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1.
为探讨瑞香科沉香亚科的分类学地位,结合其他亚科植物的化学成分类型,对从沉香属植物分离到的各类化学成分进行了综述。从二萜和黄酮(烷)的成分类型判断,沉香亚科的进化地位低于瑞香亚科;从三萜成分类型来看,其地位又比Gonystyloideae亚科稍高;同时2-(2-苯乙基)色酮类和二苯基甲酮类成分为沉香属甚至沉香亚科的特征性成分。因此,沉香亚科是瑞香科中进化程度相对较低的类群,处于瑞香亚科和Gonystyloideae亚科之间。  相似文献   

2.
The pollen morphology of 120 samples of the tribe Orobancheae, representing four genera and 40 species of Cistanche, Diphelypaea, Orobanche and Phelipanche native to Turkey, has been studied by light and scanning electron microscopy. Pollen of the tribe Orobancheae is typically isopolar, radially asymmetrical, oblate spheroidal or prolate and belongs to one of the following basic pollen types: inaperturate, tricolpate and syncolpate. Also, pollen heteromorphism is widespread among pest species of Orobanche and Phelipanche. Pollen characters display considerable variation among genera and species, but some characters are significant at the levels of genera and sections. The results of the SEM study show that there are various exine ornamentation types in these genera. The obtained results support the division of the traditionally circumscribed genus Orobanche sensu lato into two genera, Phelipanche and Orobanche. The pollen morphological features are discussed on the basis of molecular phylogeny of the taxa.  相似文献   

3.
The Menispermaceae family contains ca. 72 genera with 450 species that are almost entirely tropical. Its phylogeny at the tribal level has never been examined using molecular data. Here we used DNA sequences of the chloroplast matK gene and trnL-F regions, and the nuclear ITS region to study the delimitation and position of the tribe Menispermeae within the family and its subtribal monophyletic groups. Family-wide phylogenetic analyses of the chloroplast data produced two strongly supported clades. The first clade contains two subclades: Coscinieae including Arcangelisia and Anamirta, and Tinosporeae sensu lato including Fibraureae, supported by morphological characters, such as traits of the cotyledon, stylar scar and embryo. The second clade consists of the tribes Menispermeae sensu DC. and Tiliacoreae Miers. All our analyses surprisingly recognized that tribe Menispermeae is not monophyletic unless tribe Tiliacoreae is included, suggesting that characters of cotyledon and stylar scar are very important for the infrafamilial classification, and that endosperm presence vs. absence was over-emphasized in traditionally tribal division of the family. Our topologies indicate a secondary loss of endosperm. The monophyly of two subtribes of the tribe Menispermeae, Stephaniinae and Cissampelinae, is supported by the cpDNA and ITS data, as well as by morphological characters, including aperture types and shapes, and colpal membrane features of pollen grains, and sepal number of male flowers. The Cocculinae was recognized as a paraphyletic group containing the remaining genera of the tribe Menispermeae.  相似文献   

4.
Eunicid annelids inhabit diverse marine habitats worldwide, have ecological and economic importance and have been pictured in the news as giant predator worms. They compose a traditional stable taxon recently supported as monophyletic but characterized by plesiomorphies. Most genera within the family have been recovered as paraphyletic in previous studies. We present a phylogenetic hypothesis for eunicid based on molecular (COI, 16S rDNA, 18S rDNA) and morphological data (213 characters), including an explicit attempt to account for serial homology. Eunicidae as well as monophyletic genera Marphysa sensu stricto and Lysidice is redefined based on synapomorphies. Nematonereis is synonymized to Lysidice. Leodice and Nicidion are resurrected to name monophyletic groups including species previously included in Eunice and Marphysa sensu lato. Traditional diagnostic characters such as the absence/presence of peristomial cirri, lateral antennae and branchiae are homoplasies and not informative at the generic level. Different coding of traditional characters (i.e. articulation of prostomial appendages) and novel characters of prostomial features and regionalization of the body support the monophyly of the family and genera level clades. Thus, the phylogenetic hypothesis presented here and the evolution of characters provided background information for taxonomic changes yielding evolutionary meaningful classification and diagnoses for the family and genera.  相似文献   

