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 15 毫秒
1.
2.
The species recently described as Acanthostomum macroclemidis possesses the gonotyl in the form of a solid muscular pad uniquely diagnostic for species of Proctocaecum and is accordingly transferred to that genus. An artificial key to the 5 acanthostomine genera, as well as an updated phylogenetic hypothesis for the 10 known species of Proctocaecum, based on 11 characters and including 2 species described since the last phylogenetic analysis, are presented. The single most parsimonious phylogenetic tree with a consistency index of 87.5% suggests that Proctocaecum originated in Africa and spread to North America and South America before the breakup of Pangaea. As a result, the 2 North American and 1 South American species are most closely related to different African members of the genus. African and Indo-Pacific species inhabit crocodylids; hence, the occurrence of North American species in alligatorids and chelonians and a South American species in alligatorids are the result of host switches.  相似文献   

3.
Three species of Trivia were collected from subtidal habitats in the Cape of Good Hope Peninsula, South Africa. The morphology of T. ovulata (Lamarck, 1811), T. millardi (Cate, 1979) and T. verhoefi sp. nov. is described. Each species can be distinguished by a unique pattern of mande coloration, conchological characters of the fossula and shape of the radular teeth. The central nervous system was examined and found to be of the same configuration in die diree South African spe Trivia ovulata and T. verhoefi appear to be gonochoric while T. millardi is a protandric hermaphrodite. Trivia ovulata and T. millardi also differ in the position of the receptaculum seminis. Differences in internal morphology reported in previous work and the present study are discussed. The fact that the central nervous system of Trivia is euthyneurous is reconfirmed. Trivia ovulata and T. millardi were associated with colonial tunicates as previously recorded for other members of the genus.  相似文献   

4.
It is generally accepted that accentuated global climatic cycles since the Plio-Pleistocene (2.8 Ma ago) have caused the intermittent fragmentation of forest regions into isolated refugia thereby providing a mechanism for speciation of tropical forest biota contained within them. However, it has been assumed that this mechanism had its greatest effect in the species rich lowland regions. Contrary evidence from molecular studies of African and South American forest birds suggests that areas of recent intensive speciation, where mostly new lineages are clustered, occur in discrete tropical montane regions, while lowland regions contain mostly old species. Two predictions arise from this finding. First, a species phylogeny of an avian group, represented in both lowland and montane habitats, should be ordered such that montane forms are represented by the most derived characters. Second, montane speciation events should predominate within the past 2.8 Ma. In order to test this model I have investigated the evolutionary history of the recently radiated African greenbuls (genus Andropadus), using a molecular approach. This analysis finds that montane species are a derived monophyletic group when compared to lowland species of the same genus and recent speciation events (within the Plio-Pleistocene) have exclusively occurred in montane regions. These data support the view that montane regions have acted as centres of speciation during recent climatic instability.  相似文献   

5.
The endemic diversification of the Cape zone fauna and the phylogenetic relationships among the 30 species of the blister beetle genus Iselma are investigated. We analysed morphological, molecular (mtDNA 16S) and combined datasets of characters using a number of approaches (maximum parsimony, maximum likelihood, Bayesian inference analyses). We propose hypotheses of diversification times among taxa from molecular clock analyses. Morphological and molecular analyses produced similar results. According to maximum likelihood molecular studies, radiation within the genus Iselma occurred during the Pliocene and Pleistocene, roughly contemporaneously with the shift in African climate, vegetation and faunal assemblages. Two main lineages, one Namibian and one South African, separated c. 4.9 Ma. Within the South African lineage we identify two groups of endemic species, one in Little Karoo and one that extend towards southern Namaqualand. The remaining South African groups of species are spread through Namaqualand and the southwestern Cape area. These include several endemisms, with different times of diversification during the Pleistocene, probably related in part to glacial cycles. These endemisms are distributed in small areas of the following ecosystems: coastal Strandveld, Succulent Karoo and particularly Fynbos.  相似文献   

6.
BW Price  X Liu  FC de Moor  MH Villet 《ZooKeys》2012,(201):27-41
The monotypic South African alderfly genus Leptosialis Esben-Petersen, 1920 is reviewed and Leptosialis africana Esben-Petersen, 1920 is redescribed. In the process a new species of alderfly Leptosialis necopinatasp. n. from the Eastern Cape and KwaZulu-Natal provinces of South Africa is recognised and described. Within Sialidae the new species most closely resembles Leptosialis africana. A key to the two species of Leptosialis using both adult and larval characters is provided.  相似文献   

7.
8.
A new species, Microcavia criolloensis (Rodentia, Caviidae), from the Upper Pleistocene (Sopas Formation) of the northern basin of Uruguay (South America) is described. This species is characterised by an exclusive association of skull and dental state characters. An analysis of similarity including other species of the genus and the related genera of Caviidae was performed. The new species of Microcavia behaved in the phenogram obtained as a discrete unit closely associated to Microcavia chapalmalensis and Microcavia niata. A mosaic of habitats, ranging from open and arid or semiarid microhabitats to fluvial and riparian forests, is suggested here, mainly based on the current adaptations of the genus Microcavia and the records of several taxa of mammals in the Sopas Formation. The geographic area occupied by Microcavia in the Pleistocene was different, with fossil records located more than 500 km eastward with respect to its present distribution. This variation could have occurred as a response to environmental changes in the last interglacial and glacial cycles.  相似文献   

