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1.
Characeae (Charophyceae, Charophyta) contains two tribes with six genera: tribe Chareae with four genera and tribe Nitelleae, which includes Tolypella and Nitella. This paper uses molecular and morphological data to elucidate the phylogeny of Tolypella species in North America. In the most comprehensive taxonomic treatment of Characeae, 16 Tolypella species worldwide were subsumed into two species, T. intricata and T. nidifica, in two sections, Rothia and Tolypella respectively. It was further suggested that Tolypella might be a derived group within Nitella. In this investigation into species diversity and relationships in North American Tolypella, sequence data from the plastid genes atpB, psbC, and rbcL were assembled for a broad range of charophycean and land plant taxa. Molecular data were used in conjunction with morphology to test monophyly of the genus and species within it. Phylogenetic analyses of the sequence data showed that Characeae is monophyletic but that Nitelleae is paraphyletic with Tolypella sister to a monophyletic Nitella + Chareae. The results also supported the monophyly of Tolypella and the sections Rothia and Tolypella. Morphologically defined species were supported as clades with little or no DNA sequence differences. In addition, molecular data revealed several lineages and a new species (T. ramosissima sp. nov.), which suggests greater species diversity in Tolypella than previously recognized.  相似文献   

2.
Extant genera of Characeae have been assigned to two tribes: Chareae (Chara, Lamprothamnium, Nitellopsis, and Lychnothamnus) and Nitelleae (Nitella and Tolypella), based on morphology of the thallus and reproductive structures. Character analysis of fossil and extant oogonia suggest that Tolypella is polyphyletic, the genus comprising two sections, one in each of the two tribes. Eleven morphological characters and sequence data for the Rubisco large subunit (rbcL) were used to reconstruct the phylogeny of genera, including the two sections of Tolypella. Parsimony analysis of the rbcL data, with all positions and changes weighted equally, strongly supports the monophyly of the Characeae. The two Tolypella sections form a robust monophyletic group basal to the family. Transversion weighting yielded the same tree but with a paraphyletic Tolypella. The rbcL data strongly support monophyly of tribe Chareae but tribe Nitelleae is paraphyletic. Parsimony analysis of morphological data produced one unrooted tree consistent with monophyly of the two tribes; on this tree the Tolypella sections were paraphyletic. Combining morphological with rbcL data did not change the results derived from rbcL sequences alone. The rbcL data support the monophyly of the Characeae and Coleochaete, which together form a monophyletic sister group to embryophytes.  相似文献   

3.
We present the first experimental results on salinity tolerance and regulation mechanisms in the genus Tolypella. The two species investigated, T. nidifica and T. glomerata, regulate turgor pressure with almost complete effectiveness by adjustment of K+ and CT concentrations. Sucrose is also involved. The mechanism is basically identical to the mechanism of turgor pressure regulation previously identified in representatives of the genera Chara and Lamprothamnium. Since Chara and Lamprothamnium on the one hand and Tolypella on the other belong to different phylogenetic branches that separated early in the geological history of the Characeae, the K+ regulation mechanism can be assumed to represent an ancient pattern derived from a salt-tolerant common ancestor. Furthermore, our experiments provide evidence that salinity is a limiting factor for fertility in both T. nidifica and T. glomerata. Although the onset of gametangia covers the whole range of salinities tested here (0–29 psu), 12psu was the inhibitory level for the formation of mature oospores. Fertilization is probably disturbed by an increase in salinity. An inability to reproduce sexually under euryhaline conditions could explain why the distribution of the two species is restricted to oligo- and mesohaline environments, despite the wide range of salinity tolerance of their vegetative apparatus.  相似文献   