5.
We redescribe the South American genus Acanthaegilips Ashmead, 1897 and discuss its phylogenetic position within the Figitidae (sensu lata). The genus was originally placed in the Anacharitinae but shows affinities with both the Anacharitinae and the Aspiceratinae in the characters used currendy to separate figitid subfamilies. In a recent revision of the higher‐level classification of cynipoids, Acanthaegilips was separated from the remainder of the Anacharitinae and placed in a monotypic higher‐level taxon. We analyse the morphological differences between die Anacharitinae and Aspiceratinae and their bearing on the monophyly of the two subfamilies and the placement of Acanthaegilips. We conclude that, after removal of Seitneria and Paraegilips from the Anacharitinae, both subfamilies are well defined monophyletic groups and that Acanthaegilips belongs to the Anacharitinae, within which it forms a monophyletic group together with the South American genera Calofigites Kieffer, 1909 and Solenofigites Diaz, 1979.  相似文献   

6.
瑞香属和荛花属为瑞香科瑞香亚科的落叶或常绿灌木,中国西南部是瑞香属和荛花属的重要分化中心。全世界共有瑞香属95种、荛花属70种,中国分布有瑞香属52种、荛花属49种。瑞香属和荛花属的分类学研究一直存在不同程度的分歧。花盘形状和果实类型在传统分类中一直是区分瑞香属和荛花属的典型特征,而花盘形态和果实类型在2个属中存在交叉和过渡,部分植物分类学家根据这些特征将两个属进行过不同程度的归并。该研究采用数量分类法对瑞香属77种(变种)和荛花属62种(变种)植物,选取32个形态学性状进行聚类分析和主成分分析。结果表明:聚类分析和主成分分析均显示两属均未形成单系类群。在主成分分析中,前3个主成分分析的贡献值为35.56%,传统分类中用来区分两属的花盘形状、叶序及果实类型等特征对前3个主成分贡献相对较小,因此,传统分类学中对这两个属进行区分的性状并没有典型的分类学意义。同时,聚类图和主成分分析得到的散点图均不能将这两个属区分开来。数量分类研究结果显示两属植物存在明显的交叉,支持瑞香属和荛花属不是两个独立自然类群的观点。  相似文献   

7.
Orthoptera have been used for decades for numerous evolutionary questions but several of its constituent groups, notably crickets, still suffer from a lack of a robust phylogenetic hypothesis. We propose the first phylogenetic hypothesis for the evolution of crickets sensu lato, based on analysis of 205 species, representing 88% of the subfamilies and 71% tribes currently listed in the database Orthoptera Species File (OSF). We reconstructed parsimony, maximum likelihood and Bayesian phylogenies using fragments of 18S, 28SA, 28SD, H3, 12S, 16S, and cytb (~3600 bp). Our results support the monophyly of the cricket clade, and its subdivision into two clades: mole crickets and ant‐loving crickets on the one hand, and all the other crickets on the other (i.e. crickets sensu stricto). Crickets sensu stricto form seven monophyletic clades, which support part of the OSF families, “subfamily groups”, or subfamilies: the mole crickets (OSF Gryllotalpidae), the scaly crickets (OSF Mogoplistidae), and the true crickets (OSF Gryllidae) are recovered as monophyletic. Among the 22 sampled subfamilies, only six are monophyletic: Gryllotalpinae, Trigonidiinae, Pteroplistinae, Euscyrtinae, Oecanthinae, and Phaloriinae. Most of the 37 tribes sampled are para‐ or polyphyletic. We propose the best‐supported clades as backbones for future definitions of familial groups, validating some taxonomic hypotheses proposed in the past. These clades fit variously with the morphological characters used today to identify crickets. Our study emphasizes the utility of a classificatory system that accommodates diagnostic characters and monophyletic units of evolution. Moreover, the phylogenetic hypotheses proposed by the present study open new perspectives for further evolutionary research, especially on acoustic communication and biogeography.  相似文献   

8.
Eva Luegmayr 《Grana》2013,52(4-5):221-232
Pollen of 108 species out of 18 genera (from all tribes of the Old World Gesneriaceae [subf. Cyrtandroideae]) was examined using light, scanning and transmission electron microscopy. The pollen grains are small sized, isopolar and 3-colpate or 3-colporate. In equatorial view they are mostly spheroidal (rarely suboblate or oblate), in polar view circular or subangular. The most variable character is the exine structure and -sculpture. The tectum is perforate, microreticulate, coarsely reticulate or rugulate. Further important characters of the tectum are (a) the presence or absence of conical supratectate sculptural elements, and (b) the width of lumina being either equal or exhibiting different at the apo- and mesocolpium. Ten exine types are distinguished. Some genera and species can be well referred to a special exine type, e.g., Aeschynanthus, Epithema, Stauranthera grandiflora; in other genera several exine types occur, e.g., in the large and heterogeneous genus Didymocarpus. The pollen morphology of the two large subfamilies Cyrtandroideae and Gesnerioideae is compared.  相似文献   

