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1.
Reproductive characteristics are important for defining taxonomic groups of filamentous Zygnematophyceae, but they have not been fully observed in the genus Zygogonium. Specimens of Z. ericetorum previously studied and used to clarify the generic concept lacked fertile material, which was obtained recently. This study illustrates for the first time, using color light microscopic and fluorescence images, a consequent conjugation stage in Z. ericetorum, including completely developed zygospores and purple cytoplasmic residue content left outside the zygospores, similar to aplanospore formation. Structures confirmed earlier reports and provided new observation informative regarding phylogenetically relevant reproductive characters of Z. ericetorum.  相似文献   

2.
Natural populations of Zygnema were collected from 80 stream sites across California, and eight species were identified and characterized morphologically. Generic and infrageneric concepts of Zygnema and Zygogonium were tested with cox3 and rbcL gene sequence analysis. Strains of Zygnema were positioned in a single monophyletic clade sister to Zygogonium tunetanum Gauth.‐Lièvre. In both the rbcL and cox3 phylogenies, strains of Zygnema formed two major clades. The first clade contained species that have zygospores with a blue‐colored mesospore or akinetes with a colorless mesospore. The second clade contained species that have a yellow or brown mesospore. The existing taxonomic concepts for Zygnema classification are not consistent with our molecular phylogeny and do not correspond to natural groups. We propose that mesospore color may be useful in the infrageneric classification of Zygnema. Newly described Zygnema aplanosporum sp. nov. and Zygnema californicum sp. nov. have zygospores with a blue mesospore formed in the conjugation tube and separated by a cellulosic sporangial wall. Z. aplanosporum also possessed a combination of vegetative and reproductive features characteristic of Zygogonium, such as presence of short branches, rhizoidal outgrowths, thickened vegetative cell walls, purple‐colored cell content, small compressed‐globular chloroplasts as well as predominant asexual reproduction. Z. aplanosporum and Z. californicum were deeply embedded in a larger clade of Zygnema both in rbcL and cox3 analyses. Based on our observations, there are no features or combination of features that separate Zygnema and Zygogonium. Therefore, we conclude that Zygogonium is probably a synonym of Zygnema.  相似文献   

3.
The phylogenetic relationships between western Palaearctic Zamenis and Rhinechis ratsnakes have been troubled, with recent estimates based on the supermatrix approach questioning their monophyly and providing contradictory results. In this study, we generated a comprehensive molecular data set for Zamenis and closely related ratsnakes to assess their phylogenetic and systematic relationships and infer their spatial and temporal modes of diversification. We obtained a fully resolved and well‐supported phylogeny, which is consistent across markers, taxon‐sets and phylogenetic methods. The close phylogenetic relationship between Rhinechis and Zamenis is well‐established. However, the early branching pattern within this clade, and the position of R. scalaris and Z. hohenackeri, remains poorly supported. The Persian ratsnake Z. persicus is sister to the Mediterranean species Z. situla, Z. longissimus and Z. lineatus, of which Z. situla is sister to a clade containing the latter two species. These results are consistent with a recent phylogenomic study on ratsnakes based on hundreds of loci. Whereas, topological tests based on our data and evidence from such phylogenomic study strongly rejected previous phylogenetic estimates based on the supermatrix approach and demonstrate that these “mega‐phylogenies”, with hundreds of taxa and high levels of missing data, have recovered inconsistent relationships with spurious nodal support. Biogeographical and molecular dating analyses suggest an origin of the ancestor of Rhinechis and Zamenis in the Aegean region with early cladogenesis during the Late Miocene associated with the Aegean arch formation and support a scenario of east‐to‐west diversification. Finally, while we have little morphological and phylogenetic evidence for the distinctiveness between Rhinechis and Zamenis, a classification of them in a single genus, and the designation of Zamenis scalaris (Schinz, 1822), reflects better their evolutionary relationships.  相似文献   

