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 31 毫秒
1.
由于生活史特殊以及分类学历史复杂, 国内外有关梨甲藻科物种的分类学研究比较少。本研究通过形态分类学方法, 详细阐述了梨甲藻物种的分类学历史沿革, 对我国海域的11种梨甲藻科物种的孢囊进行了分类学研究。我们认为其中的1种应隶属于球甲藻属(Dissodinium), 其余10种可归为梨甲藻属(Pyrocystis)(包括2个变种, 2个变型), 对每个物种都进行了详细的形态学描述, 认为拟新月球甲藻(Dissodinium pseudolunula)与新月梨甲藻(Pyrocystis lunula)、优美梨甲藻(Pyrocystis elegans)与粗梨甲藻(Pyrocystis robusta)的分类学关系还需要进一步研究。  相似文献   

2.
The genus Cayratia Juss. in the traditional sense (i.e., Cayratia s.l.) of the grape family has been shown to be non‐monophyletic. Previous studies supported the splitting of Cayratia s.l. into three genera, that is, Cayratia s.s., Causonis Raf., and a new genus representing the African Cayratia clade. However, the morphology of the African Cayratia clade has not been studied carefully and its phylogenetic position within Vitaceae remains unclear. Our study integrates molecular, distributional, and morphological data and supports the recognition of the new genus Afrocayratia from continental Africa and Madagascar. Phylogenetic analyses strongly support the monophyly of Afrocayratia and resolve it as a sister of Cayratia s.s. based on the chloroplast data, but it is placed sister to Cyphostemma based on the internal transcribed spacer dataset. Molecular dating suggests that Afrocayratia split with Cayratia s.s. during the Paleocene, but that the extant species of Afrocayratia did not diversify until the early Miocene. Afrocayratia differs from its allied genera in having short stigmas and seeds with subcircular ventral infold cavities in cross‐section. Three clades are detected within Afrocayratia, with A. debilis (Baker) J.Wen & L.M.Lu as the first diverged lineage. The second diverged lineage includes A. delicatula (Willems) J.Wen & Z.D.Chen and A. gracilis (Guill. & Perr.) J.Wen & Z.D.Chen. The third diverged lineage includes A. imerinensis (Baker) J.Wen & L.M.Lu, A. longiflora (Desc.) J.Wen & Rabarijaona, and A. triternata (Baker) J.Wen & Rabarijaona from Madagascar, which form a monophyletic group that diverged from the second lineage in the middle Miocene. Combining the morphological and molecular evidence, we formally describe the new genus Afrocayratia, make seven new combinations, and provide a key to species of the genus.  相似文献   

3.
4.
Saxifraga L. is the largest genus in Saxifragaceae and a characteristic component of the herbaceous flora of the temperate and alpine mountains in the Northern Hemisphere. Section Irregulares is a small group of 15–20 species, representing one of the early‐diverged lineages in the genus characterized with unique zygomorphic flowers. We used both nuclear internal transcribed spacer and chloroplast DNA regions (psbA‐trnH, trnL‐F, and matK) to reconstruct its species relationships, estimate divergence times, and infer its historical biogeography. Our phylogenetic results corroborate the monophyly of sect. Irregulares and its sister relationship to sect. Heterisia from North America. The section was well resolved into two lineages corresponding to their morphological features and biogeographic distributions. One represents ser. Stoloniferae including S. stolonifera Curtis and S. nipponica Makino with long‐creeping stolons/rhizomes and small petals with spots and the other comprises the remaining taxa (ser. Rufescentes) which lack long‐creeping rhizomes. Spots on leaves (abaxially spotted vs. abaxially without spots) and spots on petals (without spots vs. with spots) are inferred to be phylogenetically informative within ser. Rufescentes. Divergence time estimates and ancestral area analysis suggested a western North American origin of sect. Irregulares with migration into East Asia by way of the Bering land bridge in the Middle Oligocene. The development of drying and desertification belt in the late Miocene could have played an important role in the subsequent restriction and separation of the north and south lineages within eastern Asia.  相似文献   