4.
Fourteen species of Characeae were analyzed for their free amino acids. This study, in combination with previous results (Sakanoet al., 1984) showed that all the species that belong to the generaChara (6 species),Lamprothamnium (1 species),Nitellopsis (1 species),Lychnothammus (1 species) and 5Nitella species of the members of the subsectionAnarthrodactylae contained a large amount of isoasparagine. In contrast, no isoasparagine was found in the species belonging toTolypella (3 species) and otherNitella (7 species). Presence of isoasparagine in some species of Characeae (N. flexillis andNitellopsis obtusa) was found to be independent of their localities (Japan, Canada and England). Species lacking isoasparagine (N. oligogyra and N. axilliformis) did not produce isoasparagine even under the condition that induced a great increase of this amino acid in the species that contained it (C. corallina andN. flexilis). These results indicate that isoasparagine is a distinct taxonomic marker and suggest that theNitella species of the subsectionAnarthrodactylae are the most primitive group inNitelleae in that they share synthesis and accumulation of isoasparagine withChareae and, hence, support the view (Kasaki, 1964) that the subsection may be treated as an independent genus.  相似文献   

5.
Thirteen species of Characeae were analyzed for their free amino acid contents. Large amounts of isoasparagine, accounting for 10 to 50% of the total free amino acids, were found in extracts fromChara (5 species including one unidentified),Nitellopsis (1 species), andLamprothamnium (1 species). In contrast, no isoasparagine was detected inNitella (5 species) andTolypella (1 species), except forN. flexilis in which as much as 40% of the free amino acids was isoasparagine. Other major amino acids found in the tested materials were Ala, Asp, Glu and Gln.  相似文献   

6.
Leaf compressions, previously assigned to Rhamnus marginatus Lesquereux, were collected from the Middle Eocene Claiborne Formation of western Kentucky and Tennessee. The leaf architecture and cuticular features of over 40 compressions were carefully examined and compared to those of many extant species of Rhamnaceae and related families as well as fossil specimens previously assigned to this taxon. This leaf type appears to belong to the Rhamnaceae, however, it conforms more closely to species of several genera in the tribe Zizypheae than to those of Rhamnus or other genera in the tribe Rhamneae. Confident assignment to any specific genus within this complex of genera cannot be made on the basis of leaf characteristics alone and would require discovery and analysis of additional vegetative and reproductive organs. Because this fossil leaf form cannot be confidently assigned to any modern genus and earlier classifications appear to be improper, this leaf type has been reassigned to the taxon Berhamniphyllum claibornense gen. et sp. nov. The transfer of this leaf form at the tribe level reaffirms the need for close examination of taxonomic determinations made by early workers.  相似文献   

7.
The horned soldier aphids of the Cerataphidini, unlike most social insects that reside in nests, live on the open surface of plants. The lack of a nest and other obvious ecological correlates makes it unclear why secondary-host soldiers might have evolved. Here I present a molecular phylogenetic analysis of 32 species of the Cerataphidini, including 10 species from the genera Ceratovacuna and Pseudoregma that produce horned soldiers. The phylogeny suggests that horned soldiers evolved once and were lost once or twice. Most horned soldiers are a morphologically specialized caste and two species that have unspecialized soldiers are independently derived from species with specialized castes. The genus Ceratovacuna appears to have undergone a relatively rapid radiation. Mapping secondary-host plants and geographic ranges onto the phylogeny suggests that bamboos were the ancestral secondary-host plants and that the Asian tropics and subtropics were the ancestral geographic regions for the genera Astegopteryx, Ceratoglyphina, Ceratovacuna Chaitoregma, and Pseudoregma and possibly for the entire tribe. There is evidence for vicariant events that separate the tropical and subtropical lineages in all of the major lineages of the tribe and for dispersal of some lineages. Based on these results, I present hypotheses for the causes and consequences of horned-soldier evolution.  相似文献   

8.
A wide range of transitional forms of granular interstitia from simple to complex and from random to ordered occur in the pollen of the subfamily Papilionoideae. Three main types are described: 1) large, widely spaced irregular granules (Type A); 2) densely packed groups of columellae and granules (Type B); and 3) a mass of more or less disorganized granules (Type C). In the genus Calopogonium (tribe Phaseoleae) all three types have been found in different species. Two of the types have been found in different species of the genus Psoralea (tribe Psoraleeae). Granular structures so far occur in six tribes: Desmodieae, Indigofereae, Loteae, Phaseoleae, Psoraleeae, and Vicieae. All of the tribes are regarded as being evolutionarily advanced in both macro and micro characters and many, but not all, show specialized pollen characters. It is concluded that the granular interstitium is a derived structure in papilionoid legumes.  相似文献   