9.
Pollen grains of the tribe Pavetteae (Rubiaceae, subfamily Ixoroideae) are examined using LM and SEM. Grains are 3‐ or 4‐colporate and (semi‐) tectate (in one Versteegia species atectate). Sexine patterns vary between perforate, microreticulate, reticulate, rugulate and striato‐reticulate. Supratectal elements are sometimes present. The variation in pollen morphology in the Pavetteae allows to recognize seven pollen types, the distribution of which is useful to evaluate generic delimitations and relationships within the tribe. Pollen characters corroborate the close relationships between the genera Coleactina, Dictyandra and Leptactina and between Homollea, Homolliella and Paracephaelis. All the genera of the tribe proved to be stenopalynous (the species examined possess the same pollen type), except Pavetta, Rutidea, Versteegia and Tarenna which are eurypalynous. In the huge genus Pavetta the existing infrageneric classification is supported pollen morphologically. Pollen morphology further indicates that the genus Tarenna is badly delimited and strongly in need of a revision. The small genus Versteegia is in need of further taxonomic and palynological study to understand the pollen morphological variation encountered here. At a higher rank, pollen morphology also does not contradict the recent division of the Pavetteae in the Ixoreae (a stenopalynous tribe with presumably primitive pollen) and the Pavetteae sensu stricto (eurypalynous).  相似文献   

10.
A comprehensive higher‐level phylogeny of diving beetles (Dytiscidae) based on larval characters is presented. Larval morphology and chaetotaxy of a broad range of genera and species was studied, covering all currently recognized subfamilies and tribes except for the small and geographically restricted Hydrodytinae, where the larva is unknown. The results suggest several significant conclusions with respect to the systematics of Dytiscidae including the following: monophyly of all currently recognized subfamilies, although Dytiscinae when considered in a broad context is rendered paraphyletic by Cybistrinae; currently recognized tribes are monophyletic except for Agabini, Hydroporini and Laccornellini; inter‐subfamily and inter‐tribe relationships generally show weak support, except for a few well supported clades; three distinct clades are recognized within Dytiscinae [Dytiscini sensu lato (i.e. including the genera Dytiscus Linnaeus and Hyderodes Hope), Hydaticini sensu lato, and Cybistrini]; and recognition of Pachydrini as a distinct tribe. Other less robust results include: Methlini sister to the rest of Hydroporinae; relative basal position of Laccornini, Hydrovatini and Laccornellini within Hydroporinae; close relationship of Agabinae and Copelatinae; Matinae nested deep within Dytiscidae, as sister to a large clade including Colymbetinae, Coptotominae, Lancetinae and Dytiscinae sensu lato; the sister‐group relationship of Agabetini and Laccophilini is confirmed. The results presented here are discussed and compared with previous phylogenetic hypotheses based on different datasets, and the evolution of some significant morphological features is discussed in light of the proposed phylogeny. All suprageneric taxa are diagnosed, including illustrations of all relevant synapomorphies, and a key to separate subfamilies and tribes is presented, both in traditional (paper) format and as an online Lucid interactive identification key.  相似文献   

11.
Phylogenetic analysis of the New World Ptininae (Coleoptera: Bostrichoidea)   总被引:2,自引:0,他引:2  
A phylogenetic analysis of the New World Ptininae (Anobiidae) was conducted with representatives of nine of ten New World genera, several Old World genera and seven more of the ten subfamilies of Anobiidae. One hundred and two characters (forty‐three multistate) from thirty‐four taxa were used. The single cladogram shows Ptininae as monophyletic and the sister group of the remaining Anobiidae, supporting their placement as subfamilies of a monophyletic Bostrichidae. Genus Niptus Boieldieu is polyphyletic supporting recognition of Pseudeurostus Heyden and the creation of a new genus to encompass the remaining New World species of Niptus. Flightlessness has evolved a minimum of three times within Ptininae and myrmecophily has probably evolved three times within just the New World taxa. The classifications of Ptininae and the remaining Anobiidae are examined and the evolution of feeding habits, myrmecophily and wing loss are discussed.  相似文献   