5.
6.
Most of the mitochondrial NADH dehydrogenase subunit 5 (ND5) gene and a part of nuclear 28S ribosomal RNA gene were sequenced for 14 species of ground beetles belonging to the genus Leptocarabus. In both the ND5 and the 28S rDNA phylogenetic trees of Leptocarabus, three major lineages were recognized: (1) L. marcilhaci/L. yokoael/Leptocarabus sp. from China, (2) L. koreanus/L. truncaticollis/L. seishinensis/L. semiopacus/L. canaliculatus/L. kurilensis from the northern Eurasian continent including Korea and Hokkaido, Japan, and (3) all of the Japanese species except L. kurilensis. Clustering of the species in the trees is largely linked to their geographic distribution and does not correlate with morphological characters. The species belonging to different species groups are clustered in the same lineages, and those in the same species group are scattered among the different lineages. One of the possible interpretations of the present results would be that morphological transformations independently took place in the different lineages, sometimes with accompanying parallel morphological evolution, resulting in the occurrence of the morphological species belonging to the same species group (= type) in the different lineages.  相似文献   

7.
陆玲娣 《植物研究》1984,4(4):37-59
桂樱属(Laurocerasus Tourn.ex Duh.)是蔷薇科李亚科的一个属。它是De Tournefort(Institutiones rei Herbariae 627.t.403.1700)以Prunus laurocerasus L.和P.lusitanica L.两种奠定基础,而至1755年由Duhmal代为正式发表而建立。自该属建立以后的二百多年来,各国植物学家对其分类位置各持不同观点。  相似文献   

8.
Ancient lakes have long been recognized as evolutionary theatres and hot spots of endemism; the evolution of their morphologically often highly diverse species flocks has received much attention. However, as each ancient lake has its own geological and evolutionary history, modes of speciation may differ from system to system. Ancient lakes can act as evolutionary reservoirs that assure the survival of relict species, but at the same time extant species may evolve through intralacustrine speciation. Other aspects of interest are the actual rates of immigration, diversification or extinction as well as the temporal framework of morphological change. Many of these questions have been addressed in the African (e.g. Lake Tanganyika) and Asian (e.g. Lake Baikal) ancient lakes. For an European ancient lakes (e.g. Lakes Ohrid and Prespa), such studies are largely missing. In the present paper, extraordinarily shaped endemic freshwater limpets of the genus Ancylus from the Balkan Lake Ohrid are used in a phylogeographic and phylogenetic context to test whether they represent an ancient lake species flock, to study the mode of speciation, and to assess the timing of morphological change. Based on DNA data from two mitochondrial genes (COI, LSU rDNA), it has been found that the Lake Ohrid Ancylus species form an endemic monophyletic group. In addition, the lake's feeder springs are inhabited by another, undescribed Ancylus species. All other studied waterbodies within the watershed do not support their own Ancylus lineages but are inhabited by a widespread Mediterranean taxon. The split between the species endemic to the lake and its sister taxon is dated to 1.4±0.6 million years ago. The study presents the first genetic confirmation for the existence of a species flock in a European ancient lake. Contrary to the prevailing opinion it shows that, concerning Ancylus, Lake Ohrid represents a site of intralacustrine speciation rather than an evolutionary reservoir. Moreover, it provides the first evidence for rapid morphological change in an European ancient lake species flock. See also Electronic Supplement at: http://www.senckenberg.de/odes/06-12.htm.  相似文献   

9.
刘艳艳  刘畅  魏晓新 《生物多样性》2022,30(2):21344-Boston
合理的物种划分和深入的系统学研究对理解物种的进化历史、物种编目以及生物多样性保护具有重要意义。松属(Pinus)是裸子植物中最大的一个属, 也是北半球针叶林的重要组成成分。白松亚组(Subsect. Strobus)隶属于松属白松亚属(Subg. Strobus)五针松组(Sect. Quinquefoliae), 是松属物种数目最多的亚组之一, 其中半数以上物种分布在我国及周边地区。白松亚组(又称五针松亚组)所有物种针叶均为五针一束, 由于形态相近、种间遗传分化小和野外调查不充分, 这些五针松的物种界定和种间关系一直存在很多争议。此外, 亚热带地区大多数五针松物种的地理分布非常狭窄或群体片断化严重, 已有多个物种被IUCN评估为受威胁物种。在2021年9月我国新发布的《国家重点保护野生植物名录》中, 大别山五针松(Pinus dabeshanensis)和毛枝五针松(P. wangii)也由原国家二级保护野生植物调升为国家一级保护野生植物。近年来, 得益于系统发育基因组学在裸子植物等大基因组的木本植物类群中的成功应用, 我国及周边地区五针松的种间关系和群体历史得到初步解析。本文主要回顾和总结了我国及周边地区的五针松在系统分类、群体遗传及物种保护等方面取得的进展和存在的不足, 提出未来应当充分重视基础研究和野外调查, 并加强学科交叉以及新技术和新方法在相关研究中的应用以实现濒危物种的精准保护。  相似文献   