9.
The genus Ptychopetulum (Olacaceae), disjunct between South America (2 spp.) and Africa (2 spp. West Africa; I sp. Rhodesia), exhibits predominantly diploporate pollen among the West African species and predominantly triporate pollen among the South American taxa. An analysis of aperture evolution suggests two possible schemes of aperture evolution for the genus. Scheme I avers the independent origin of both triporate and diploporate apertures from a basic brevicolpate condition while scheme II proposes a basic diploporate condition in which the diploporate apertures have migrated to the equator, fused to form brevicolpi and have ultimately become reduced to pores. Pollen evidence in support of both schemes is discussed. The distribution of aperture types within the genus also suggests West Africa as the original site of aperture evolution and South America as the second area of aperture development with types traceable to West African stock.  相似文献   

10.
Six new species of the Australian myrmecophilous ptinid genus Polyplocotes are described from South Australia. Three are from the deserts of central Australia, one from the Franklin Islands in the Great Australian Bight, one from Eyre Peninsula and one from the Riverland region. Morphologically, the majority of these new species are conventional Polyplocotes , but two are less typical. The characters uniting the genus are explored in the discussion, and comparisons are made to related genera. Although the six new species described here have not been observed in the field, the species of this genus are known to be myrmecophilous, and ant – beetle interactions similar to those seen in other spider beetles might occur between these new species and their host ants.  相似文献   

11.
中国南海蛇鳗科一新纪录属及一新纪录种(鱼纲,鳗鲡目)   总被引:1,自引:0,他引:1  
报道了中国南海蛇鳗科1新纪录属Echelus Rafinesque,1810和1新纪录种Echelus uropterus(Temminck et Schlegel,1846).该属的特征为:尾鳍、胸鳍存在;背鳍起点在胸鳍后端之前;头部无额骨孔、眶后孔和上颞骨孔;鳃孔中等大;鳃膜骨条连于舌骨或上舌骨尖前.该种的特征:尾尖柔软;颌齿和犁骨齿颗粒状,带形;后鼻孔在上唇边缘外侧.  相似文献   

12.
A new genus and species Zagadkogobius ourlazon gen. et sp. nov. characterized by an unusual (for the subfamily Ptereleotrinae) combination of characters is described. A single specimen was collected at a depth of 73 m in the southwestern South China Sea to the south of the Anambas Islands. Based on the combination of characters, the new genus is most similar to the genus Nemateleotris. However, the species of the latter genus are associated exclusively with coral reefs. A key to the genera of the subfamily Ptereleotrinae is presented.  相似文献   

13.
The tribe Psoraleeae (Leguminosae subfamily Papilionoideae) comprises 185 species in nine genera that have a nearly worldwide distribution, occurring predominantly in Mediterranean regions. About 60% of the species belong to the genera, Otholobium C.H.Stirt. and Psoralea L., which have a centre of diversity in the Cape Floristic Region of South Africa. Since previous molecular studies have sampled only a few species of the tribe from this region, this study sought to determine the phylogenetic position of the southern African genera and to test whether they are monophyletic. Phylogenetic relationships were reconstructed using DNA sequence data (trnL-F, rpoB-trnC and ITS) and seven morphological characters, which diagnose the two southern African genera. The data were analysed using the parsimony method. There was strong support for the Psoraleeae as a clade, but most of the nodes within the large genera were poorly supported. The southern African species of Psoralea and Otholobium together formed a strongly supported clade. This clade was sister to the genus Hoita Rydb., but without support. However, the Psoralea species were nested within the southern African Otholobium. Additionally, some South American species that are currently recognised as Otholobium were resolved in a clade distinct from the southern African species, making Otholobium polyphyletic. Morphological characters that separate Otholobium and Psoralea are discussed. Finally, the southern African genera as currently circumscribed are not monophyletic. However, further investigations using more informative DNA loci are required to validate this observation. Furthermore, the taxonomic placement of the South American species needs to be reviewed.  相似文献   

14.
Pollen morphology of 43 African species of the genus Spermacoce has been investigated by scanning electron and light microscopy. The genus is eurypalynous, which is reflected in the remarkable variation of almost all pollen characters. The average equatorial diameter (E) ranges from 15.8 w m to 115.5 w m. Grains are colporate or pororate. The number of apertures varies from 3 up to more than 25. The majority of species has apertures situated only at the equator (being zonoaperturate), but a few species have pantoaperturate grains. The endoaperture is generally an endocingulum, often with a secondary lolongate or lalongate thinning at the ectocolpus; endocolpi and endopores are also observed. The sexine is usually perforate, but eutectate, foveolate, and (micro)reticulate tecta were also found. Supratectal elements are present as granules, microspines or spines. The inner nexine surface is granular, often with irregular grooves (endocracks). Among native African species, nine pollen types are recognized mainly on the basis of pollen size, aperture morphology and tectum peculiarities. In two of the pantoaperturate types, apertures are in a configuration not yet recorded for the angiosperms in general. Some evolutionary trends are proposed that await verification by further systematic study. Pollen morphological characters have a high taxonomic value in the genus Spermacoce . They provide almost unique identification marks for the species, which enables sharpening of species boundaries. Small groups of related species often share the same pollen type. The genus Borreria , previously separated from Spermacoce on the basis of its fruit morphology only, is not supported by pollen data.  相似文献   