9.
The water scavenger beetle tribe Hydrobiusini contains 47 species in eight genera distributed worldwide. Most species of the tribe are aquatic, although several species are known to occur in waterfalls or tree mosses. Some members of the tribe are known to communicate via underwater stridulation. While recent morphological and molecular‐based phylogenies have affirmed the monophyly of the tribe as currently circumscribed, doubts remain about the monophyly of included genera. Here we use morphological and molecular data to infer a species‐level phylogeny of the Hydrobiusini. The monophyly of the tribe is decisively supported, as is the monophyly of most genera. The genus Hydrobius was found to be polyphyletic, and as a result the genus Limnohydrobius stat. rev. is removed from synonymy with Hydrobius, yielding three new combinations: L. melaenus comb.n. , L. orientalis comb.n. , and L. tumbius comb.n. Recent changes to the species‐level taxonomy of Hydrobius are reviewed. The morphology of the stridulatory apparatus has undergone a single remarkable transformation within the lineage, from a simple, unmodified pars stridens to one that is highly organized and complex. We present an updated key to genera, revised generic diagnoses and a list of the known distributions for all species within the tribe.  相似文献   

10.
The pollen morphology of 9 of the 11 genera of the tribe Swartzieae is described together with that of Holocalyx and Cyathostegia, two genera recently removed from the tribe based on macromorphology. The pollen is small, spheroidal to subprolate, primarily tricolporate with a perforate tectum and generally typical of the Leguminosae. Nonetheless, many of the genera have distinctive pollen morphology. Baphiopsis is 6-colporate. The genera Harleyodendron, Lecointea and one species of Exostyles have supratectal spinules. Bocoa viridiflora has striate/rugulate ornamentation very distinct from the other species of the genus Bocoa. The exine stratification is varied but Candolleodendron has a very thick endexine and narrow foot layer. The pollen of African taxa does not differ significantly from that of South American taxa. Pollen morphology does not clarify the taxonomic relationships of the tribe and provides little evidence to assist in positioning Holocalyx and Cyathostegia.  相似文献   

11.
A new genus and species Gordoniopsis polysperma and two new species of Gordonia (Gordonieae, Camellioideae, Theaceae) are described based on fossil fruit and seed remains. These specimens are part of a large flora consisting of various plant organs from the middle Eocene Claiborne Formation in western Kentucky and Tennessee. Gordoniopsis is a five-valved loculicidally dehiscent capsule similar to capsules of Gordonia but differing in having unwinged seeds and a greater number of seeds per locule. The two Gordonia species are among the earliest unequivocal records of the genus and two of only four fossil Gordonia species known with in situ seeds. Two extinct genera, Gordoniopsis and Andrewsiocarpon, and the extant genus Gordonia in the tribe Gordonieae are known from the middle Eocene Claiborne flora, suggesting an early radiation within the tribe. Based on a survey of Recent fruits and seeds we concur with Keng's proposal to merge Laplacea with Gordonia.  相似文献   

12.
A comparative study was made of the gross morphology, fine venation and cuticular features of Leitneria fioridana Chapman, the single living representative of the order Leitneriales and Leitneria eocenica (Berry) Brown, presumbaly a related fossil species. In addition to the type material, newly collected fossil specimens were investigated from clay pits in the Middle Eocene, Claiborne Formation, of western Tennessee and Kentucky. Foliate stipules attached to the petioles of several specimens suggest the assignment of this fossil leaf type to the genus Leitneria is incorrect. The nature of the gross morphology, fine venation and cuticular features confirms the misidentification. Previously, various specimens of this fossil leaf type have been placed in eight species of seven genera in seven families of six angiosperm orders, none of which are correct systematically. The gross morphology, venation and cuticular characters of the fossil leaf are distributed among a few extant South American genera of arborescent Rubiaceae. The fossil is an extinct rubiaceous leaf type which cannot be placed within a single modern subfamily, tribe or genus of the family. The organ genus, Paleorubiaceophyllum is proposed for these leaves. Three varieties of a single fossil species, P. eocenicum, are recognized. One variety with epidermal cells nearly twice the size of the others may represent a polyploid population.  相似文献   