10.
Halimeda (Bryopsidales), a genus of calcified, segmented green seaweeds, abounds in reefs and lagoons throughout the tropics. To investigate phylogenetic, phylogeographic, and historic ecological relationships of the genus, the nuclear rDNA including the SSU and both ITS regions were sequenced. A maximum likelihood tree revealed the following: (1) there were anatomical and morphological synapomorphies for five well-supported lineages; (2) the last common ancestor of one lineage invaded sandy substrata; those of two other lineages established in wave-affected habitats, whereas the cenancestor of the remaining two lineages occupied sheltered rocky slopes. Yet, several species adapted to new habitats subsequently, resulting in several cases of convergence; (3) all lineages separated into Atlantic and Indo-Pacific daughters, likely resulting from the rise of the Panamanian Isthmus. Each daughter pair gave rise to additional convergent species in similar habitats in different oceans; (4) Halimeda opuntia, the only monophyletic pantropical species detected so far, dispersed from the Indo-Pacific into the Atlantic well after the closure event; (5) minor SSU-sequence differences across species and phylogeographic patterns of vicariance indicated a relatively recent diversification of the extant diversity. Cretaceous and Early Tertiary fossil look-alikes of modern species must then have resulted from iterative convergence.  相似文献   

11.
The family Tetrablemmidae is reported for the first time from China, with five new species and one new genus. Lehtinenia gen. n., which is erected to accommodate Lehtinenia bicornis sp. n., is characterized by the modified embolus, special modifications on chelicerae, and a Tetrablemma-type vulva. The other four new species are: Ablemma prominens sp. n., Brignoliella caligiformis sp. n., Brignoliella maoganensis sp. n., and Tetrablemma brevidens sp. n., all collected from caves. A phylogenetic analysis of the subfamily Tetrablemminae based on 41 morphological characters shows that the tribe Brignoliellini is the most basal group in the subfamily, rather than the sister group to the tribe Fallablemmini. Lehtinenia gen. n. and the genera Ablemma, Sulaimania, and Maijana together form a monophyletic group.  相似文献   

12.
Cryptic species of passerine birds lack notable morphological differentiation and can best be identified by molecular and bioacoustic markers. Here we investigate seven cryptic species of the golden-spectacled warbler (Seicercus burkii complex) with respect to territorial song and cytochrome-b (cyt-b) sequences. Their phylogenetic relations to other Seicercus species and to members of the genus Phylloscopus are inferred by the same methods. Three separate lineages of Seicercus are nested within different branches of the molecular Phylloscopus tree. The S. burkii complex is a monophyletic unit comprising seven species (S. burkii s. str., S. whistleri, S. valentini, S. soror, S. omeiensis, S. tephrocephalus and S. affinis). S. xanthoschistos turned out to be a close relative of Phylloscopus davisoni within the P. reguloides group. Two isolated sister taxa, S. grammiceps and S. castaniceps, also branch together with the P. reguloides group. Within the S. burkii complex the overall haplotype and nucleotide diversity is highest in taxa from the Chinese middle and upper mountain belt (S. valentini, S. omeiensis and S. soror), indicating at least partially restricted gene flow in these species. This is explained by the fragmentation of high-altitude habitats in China while in the Himalayas the vicariant species S. whistleri inhabits a more continuous mountain belt at the same altitude. For the Chinese species from medium and high altitudes, past range expansion is indicated by significantly negative Tajima Ds. According to pairwise genetic distances, most species of the S. burkii complex have diverged 5 myr ago, the most recent split between S. burkii and S. tephrocephalus is dated 2 myr ago. Coalescence times for haplotype lineages of the different species range from 9 up to 12 myr, and between 5 and 6 myr for S. burkii and S. tephrocephalus.