15.
The South American grasshopper genus Chlorus (Melanoplinae, Dichroplini) from Bolivia, southern Brazil and Paraguay is revised. Cladistic analysis of morphological characters indicates that Chlorus constitutes a monophyletic group whose generic relationships remain unsolved. If the external morphology is considered, Chlorus showed to be related to Dichromatos , while characters from the male genitalia support the relationship between Chlorus and Eurotettix. Seven species are recognised for Chlorus with three of them described as new: Chlorus spatulus, Ch. chiquitensis and Ch. attenuatus . Keys to the species of the genus and a review of the morphological characters defining the taxa are provided.  相似文献   

16.
Phylogenetic relationships in the largely South African genus Muraltia (Polygalaceae) are assessed based on DNA sequence data (nuclear ribosomal ITS, plastid atpB-rbcL spacer, trnL intron, and trnL-F spacer) for 73 of the 117 currently recognized species in the genus. The previously recognised subgenus Muraltia is monophyletic, but the South African endemic genus Nylandtia is embedded in Muraltia subgenus Psiloclada. Subgenus Muraltia is found to be sister to subgenus Psiloclada. Estimates show the beginning of diversification of the two subgenera in the early Miocene (Psiloclada, 19.3+/-3.4 Ma; Muraltia, 21.0+/-3.5 Ma) pre-dating the establishment of the Benguela current (intermittent in the middle to late Oligocene and markedly intensifying in the late Miocene), and summer-dry climate in the Cape region. However, the later increase in species numbers is contemporaneous with these climatic phenomena. Results of dispersal-vicariance analyses indicate that major clades in Muraltia diversified from the southwestern and northwestern Cape, where most of the species are found today.  相似文献   

17.
18.
This paper consists of a taxonomic and systematic revision of the extinct felid genus Dinofelis (Felidae, Ma-chairodontinae) and an analysis of its ecomorphology and evolution. Dinofelis has a broad distribution, with material from all northern continents and Africa, the latter of which was the apparent centre of evolution of the genus. We describe new material of Dinofelis from a number of sites in eastern Africa and reconsider all previously described material. We name two new species and identify several other distinct species-level taxa but refrain from naming these due to a paucity of well-preserved material. At the same time, we synonymize the two named Asian species, D. cristata and D. abeli , of which the former has priority. There are few characters useful in systematic analysis, but we can suggest at least one migration from eastern to southern Africa. Ecomorphological analysis of both craniodental and postcranial characters suggests that Dinofelis in many respects converged on modern pantherine cats in morphology and behaviour, a trend culminating in the South African D. barlowi and the Asian D. cristata , which are the most pantherine-like of all machairodont felids. This trend is reversed in the evolution of the youngest species, D. piveteaui , which is also the most machairodont in its ecomorphology. The timing of the extinction of Dinofelis is difficult to determine. Outside Africa material is scarce at all times, while in Africa the apparent extinction of Dinofelis at about 1.4 Mya coincides with the end of the good, semi-continuous fossil record present in eastern Africa from about 4 Mya onwards. Dating of Kanam East (with D. piveteaui) to the Jaramillo Subchron (1.070-0.990 Mya) suggests possible survival considerably later. Thus, the extinction datum for Dinofelis cannot at present be firmly established.  相似文献   

19.
Results of phylogenetic analysis based on 34 morphological characters of 24 species of 11 genera of Hopliinae from Europe, Japan, South Africa, Madagascar, North and Central America, indicates that the genus Hoplia is a monophyletic group with species distributed in Europe, Japan and America. Based in this analysis the Asiatic genus Ectinohoplia is the closest relative of the genus Hoplia, and the South American genus Barybas (Melolonthinae: Macrodactylini) is the sister group of Hopliinae.  相似文献   

20.
A New Basal Lystrosaurid Dicynodont from the Upper Permian of South Africa   总被引:1,自引:0,他引:1  
A new genus and species of late Permian dicynodont, Kwazulusaurus shakai , is described on the basis of a complete skull from the late Permian Dicynodon Assemblage Zone of the South African Beaufort Group. It is an advanced form which shows characters, such as the shape of the snout and the loss of the ectopterygoid, that link it to the early Triassic genus Lystrosaurus. Kwazulusaurus represents the most basal member of the lystrosaurian lineage. The phylogeny of progressive pristerodontian dicynodonts is discussed. It appears possible that the Kannemeyeriiformes and Lystrosauridae do not form a monophylum, as previously assumed. Instead a sister-group relationship between lystrosaurids and dicynodontids plus kannemeyeriiforms is suggested.  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