13.
本文就科昆虫的起源,各亚科、族及属的分布特点进行了分析和总结;并根据各属的世界分布情况,将其分为8种类型。文中还就中国科昆虫的地理分布及特点作了初步的探讨,结果表明:在我国已知的2亚科4族20个属中,东洋区分布的有10个属,其中有3个属仅分布于我国;古北区分布的有1个属;东洋-古北区分布的有3个属;东洋-新北区分布的有1个属;东洋-古北-新北区分布的有4个属;东洋-古北-新北-非洲区分布的有1个属。此外,科昆虫在中国的一个主要分布特点就是多数种类集中分布于华中区、华南区和西南区;而华中区则很可能是科种类的分化中心,并以此为中心向其他区扩散。  相似文献   

14.
A total of 56 morphological characters were analyzed for 53 cirrospiline species that represent all of the 17 described genera of the tribe. The other taxa of the Eulophinae included in the analysis were six species of six representative genera in the tribe Eulophini, a species of Elasmus (the only genus comprising the tribe Elasmini), and a species of Trichospilus (unplaced). Trichospilus and two of the six genera of Eulophini examined were placed within Cirrospilini. Monophyly of Cirrospilini (when these two genera of Eulophini and Trichospilus are included) and of the cirrospiline genera for which more than one species were examined was supported, but the relationships between the genera were poorly resolved. An exception was Cirrospilus, the largest genus in the Cirrospilini, monophyly of which was not supported to any extent.  相似文献   

15.
The Juglandaceae (walnut family) has an excellent fossil record of various organs extending back to the earliest Tertiary. Several genera which today are restricted to isolated geographic regions were widespread in the Northern Hemisphere during the Tertiary. This paper focuses upon the fossil record of the Pterocarya alliance of the subfamily Juglandoideae, tribe Juglandeae. The Pterocarya alliance includes only two modern genera, Pterocarya (five species) and Cyclocarya (one species), both restricted to Eurasia. Paleogene sediments of the Rocky Mountain Region have yielded three genera and four species referable to the Pterocarya alliance: Cyclocarya (two species), Pterocarya, and a new genus, Polyptera. Although three of the four Paleogene species described here are attributed to present day genera, each represents an extinct form, which cannot be accommodated by any single living species. These fossils, reviewed with other published reports, indicate that the Pterocarya alliance, like the Engelhardia alliance of the same family, was more diverse and much more widespread geographically in the Tertiary than it is today.  相似文献   

16.
In Nitella flexilis, a species belonging to the section Anarthrodactylaeof the genus Nitella (Characeae), some mature cells, with theexception of those of the nodal complex and the rhizoid, shownumerous spherical vacuoles occupying the entire central regionof the cell. These vacuoles are fairly uniform in size measuring30–40 µm in diameter. Evidence is presented frominvestigations with the light and electron microscopes suggestingthat some mature cells of a certain group of Nitella speciesmay not have a huge central vacuole. Vacuolation in young cellsof the apex apparently begins by progressive dilation of theendoplasmic reticulum. The Golgi complex may also be involvedin vacuolation. The necessity for re-examination of certainbiological activities in the giant internode cell is explored.  相似文献   

17.
The series Gymnobasalia, a sharply differentiated subgeneric complex within the genus Chara, consists of at least seven morphologically distinct species. All seven species are reproductively isolated from one another. No evidence of even limited hybridization between the seven was encountered. The two dioecious members of the complex occupy restricted and, possibly partially overlapping ranges in South America. Monoecious members are in general more widely distributed but still appear to have originated in Central or South America. The holotype of C. zeylanica Klein ex Willdenow was examined and found to be tetrascutate. For the abundant and widely distributed monoecious-conjoined, octoscutate member of the complex, previously shown to be distinct from C. zeylanica, the earlier name C. haitensis Turpin is here validated. Chara foliolosa Muhl. ex Willdenow is considered conspecific with, but to hold priority over, C. sejuncta Braun.  相似文献   