Within Seicercus divergence of song features such as frequency parameters and syntax structures correlate with genetic distances between taxa. The three cyt-b lineages of Seicercus correspond to different clusters in a discriminant analysis by acoustic parameters. Common syntax structures of territorial song in the Phylloscopus/Seicercus assemblage are: (1) an introductory element derived from specific calls and (2) a syntax of trills and repeated element groups or a combination of both. There are clear indications that these song structures have repeatedly emerged, were lost or were altered in different branches of the phylogenetic tree at different times. Absolute differences between taxa in frequency parameters or in an acoustic divergence index increase significantly with growing genetic distances. However, due to multiple parallel evolution phylogenetic information provided by single acoustic traits decreases with increasing numbers of taxa involved in the investigation.  相似文献   


13.
On the basis of new material from various Pacific regions we critically evaluate the characters for the taxonomy of the genus Questa and the former Questidae, a taxon now concluded to be a lineage within the family Orbiniidae. Two new species, Questa retrospermatica sp. n. from Hawaii (with similar forms also from New Caledonia and China), and Questa fijiensis sp. n. from Fiji, are described, and the morphological character patterns and phylogeny of the genus are revisited on the basis of a cladistic analysis. The finding of Hawaiian material of a new species, Levinsenia hawaiiensis sp. n., similar to Periquesta canariensis Brito & Nunez, 2002 (=Levinsenia canariensis comb. n.), challenges the view that Periquesta Brito & Nunez, 2002 is closely related to Questa; rather, it belongs to Paraonidae as a junior synonym of Levinsenia Mesnil, 1897.  相似文献   

14.
陈艺林 《植物研究》1986,6(2):37-46
裸菀属Miyamayomena Kitam.是北村四郎1)(1937)从马兰属Kali-meris Cass.(Asteromaea B1.)分出的一个小属,隶属于菊科紫菀族Trib.Astereae Cass.紫菀亚族Asterinae O.Hoffm,本属发表时,曾取名为Gymnatser Kitam。主要以瘦果顶端具狭环状边缘而无冠毛,与具糙毛状或膜片状短冠毛的马兰属相区别。  相似文献   

15.
16.
Molecular phylogenetic studies based on Sanger sequences have shown that Cyperaceae tribe Fuireneae s.l. is paraphyletic. However, taxonomic sampling in these studies has been poor, topologies have been inconsistent, and support for the backbone of trees has been weak. Moreover, uncertainty still surrounds the morphological limits of Schoenoplectiella, a genus of mainly small, amphicarpic annuals that was recently segregated from Schoenoplectus. Consequently, despite ample evidence from molecular analyses that Fuireneae s.l. might consist of two to four tribal lineages, no taxonomic changes have yet been made. Here, we use the Angiosperms353 enrichment panel for targeted sequencing to (i) clarify the relationships of Fuireneae s.l. with the related tribes Abildgaardieae, Eleocharideae, and Cypereae; (ii) define the limits of Fuireneae s.s., and (iii) test the monophyly of Fuireneae s.l. genera with emphasis on Schoenoplectus and Schoenoplectiella. Using more than a third of Fuireneae s.l. diversity, our phylogenomic analyses strongly support six genera and four major Fuireneae s.l. clades that we recognize as tribes: Bolboschoeneae stat.nov., Fuireneae s.s., Schoenoplecteae, and Pseudoschoeneae tr. nov. These results are consistent with morphological, micromorphological (nutlet epidermal cell shape), and embryo differences detected for each tribe. At the generic level, most sub-Saharan African perennials currently treated in Schoenoplectus are transferred to Schoenoplectiella. Our targeted sequencing results show that these species are nested in Schoenoplectiella, and their treatment here is consistent with micromorphological and embryo characters shared by all Schoenoplectiella species. Keys to recognized tribes and genera are provided.  相似文献   

17.
杜鹃花属植物花粉形态及其分类学意义   总被引:19,自引:0,他引:19  
王玉国  李光照  漆小雪  欧祖兰   《广西植物》2006,26(2):113-119
利用扫描电子显微镜对5个亚属20种杜鹃花属植物的花粉形态进行了观察和比较研究,其中大部分(16种)为首次报道。杜鹃花属花粉均为四合花粉,呈正四面体排列。四合体为圆角三角形,连接紧密。单粒花粉为球形或近球形,具三沟孔。在扫描电镜下,除了杜鹃亚属的百合杜鹃、羊踯躅亚属的羊踯躅以及马银花亚属的马银花组具有明显的纹饰特征之外,其它类群的形态特征相互重叠,不足以作为现有亚属的分类依据。花粉粒具不同的外壁纹饰,可为分类研究提供孢粉学方面的证据,但应慎重应用花粉形态对杜鹃花属植物特定种进行分类鉴定。  相似文献   