12.
The pollen morphology of Adenandra Willd. (Rutaceae: Diosminae) was investigated to determine its taxonomic significance. Pollen of 27 of the 30 infrageneric taxa (representing 16 of the 18 species) was investigated by LM, SEM and TEM. Adenandra differs from all other Diosminae in having 4-colporate rather than 3-colporate pollen grains. This supports the alleged monophyletic status of the genus. Exine morphology and structure, however, is extremely diverse considering the size of the genus, with eight distinct pollen types and four subtypes being discerned. In some members the grains have uniform macroreticulate, striate or striato-reticulate sculpturing, whereas in others the poles have striate, striato-reticulate or reticulate-perforate sculpturing with various types of reticulate or rugulate sculpturing at the mesocolpia. Taxonomic groupings revealed by the pollen characters suggest elationships between taxa that were not previously apparent. It is suggested that evolutionary diversification among species of Adenandra is often more strikingly reflected by pollen morphology than by macromorphology, hence the eurypalynous state of the genus.  相似文献   

13.
Örjan Nilsson 《Grana》2013,52(2-3):279-363
The pollen morphology of several genera in Portulacaceae is described. Particular attention has been paid to the genera of the subfamily Montioideae, as a stage of continued monographical studies. Among genera especially dealt with are Claytonia, Montia, Crunocallis, Naiocrene, Neopaxia, Mona, Maxia, Limnalsine, and Montiastrum. In the taxonomical treatment of these genera the pollen morphology has proved to afford many important additional characters.

The pollen grains of Claytonia are distinguished from those of the remainder in being 3-colpate. The grains of the Claytonia-type have many similarities with those of Lewisia, a genus of the subfamily Portulacoideae. The other genera of Montioideae have pantocolpate pollen grains. Among these genera several different pollen types are distinguished, chiefly with regard to the sexine structures and the aperture membranes. The Montiastrum-type is especially interesting, with tholate grains, a particular pollen type not met with in any other genus in the family. The pollen morphology of some genera in the Portulacoideae is also treated. In some species in Calandrina and Talinum pantotreme pollen grains are observed with apertures transitional between pori and colpi. The apertures of the pantotreme grains are arranged in characteristic patterns.

Particular attention has been given to the variation of the pollen morphological characters. This variation has been examined with regard to the differences between different populations of the same species as well as between different species. The greatest variation has been observed in the shape and size of the grains. The structure and sculpture and thickness of the sexine and the aperture membranes are less variable. Some polyploid taxa are connected with the occurrence of pollen grains with divergent and varying aperture numbers.

In a survey of the genera the taxonomical results of the investigation are presented with particular regard to the pollen morphology. The new genus, Maxia Ö. Nilss., is described. One new species, Montia clara Ö. Nilss., is described and some new combinations are made.

Pollen morphological diagnoses are given for 46 different taxa. The aperture conditions for 96 different species are presented.  相似文献   

14.
 Girella, Kyphosus, Scorpis, and some other perciform fishes have been regarded as being related to each other. Nelson (1994) recognized them as the subfamilies under the Kyphosidae, but he did not show any synapomorphic characters uniting them. Johnson and Fritzsche (1989) suggested that the perciform group characterized by RLA pattern 10, namely, Girellidae, Kyphosidae (not of Nelson, 1994), Scorpididae, Microcanthidae, Kuhliidae, Arripidae, Oplegnathidae, Terapontidae, and families of the Stromateoidei, form a monophyletic group. We estimated the phylogenetic relationships of fishes of the group to review monophyly of the Kyphosidae (sensu Nelson, 1994) by partially sequencing the mitochondrially encoded NADH dehydrogenase subunit 2 gene. Labracoglossa-Scorpis, Oplegnathus, Kyphosus, Kuhlia, Microcanthus, and Girella constituted a single clade with relatively high reliability values for both the neighbor-joining (NJ) and maximum-likelihood (ML) trees, but the monophyly of Kyphosidae (sensu Nelson, 1994) was not supported. The group characterized by RLA pattern 10 formed a monophyletic group both in the NJ and ML trees here; however, additional basal perciform taxa need to be analyzed to resolve it more clearly. Received: June 27, 2001 / Revised: September 29, 2001 / Accepted: October 28, 2001  相似文献   