4.
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The Rufous‐headed Robin Larvivora ruficeps is one of the world's rarest and least known birds. We summarize the known records since it was first described in 1905 from Shaanxi Province, central China. All subsequent Chinese records are from seven adjacent localities in nearby Sichuan Province. We studied its phylogenetic position for the first time using mitochondrial and nuclear markers for all species of Larvivora and a broad selection of other species in the family Muscicapidae. Our results confirmed that L. ruficeps is appropriately placed in the genus Larvivora, and suggested that it is sister to the Rufous‐tailed Robin Larvivora sibilans, with these two forming a sister clade to a clade comprising both the Japanese Robin Larvivora akahige and Ryukyu Robin Larvivora komadori. Siberian Blue Robin Larvivora cyane and Indian Blue Robin Larvivora brunnea form the sister clade to the other Larvivora species. In contrast, song analyses indicated that the song of L. ruficeps is most similar to that of L. komadori, whereas the song of L. sibilans is relatively more similar to that of L. akahige, and songs of L. cyane and L. brunnea closely resemble each other. We used ecological niche modelling to estimate the suitable habitats of L. ruficeps based on the records from breeding grounds, suggesting that north and central Sichuan, south Gansu, south Shaanxi and south‐east Tibet are likely to contain the most suitable habitats for this species.  相似文献   

6.
The phylogenetic relationships among genera of the subfamily Ariantinae (Pulmonata, Helicidae), especially the sister‐group relationship of Cylindrus obtusus, were investigated with three mitochondrial (12S rRNA, 16S rRNA, Cytochrome c oxidase subunit I) and two nuclear marker genes (Histone H4 and H3). Within Ariantinae, C. obtusus stands out because of its aberrant cylindrical shell shape. Here, we present phylogenetic trees based on these five marker sequences and discuss the position of C. obtusus and phylogeographical scenarios in comparison with previously published results. Our results provide strong support for the sister‐group relationship between Cylindrus and Arianta confirming previous studies and imply that the split between the two genera is quite old. The tree reveals a phylogeographical pattern of Ariantinae with a well‐supported clade comprising the Balkan taxa which is the sister group to a clade with individuals from Alpine localities. Additional lineages representing samples from southern Alpine localities as well as from Slovakia split from more basal nodes, but their relationships are not clearly resolved. To achieve more definitive conclusions concerning the geographical origin of Ariantinae, still more sequence data are needed to obtain a tree with better resolution of basal nodes. The genetic data also provided new insights concerning the genus Cepaea, which was used as one of the outgroup taxa. Cepaea vindobonensis is only distantly related to Cepaea nemoralis and Cepaea hortensis, the latter two being more closely related to Eobania vermiculata. Thus, in our tree, the genus Cepaea is paraphyletic.  相似文献   

7.
Nuclear‐encoded SSU rDNA, chloroplast LSU rDNA, and rbcL genes were sequenced from 53 strains of conjugating green algae (Zygnematophyceae, Streptophyta) and used to analyze phylogenetic relationships in the traditional order Zygnematales. Analyses of a concatenated data set (5,220 nt) established 12 well‐supported clades in the order; seven of these constituted a superclade, termed “Zygnemataceae.” Together with genera (Zygnema, Mougeotia) traditionally placed in the family Zygnemataceae, the “Zygnemataceae” also included representatives of the genera Cylindrocystis and Mesotaenium, traditionally placed in the family Mesotaeniaceae. A synapomorphic amino acid replacement (codon 192, cysteine replaced by valine) in the LSU of RUBISCO characterized this superclade. The traditional genera Netrium, Cylindrocystis, and Mesotaenium were shown to be para‐ or polyphyletic, highlighting the inadequacy of phenotypic traits used to define these genera. Species of the traditional genus Netrium were resolved as three well‐supported clades each distinct in the number of chloroplasts per cell, their surface morphology (structure and arrangement of lamellae) and the position of the nucleus or nuclear behavior during cell division. Based on molecular phylogenetic analyses and synapomorphic phenotypic traits, the genus Netrium has been revised, and a new genus, Nucleotaenium gen. nov., was established. The genus Planotaenium, also formerly a part of Netrium, was identified as the sister group of the derived Roya/Desmidiales clade and thus occupies a key position in the evolutionary radiation leading to the most species‐rich group of streptophyte green algae.  相似文献   