18.
Scapania is a northern temperate genus with a few disjunctions in the south. Despite receiving considerable attention, the supraspecific classification of this genus remains unsatisfactorily solved. We use three molecular markers (nrITS, cpDNA trnL-F region, atpB-rbcL spacer) and 175 accessions belonging to 50 species (plus eight outgroup taxa) to estimate the phylogeny and to test current classification systems. Our data support the classification of Scapania into six rather than three subgenera, rearrangements within numerous sections, and inclusion of Macrodiplophyllum microdontum. Scapania species with a plicate perianth form three early diverging lineages; the most speciose subgenus, Scapania s.str., represents a derived clade. Most morphological species concepts are supported by the molecular topologies but classification of sect. Curtae requires further study. Southern lineages are nested in northern hemispheric clades. Palearctic-Nearctic distribution ranges are supported for several species.  相似文献   

19.
Gunnar Gad   《Zoologischer Anzeiger》2005,243(4):239-271
Two new species of the genus Pliciloricus Higgins & Kristensen, 1986, are described from coarse sand at the plateau of the Great Meteor Seamount. Together with other species of the genus, Pliciloricus corvus sp. n. and Pliciloricus senicirrus sp. n., demonstrate that the last or seventh instar Higgins-larva can be more and more reduced.

Additionally, in the life cycle of P. corvus sp. n. a simplified adult is discovered which has a simplified body with persisting neck region and a sack-like trunk. The adult of P. corvus sp. n. is characterized, e.g., by 15 broad cross-walls in the clavoscalids, midventral spinoscalids of the second row transformed into a new type of double-organ, a secondary double-organ in the third row of scalids, type B spinoscalids of the fourth row ending in a grappling hook, a crescent-shaped ornamentation of the lorica margin with rounded gaps and protrusions, and a pair of longitudinal cuticular protrusions on the end cone. Distinguishing features of the first to sixth instar Higgins-larvae of P. corvus sp. n. are, e.g., setae of moderate length and long end spines of toes with double bulges. The seventh instar Higgins-larva of P. corvus sp. n. is not fully developed, e.g., the abdominal region is indistinct; the scalids, toes, and all five pairs of setae are clearly shorter than in the preceding instars of Higgins-larvae.

The adult of P. senicirrus sp. n. is characterized, e.g., by clavoscalids with many fine transversal striae, claw-like type B spinoscalids of the fourth row ventrally winged and with seven embedded needle-like teeth, edge of the lorica with 24 small protrusions, and 20 papillate flosculi at caudal end. The Higgins-larva of P. senicirrus sp. n. is characterized, e.g., by the wide and frill-like first section of the mouth cone, the second segment of spinoscalids with ventral serration and double tip, long anterosetae with strong spinules, and by the toes being nearly as long as the short lorica, to name a few. The most obvious feature is the extreme length of the three pairs of posterosetae. The posteroterminal setae are nearly as long as the whole body. The seventh instar Higgins-larva of P. senicirrus sp. n. is not reduced as in the case of P. corvus sp. n.  相似文献   


20.
A new retiolitid genus Cometograptus, restricted to the lundgreni Biozone (Late Wenlock), is characterized by a combination of primitive features such as strong transverse rods and ancora sleeve lists with seams facing out, with advanced features such as a long sicula, central, free nema and pustulose bandages. Cometograptus links two Subfamilies of the Family Retiolitidae. The Subfamily Retiolitinae is divided into redefined lineages: Pseudoretiolites, Retiolites, Paraplectograptus, whereas the Subfamily Plectograptinae is divisible into the Sokolovograptus (questionable), Gothograptus, Spinograptus, Plectograptus lineages, and Cometograptus. The Sokolovograptus group, the first retiolitids bearing ancora sleeve lists with seams facing out, did not survive the lundgreni crisis. The only survivors were Upper Wenlock retiolitids of the Gothograptus lineage. The new genus Cometograptus includes Cometograptus koreni n.gen. and n.sp., Cometograptus tomczyki n.gen. and n.sp., as well as the previously described Cometograptus nevadensis, Cometograptus marsupium and Cometograptus apoxys.  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