15.
 Phylogenetic relationships in Rosaceae were studied using parsimony analysis of nucleotide sequence data from two regions of the chloroplast genome, the matK gene and the trnL-trnF region. As in a previously published phylogeny of Rosaceae based upon rbcL sequences, monophyletic groups were resolved that correspond, with some modifications, to subfamilies Maloideae and Rosoideae, but Spiraeoideae were polyphyletic. Three main lineages appear to have diverged early in the evolution of the family: 1) Rosoideae sensu stricto, including taxa with a base chromosome number of 7 (occasionally 8); 2) actinorhizal Rosaceae, a group of taxa that engage in symbiotic nitrogen fixation; and 3) the rest of the family. The spiraeoid genus Gillenia, not included in the rbcL study, was strongly supported as the sister taxon to Maloideae sensu lato. A New World origin of Maloideae is suggested. The position of the economically important genus Prunus and the status of subfamily Amygdaloideae remain unresolved. Received February 27, 2001 Accepted October 11, 2001  相似文献   

16.
为深入研究绣球属植物花粉形态的分类学价值和系统学意义,厘清绣球属与近缘属之间的系统发育关系,该文利用扫描电子显微镜(SEM,scanning electron microscope)对国产绣球属及其近缘属41种绣球花科(Hydrangeaceae)植物的花粉形态以及表面纹饰进行了观察。结果表明:绣球属及其近缘属的花粉为三孔沟;形状多数为长圆体形或近球体形;赤道面观为椭圆形或圆形;极面观多为圆形,少数为三角形或圆三角形。花粉外壁纹饰可分为网状和孔穴状。网眼内的三级纹饰可分为光滑和具颗粒状突起。根据花粉形状和外壁纹饰类型将上述物种划分为4个组,即花粉的形状为长圆体形,表面纹饰为孔穴纹饰;花粉的形状为长圆体形,表面纹饰为网状纹饰;花粉的形状为近球体形,表面纹饰为孔穴纹饰;花粉的形状为近球体形,表面纹饰为网状纹饰。以上可进一步细分为8个类型。上述表明花粉形态证据可为绣球属及其近缘属的属下分类和种间界定提供重要佐证;但结合前人的系统发育重建分析该属植物花粉形态的系统学意义相对有限,如花粉形态证据对于该属及其近缘种属系统发育树上大支的界定难以提供有力的证据。  相似文献   

17.
Pollen morphology of 15 species of Siphonoglossa and of two closely related groups was investigated. Two tribal-specific pollen types are found within Siphonoglossa sensu lato suggesting that the genus is artificial, composed of taxa belonging in several genera among two tribes (subtribes sensu Bremekamp) of Acanthaceae. Five taxa currently included in an informal subgeneric category of Siphonoglossa have tricolporate, prolate pollen (termed Type I) that is characteristic of Odontonemeae (= Odontoneminae, Justicieae). Pollen of the remaining taxa, belonging in two formal sections of the genus, are mostly 2-porate, bilateral (Type II) with a sexine sculpturing characteristic of Justicieae (= Justiciinae). Pollen of section Siphonoglossa is rather uniform, 2-porate, bilateral with lolongate pores, and seem to delimit a natural group. Taxa of section Pentaloba have a more heterogeneous pollen morphology, mostly 2-porate, bilateral with lalongate pores. Controversial aspects of the interpretation of pollen morphology in Justiciinae are presented and their relevance to this study are examined. Hypothetical trends in the evolution of pollen of Justiciinae are discussed and the application of pollen morphology to taxonomy of the genus is presented, including a recommendation for narrowing the generic concept of Siphonoglossa to the taxa of the type section.  相似文献   