8.
Peniculistoma mytili and Mytilophilus pacificae are placed in the pleuronematid scuticociliate family Peniculistomatidae based on morphology and ecological preference for the mantle cavity of mytiloid bivalves. We tested this placement with sequences of the small subunit rRNA (SSUrRNA) and cytochrome c oxidase subunit 1 (cox1) genes. These species are very closely related sister taxa with no distinct genetic difference in the SSUrRNA sequence but about 21% genetic difference for cox1, supporting their placement together but separation as distinct taxa. Using infection frequencies, M. pacificae, like its sister species P. mytili, does not interact with Ancistrum spp., co‐inhabitants of the mantle cavity. On the basis of these ecological similarities, the fossil record of host mussels, and features of morphology and stomatogenesis of these two ciliates, we argue that M. pacificae derived from a Peniculistoma‐like ancestor after divergence of the two host mussels. Our phylogenetic analyses of pleuronematid ciliates includes the SSUrRNA gene sequence of Sulcigera comosa, a Histiobalantium‐like ciliate from Lake Baikal. We conclude: (i) that the pleuronematids are a monophyletic group; (ii) that the genus Pleuronema is paraphyletic; and (iii) that S. comosa is a Histiobalantium species. We transfer S. comosa to Histiobalantium and propose a new combination Histiobalantium comosa n. comb.  相似文献   

9.
The monotypic genus Auxenochlorella with its type species A. protothecoides is so far only known from specific habitats such as the sap of several tree species. Several varieties were described according to physiological performances in culture on different organic substrates. However, two strains designated as Auxenochlorella were isolated from other habitats (an endosymbiont of Hydra viridis and an aquatic strain from an acidic volcano stream). We studied those isolates and compared them with six strains of Auxenochlorella belonging to different varieties. The integrative approach used in this study revealed that all strains showed similar morphology but differed in their SSU and ITS rDNA sequences. The Hydra endosymbiont formed a sister taxon to A. protothecoides, which included the varieties protothecoides, galactophila, and communis. The variety acidicola is not closely related to Auxenochlorella and represented its own lineage within the Trebouxiophyceae. In view of these results, we propose a new species of Auxenochlorella, A. symbiontica, for the Hydra symbiont, and a new genus Pumiliosphaera, with its type species, P. acidophila, for acidophilic strain. These results are supported by several compensatory base changes in the conserved region of ITS‐2 and ITS‐2 DNA barcodes.  相似文献   

10.
Photosynthetic euglenids acquired chloroplasts by secondary endosymbiosis, which resulted in changes to their mode of nutrition and affected the evolution of their morphological characters. Mapping morphological characters onto a reliable molecular tree could elucidate major trends of those changes. We analyzed nucleotide sequence data from regions of three nuclear‐encoded genes (nSSU, nLSU, hsp90), one chloroplast‐encoded gene (cpSSU) and one nuclear‐encoded chloroplast gene (psbO) to estimate phylogenetic relationships among 59 photosynthetic euglenid species. Our results were consistent with previous works; most genera were monophyletic, except for the polyphyletic genus Euglena, and the paraphyletic genus Phacus. We also analyzed character evolution in photosynthetic euglenids using our phylogenetic tree and eight morphological traits commonly used for generic and species diagnoses, including: characters corresponding to well‐defined clades, apomorphies like presence of lorica and mucilaginous stalks, and homoplastic characters like rigid cells and presence of large paramylon grains. This research indicated that pyrenoids were lost twice during the evolution of phototrophic euglenids, and that mucocysts, which only occur in the genus Euglena, evolved independently at least twice. In contrast, the evolution of cell shape and chloroplast morphology was difficult to elucidate, and could not be unambiguously reconstructed in our analyses.  相似文献   

