix together with new data for seed morphology in the genus, which like the capsules is remarkably diverse, including angular seeds with reticulate sculpturing, lamellate or triangular-columnar seeds with smooth or reticulate surfaces and with smooth or papillate or areolate margins. This new phylogenetic analysis suggests that Aristea should remain treated as comprising three subgenera. In subgenus Eucapsulares we add a new section Latifolieae for A. latifolia , which seems an isolated relic restricted to the mountains of the Cape Region of South Africa, an area of winter rainfall. Species with similar unspecialized capsule and seed morphology occur only in eastern south and tropical Africa and Madagascar, but they have derived pollen morphology whereas the pollen of A. latifolia is plesiomorphic. This species appears to be the closest living ancestor of the genus. In subgenus Aristea we continue to recognize three sections, sect. Racemosae , sect. Singulares and sect. Aristea. Nesting of subgenus Pseudaristea within section Racemosae of subgenus Aristea is probably an artefact of the analysis and does not receive bootstrap support, and hence we continue to recognize this group of species at subgeneric rank.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 41–68.  相似文献   

11.
Arctotis debensis R.J.McKenzie, a new species from the Albany Centre of Floristic Endemism, South Africa, is described and illustrated. It grows almost exclusively in grassland on kommetjies, a distinctive landform of depressions and mounds associated with giant earthworms, in a restricted area west of King William's Town, Eastern Cape Province. It is the first plant taxon reported to be endemic or near-endemic to this unusual habitat. The new species appears to have been collected rarely and previous collections examined have remained undetermined to species level. The new species is distinguished from closely allied species by the combination of its usually larger dimensions in all parts, prostrate habit, coriaceous leaves that are green, scabrous, and eglandular on the adaxial surface and densely lanate on the abaxial surface, and involucral-bract morphology.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 581–588.  相似文献   

12.
This paper presents the karyotype and DNA content of 12 diploid species of Hippeastrum from South America. The variation in genome size is compared with the karyotype and DNA content of Amaryllis belladonna from South Africa. The Hippeastrum species present a uniform and bimodal basic karyotype formula, but significant differences are found in the total chromosome volume (TCV) and nuclear DNA content. A positive correlation between the DNA content and TCV is also observed. The karyotype's constancy is a product of changes in DNA content occurring in the whole chromosome complement. The DNA addition to the long and short sets of chromosomes varies independently. In species with higher DNA contents, the short chromosomes add equal DNA amounts to both arms, maintaining their metacentric morphology, whereas the long chromosomes add DNA only to the short arm, increasing the chromosome symmetry. These data show that the evolutionary changes in DNA amount are proportional to chromosome length, maintaining the karyotypic uniformity. A. belladonna has a larger DNA content and possesses a karyotype different from that of Hippeastrum spp., supporting the distinction between the two genera and upholding the name Amaryllis for the South African entity against Hippeastrum for the South American genus.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 171–178.  相似文献   

13.
The genus Killickia is described to accommodate the South African endemic species formerly placed in Micromeria sect. Hesperothymus . Morphological data, as well as results from unpublished phylogenetic studies support its separation from the genera Micromeria and Clinopodium . A new species Killickia lutea Bräuchler is described and three new combinations are made. Killickia is characterised as comprising solitary- or few-flowered cymes, a campanulate to subcampanulate (obconical) calyx with similar teeth, a corolla tube with two pubescent ridges and nutlets with scattered minute hairs. A thickened marginal vein in the leaves as typical for Micromeria is absent. As currently understood all species are restricted to the Drakensberg mountains and KwaZulu-Natal Midlands in eastern South Africa. A key to the species, brief notes on anatomy and ecology are provided.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 575–586.  相似文献   