18.
The family Cyprinidae is the largest freshwater fish group in the world, including over 200 genera and 2100 species. The phylogenetic relationships of major clades within this family are simply poorly understood, largely because of the overwhelming diversity of the group; however, several investigators have advanced different hypotheses of relationships that pre- and post-date the use of shared-derived characters as advocated through phylogenetic systematics. As expected, most previous investigations used morphological characters. Recently, mitochondrial DNA (mtDNA) sequences and combined morphological and mtDNA investigations have been used to explore and advance our understanding of species relationships and test monophyletic groupings. Limitations of these studies include limited taxon sampling and a strict reliance upon maternally inherited mtDNA variation. The present study is the first endeavor to recover the phylogenetic relationships of the 12 previously recognized monophyletic subfamilies within the Cyprinidae using newly sequenced nuclear DNA (nDNA) for over 50 species representing members of the different previously hypothesized subfamily and family groupings within the Cyprinidae and from other cypriniform families as outgroup taxa. Hypothesized phylogenetic relationships are constructed using maximum parsimony and Basyesian analyses of 1042 sites, of which 971 sites were variable and 790 were phylogenetically informative. Using other appropriate cypriniform taxa of the families Catostomidae (Myxocyprinus asiaticus), Gyrinocheilidae (Gyrinocheilus aymonieri), and Balitoridae (Nemacheilus sp. and Beaufortia kweichowensis) as outgroups, the Cyprinidae is resolved as a monophyletic group. Within the family the genera Raiamas, Barilius, Danio, and Rasbora, representing many of the tropical cyprinids, represent basal members of the family. All other species can be classified into variably supported and resolved monophyletic lineages, depending upon analysis, that are consistent with or correspond to Barbini and Leuciscini. The Barbini includes taxa traditionally aligned with the subfamily Cyprininae sensu previous morphological revisionary studies by Howes (Barbinae, Labeoninae, Cyprininae and Schizothoracinae). The Leuciscini includes six other subfamilies that are mainly divided into three separate lineages. The relationships among genera and subfamilies are discussed as well as the possible origins of major lineages.  相似文献   

19.
A parsimony‐based phylogenetic analysis of eighty‐three morphological characters of adults and immatures of seventy representatives of the tribes and subfamilies of Membracidae and two outgroup taxa was conducted to evaluate the status and relationships of these taxa. Centrotinae apparently gave rise to Nessorhinini and Oxyrhachini (both formerly treated as subfamilies, now syn.n. and syn.reinst., respectively, of Centrotinae). In contrast to previous analyses, a clade comprising Nicomiinae, Centronodinae, Centrodontinae, and the unplaced genera Holdgatiella Evans, Euwalkeria Goding and Antillotolania Ramos was recovered, but relationships within this clade were not well resolved. Nodonica bispinigera, gen.n. and sp.n., is described and placed in Centrodontini based on its sister‐group relationship to a clade comprising previously described genera of this tribe. Membracinae and Heteronotinae were consistently monophyletic. Neither Darninae nor Smiliinae, as previously defined, was monophyletic on the maximally parsimonious cladograms, but constraining both as monophyletic groups required only one additional step. The monophyly of Stegaspidinae, including Deiroderes Ramos (unplaced in Membracidae), was supported on some but not all equally parsimonious cladograms. More detailed analyses of individual subfamilies, as well as morphological data on the undescribed immatures of several membracid tribes and genera, will be needed to elucidate relationships among tribes and genera. A key to the subfamilies and tribes is provided.  相似文献   

20.
Pollen apertures were analyzed among the subfamilies Persoonioideae (seven genera; ca. 95 spp.), Sphalmioideae (one genus; one spp.), and Camarvonioideae (one genus; two spp.). Pollen was examined by light microscopy, cryosection, and transmission electron microscopy. Completed studies of pollen apertures among Grevilleoideae (ca. 40 genera; ca. 800 spp.), one of two major subfamilies in Proteaceae, provide a basis for comparison and analysis of aperture evolution among these subfamilies. Aperture characters within Persoonioideae are unique among Proteaceae examined to date. Five distinct aperture types occur among the three subfamilies, three of which (Placospermum, Persoonia, Bellendena) are restricted to Persoonioideae. Sphalmioideae and Camarvonioideae each exhibit a unique aperture organization. The most primitive aperture organization, and one unique to Placospermum, exhibits three main features: 1) a thin, granular endexine continuous around the grain; 2) a heterogeneous foot layer throughout the grain with increased disruptions at the aperture; and 3) only slight differences in exine characters between apertural and nonapertural regions. The Persoonia aperture type represents the next stage of aperture evolution which involves loss of endexine, restriction of a heterogeneous foot layer to the aperture, and marked differences in exine characters between apertural and nonapertural regions. The uniformly homogeneous ektexine in both nonapertural and aperture regions in Bellendena has developed independently. Sphalmium exhibits a primitively thin granular endexine though the restriction of endexine to the aperture is a derived condition. Carnarvonia exhibits several pollen characters also found among Grevilleoideae including: 1) a homogeneous nonapertural ektexine; 2) a slightly heterogeneous apertural ektexine; 3) a lamellate/granulate endexine organized into irregularly shaped “clumps” clustered around the aperture; and 4) a clear demarcation between apertural and nonapertural exine. These characters support the hypothesis that Carnarvonia may have diverged early from the pre-Grevilleoids.  相似文献   

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