18.
A survey of the three-dimensional organization of stamen vasculature in 100 genera and over 350 species of Araceae was made using clearings. The Araceae exhibit highly varied stamen vasculature, with three main patterns: 1) vascular bundles unbranched, 1–3 per stamen, 2) forked bundles in some or all stamens, 3) anastomosing vascular systems with several to many bundles entering a single stamen. Three major groups of taxa in the family can be recognized on the basis of their predominant pattern of stamen vasculature. Virtually all genera with bisexual flowers (most Pothoideae, Monsteroideae, Calloideae, Lasieae) have unbranched bundles, one per stamen, except two to three in some species of Holochlamys, Spathiphyllum, and Scindapsus. Forked stamen bundles are virtually restricted to and occur nearly throughout the monoecious Lasioideae, Philodendroideae, Colocasioideae and among certain Aroideae (sensu Engler), including tribes Arophyteae, Spathicarpeae (Asterostigmateae) and Protareae. No forked bundles were found in tribe Areae (Aroideae), except Theriophonum indicum or any Araceae with bisexual flowers, except two species of Cyrtosperma. Anastomosing systems are virtually limited to members of tribe Areae with larger stamens, such as Arum, Helicodiceros, Eminium and Dracunculus species. A similar pattern occurs in some Amorphophallus, but other patterns occur as well. The distributions of forked bundles and anastomosing systems in the family are notable because they are both highly congruent with Philodendroideae-Colocasioideae, and Aroideae, respectively, in Grayum's new system for the family. Virtually all of the genera with forked bundles are grouped together in the Philodendroideae-Colocasioideae. All of the genera with anastomosing systems are in the Areae, including the complex and variable Amorphophallus, which has an uncertain systematic placement.  相似文献   

19.
Recent questions concerning the taxonomic status of the diatom genus Gomphoneis Cleve have prompted critical examination of the valvar morphology of a species originally included in the genus. Light and electron microscopic observations on G. mammilla (Ehr.) Cl. show that the characteristics put forth by Cleve to delineate the genus are present in this taxon. Striae composed of two rows of simple areolae located in depressions on the valve and longitudinal lines formed by a broad internal axial plate were observed in G. mammilla. The presence of two apical spines on the headpole and the structure of a bilobed apical pore field located at the footpole are described, in addition to other valve features. Valve morphology of G. mammilla is compared with that of doubly-punctate Gomphonema species with the result that we recommend the two genera remain separate.  相似文献   

20.
Summary This article gives a survey of nucleus-associated structures and inclusions in a diverse range of characean algae includingChara braunii Gm.,Chara corallina Klein ex Willd., em. R.D.W.,Nitella cristata A.Br., em. R.D.W.,Nitella flexilis (L.) Ag.,Nitella furcata (Roxb. ex Bruz.) Ag. em. R.D.W.,Nitella hyalina (DC.) Ag.,Nitella pseudoflabellata A.Br., em. R.D.W.,Nitella pseudoflabellata var.imperialis T.F.A.,Nitella translucens var.axillaris (A.Br.) R.D.W. andNitellopsis obtusa (Desv. in Lois.) J.Gr. Lampbrushchromosome-like structures were found in nuclei ofNitella flexilis andNitellopsis obtusa and seem to be involved in the distribution of genetic material during nuclear fragmentation. Intranuclear tubular crystals of unknown protein composition were present in all species, especially in young, elongating cells, and could be important for establishing the main axis of the nuclei. Spindle-shaped protein crystals that originate in the nucleus and are released into the cytoplasm upon nuclear degeneration were observed in branchlet internodal cells of one population ofNitella flexilis. Perinuclear microtubules were present in all species, but perinuclear actin fibrils were hitherto only found in mostNitella species and inNitellopsis obtusa. None of these nucleus-associated structures seems to be responsible for the formation of constrictions leading to nuclear fragmentation. These constrictions were perpendicular to the main axis of the nucleus and symmetrical in theNitella species but asymmetric inC. braunii, C. corallina, and inNitellopsis obtusa. Statistical analysis of nuclear size, number and constriction sites indicate that fragmentation is a nonsynchronous process independent of the light-dark cycle.Abbreviations CLSM confocal laser scanning microscopy - DAPI 4,6-diamidino-2-phenylindole - DIC Nomarski differential interference contrast - LCLS lampbrush chromosome-like structure(s) Dedicated to Professor Walter Gustav Url on the occasion of his 70th birthday  相似文献   

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