14.
The pulmonate snails of the genus Biomphalaria are widely distributed in the tropics, and they are intermediate hosts of the digenean trematode Schistosoma mansoni that causes intestinal schistosomiasis in humans. Recent molecular evidence suggests that Biomphalaria originated in South America, and following a recent transatlantic migration colonized Africa, where it radiated into the currently recognized 12 species. In the present study we further investigate the internal phylogenetic relationships of African Biomphalaria with emphasis on the dispersal and speciation on the continent, especially in the Great Lakes in East Africa. Our results, based on 16S ribosomal DNA, cytochrome oxidase subunit I (COI), and ribosomal internal transcribed spacer I (ITS1), support the monophyly of an African clade with two separate lineages ( Biomphalaria pfeifferi / Biomphalaria camerunensis and the Nilotic species complex/ Biomphalaria angulosa ). Following the initial colonization of Africa, Biomphalaria spread towards the east where a later radiation occurred in the Lake Victoria basin and the Albertine Rift Valley Lakes. With further dispersal along the River Nile, additional speciation took place giving origin to the North-east African species Biomphalaria alexandrina . Our results present almost no support of the species groups of Mandahl-Barth (except for the pfeifferi group), which is in accordance with other molecular appraisals. Our results suggest that Biomphalaria stanleyi , which is endemic to Lake Albert, is not an ecophenotype of the continental B. pfeifferi as previously suggested by other molecular studies. B. angulosa is sequenced for the first time and it is inferred to have an important phylogenetic position as sister group to the Albertine Rift/Lake Victoria basin radiation.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 151 , 337–349.  相似文献   

15.
16.
A previously unknown Annonaceae species from the South Pacific island of New Caledonia is described as Goniothalamus dumontetii . This is the first Goniothalamus species reported from the island, and the easternmost record for the genus. It is easily distinguished from its congeners by the shape of the monocarp (flattened elongate with lateral triangular projections), which reflects the shape of the seeds (flattened rhombohedral). The conservation status of the species is evaluated as endangered (EN) using World Conservation Union (IUCN) red list categories, as it is known from only one relatively small population. The interpretation of geological and molecular data suggests that Goniothalamus dispersed to New Caledonia relatively recently, and does not represent a relict of the break-up of Gondwana.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 497–503.  相似文献   

17.
The genus Labulla Simon is circumscribed in phylogenetic terms to include the species Labulla thoracica (Wider), L. flahaulti Simon and L. machadoi sp. nov. The genital anatomy of the genus is described in detail and the taxonomy of the genus is reviewed. The monophyly of Labulla is supported by numerous morphological apomorphies of the male palp and female epigynum. Based on a cladistic analysis, a new genus, Pecado gen. nov. , is erected to place Labulla impudica Denis, from Northern Africa. Lepthyphantes insularis Saito and ' Labulla ' nepula Tikader, both formerly included in Labulla , are not congeneric with the type species of Labulla .  © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005, 143 , 359–404.  相似文献   

18.
This work comprises 24 reports of chromosome numbers in 24 Artemisia L. species from Asia. Ten are included in the subgenus Dracunculus Besser and the rest belong to other subgenera. Seven counts are new reports, 14 are consistent with scarce previous ones, and three contribute new ploidy levels. That carried out in A. medioxima reports the highest ploidy level ever counted for the genus (16 x ). There is only one species with x  = 8 as the basic chromosome number. In the remaining x  = 9-based species, ploidy levels range from 2 x to 16 x , illustrating the great role played by polyploidy in the evolution of the genus.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 301–310.  相似文献   

19.
Hymenaea mexicana sp. nov. is described in amber originating from mines of Chiapas, Mexico. The species is characterized by clawed showy petals with cordate bases and glabrous, verrucose ovaries with long hirsute hairs at their bases and margins on one side. This species is closely related to the extinct Hymenaea protera from Dominican amber, and together with it, is placed in the primitive section Trachylobium of the genus Hymenaea in the caesalpinoid legumes. The closest extant species to H. mexicana is H. verrucosa , a relict surviving in East Africa. These results challenge previous views that Mexican amber was produced by the South American species H. courbaril – H. intermedia , which belong to the advanced section of the genus.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 125–132.  相似文献   

20.
Fossil remains of Curtisia Aiton (Cornales) are recognized for the first time from the Tertiary of Europe, based on early Eocene anatomically preserved fruits from the London Clay and Poole Formations of southern England. The modern distribution of this monotypic genus is limited to the cape of South Africa. Curtisia quadrilocularis (Reid & Chandler) comb. nov. fruits have globose tetralocular endocarps composed of isodiametric sclereids with a single seed per locule, a prominent axial vascular canal, apical placentation, and four germination valves. All of these characters, as well as size, correspond to extant Curtisia . Although many fossil taxa from the Eocene of Europe have been shown to have their closest extant relatives in Asia, this occurrence of Curtisia highlights Tertiary floristic exchange between Europe and Africa. The newly recognized fossil occurrences suggest a Laurasian origin for Curtisia , in conformity with the fossil record for several other genera of the Cornales. In addition, our rejection of the former assignment of this species to Leucopogon causes us to question whether Epacridaceae were present in the Tertiary of Europe.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 127–134.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号