11.
DNA sequence data were obtained for the gene encoding the large subunit of RUBISCO (rbcL) from 26 strains of Spirogyra and seven of Sirogonium, using as outgroups 10 genera in the Zygnematales and Desmidiales (Closterium, Cosmarium, Cylindrocystis, Gonatozygon, Mesotaenium, Netrium, Penium, Zygnema, Zygnemopsis, Zygogonium). Sequence data were analyzed using maximum parsimony (MP), maximum likelihood (ML), and Bayesian inference (BI), with bootstrap replication (MP, ML) and posterior probabilities (BI) as measures of support. MP, ML, and BI analyses of the rbcL data strongly support a single clade containing Spirogyra and Sirogonium. The Spirogyra taxa are monophyletic, with the exception of Spirogyra maxima (Hassall) Wittrock, which is nested within a clade with Sirogonium and shares with them the characters of loosely spiraled chloroplasts (<1 complete turn per cell) and anisogamy of gametangial cells; S. maxima differs from Sirogonium in displaying well‐defined conjugation tubes rather than a tubeless connection involving bending (genuflection) of filaments. The ML and BI analyses place this Sirogonium/Spirogyra maxima clade sister to the remaining Spirogyra. Morphological differences among strains of Spirogyra grouped together on the basis of rbcL data, including laboratory strains derived from clonal cultures (Spirogyra communis, S. pratensis), indicate that some characters (filament width, chloroplast number) used in the traditional taxonomy of this group are poor measures of species identity. However, some characters such as replicate end walls and loose spiraling of chloroplasts may be synapomorphies for Spirogyra clades.  相似文献   

12.
The Korean planthopper tribe Zoraidini is revised taxonomically. Five genera are recognized in the Korean fauna: Diostrombus Uhler, 1896, Losbanosia Muir, 1917, Pamendanga Distant, 1906, Shirakiana Metcalf, 1945, Zoraida Kirkaldy, 1900. Among them, the genus Shirakiana is recorded for the first time in Korea. Nine species, four of which are recognized new to Korea: S. infumata (Matsumura), Z. koannania Matsumura, Z. hubeiensis Chou et Huang, and Z. kuwayamae (Matsumura). Previous record of one species, Z. pterophoroides (Westwood, 1851), is removed from the list of Korean fauna because it was erroneously reported, based on a misidentification. All species are described and illustrated, and identification keys to genera and species are provided.  相似文献   

13.
Brown algae of the order Laminariales, commonly referred to as kelps, are the largest and most productive primary producers in the coastal inshore environment. The genus Ecklonia (Lessoniaceae, Phaeophyceae) consists of seven species with four species in the Northern Hemisphere and three in the Southern Hemisphere. It was recently transferred to the family Lessoniaceae based on phylogenetic analyses of nuclear and chloroplastic markers, though the type of the genus was not included and its relationship with allied genera Eckloniopsis and Eisenia remained unresolved. The present study is the first to produce a phylogeny focussed on the genus Ecklonia. It included sequences from nuclear, mitochondrial, and chloroplastic DNA, for most of the distribution range of the three current Southern Hemisphere species (Ecklonia radiata, Ecklonia maxima, and a sample of a putative Ecklonia brevipes specimen), sequences for East Asiatic species (Ecklonia cava, Ecklonia kurome, and Ecklonia stolonifera), as well as the closely related genera Eckloniopsis and Eisenia. Results confirmed E. radiata and E. maxima as two distinct species in South Africa, E. radiata as a single species throughout the Southern Hemisphere (in South Africa, Australia, and New Zealand) and East Asiatic species as a distinct lineage from the Southern Hemisphere clade. Results further pointed out a close sister relationship between Eckloniopsis radicosa and two Eisenia species (including the type species: Eisenia arborea) to the genus Ecklonia suggesting that the genera Eckloniopsis and Eisenia are superfluous.  相似文献   

14.
Strix (Strigidae) is a worldwide genus of 17 owl species typical of forested habitats, including Rusty‐barred Owls (S. hylophila), Chaco Owls (S. chacoensis), and Rufous‐legged Owls (S. rufipes) in South America. These species are distributed allopatrically, but the ecological traits that determine their distributions remain largely unknown and their phylogenetic relationships are unclear. We used species distribution models (SDMs) to identify variables explaining their distribution patterns and test hypotheses about ecological divergence and conservatism based on niche overlap analysis. For Rusty‐barred Owls and Chaco Owls, climatic factors related to temperature played a major role, whereas a rainfall variable was more important for Rufous‐legged Owls. When niche overlaps were compared, accounting for regional similarities in the habitat available to each species, an ecological niche divergence process was supported for Chaco Owl‐Rusty‐barred Owl and Chaco Owl‐Rufous‐legged Owl, whereas a niche conservatism process was supported for Rusty‐barred Owl‐Rufous‐legged Owl. Different ecological requirements support current species delimitation, but they are in disagreement with the two main hypotheses currently envisaged about their phylogenetic relationships (Chaco Owls as the sister taxa of either Rufous‐legged Owls or Rusty‐barred Owls) and support a new phylogenetic hypothesis (Rufous‐legged Owls as sister taxa of Rusty‐barred Owls). Our findings suggest that speciation of Rusty‐barred Owls and Rufous‐legged Owls was a vicariant event resulting from Atlantic marine transgressions in southern South America in the Miocene, but their niche was conserved because habitat changed little in their respective ranges. In contrast, Chaco Owls diverged ecologically from the other two species as a result of their adaptations to the habitat they currently occupy. Ecological and historical approaches in biogeography can be embedded to explain distribution patterns, and results provided by SDMs can be used to infer historical and ecological processes in an integrative way.  相似文献   

15.
The genus Esoptrodinium Javornický consists of freshwater, athecate dinoflagellates with an incomplete cingulum. Strains isolated thus far feed on microalgae and most possess obvious pigmented chloroplasts, suggesting mixotrophy. However, some geographic isolates lack obvious pigmented chloroplasts. The purpose of this study was to comparatively examine this difference and the associated potential for mixotrophy among different isolates of Esoptrodinium. All isolates phagocytized prey cells through an unusual hatch‐like peduncle located on the ventral episome, and were capable of ingesting various protist taxa. All Esoptrodinium isolates required both food and light to grow. However, only the tested strain with visible pigmented chloroplasts benefited from light in terms of increased biomass (phototrophy). Isolates lacking obvious chloroplasts received no biomass benefit from light, but nevertheless required light for sustained growth (i.e., photoobligate, but not phototrophic). Isolates with visible chloroplasts exhibited chlorophyll autofluorescence and formed a monophyletic psbA gene clade that suggested Esoptrodinium possesses inherited, peridinoid‐type plastids. One isolate with cryptic, barely visible plastids lacked detectable chlorophyll and exhibited an apparent loss‐of‐function mutation in psbA, indicating the presence of nonphotosynthetic plastids. The other isolate that lacked visible chloroplasts lacked both detectable chlorophyll and an amplifiable psbA sequence. The results demonstrate mixotrophy quantitatively for the first time in a freshwater dinoflagellate, as well as apparent within‐clade loss of phototrophy along with a correlated mutation sufficient to explain that phenotype. Phototrophy is a variable trait in Esoptrodinium; further study is required to determine if this represents an inter‐ or intraspecific (allelic) characteristic in this taxon.  相似文献   

16.
The current study focuses on four species from the primarily marine diatom genus Craspedostauros that were observed growing attached to numerous sea turtles and sea turtle‐associated barnacles from Croatia and South Africa. Three of the examined taxa, C. danayanus sp. nov., C. legouvelloanus sp. nov., and C. macewanii sp. nov., are described based on morphological and, whenever possible, molecular characteristics. The new taxa exhibit characters not previously observed in other members of the genus, such as the presence of more than two rows of cribrate areolae on the girdle bands, shallow perforated septa, and a complete reduction of the stauros. The fourth species, C. alatus, itself recently described from museum sea turtle specimens, is reported for the first time from loggerhead sea turtles rescued in Europe. A 3‐gene phylogenetic analysis including DNA sequence data for three sea turtle‐associated Craspedostauros species and other marine and epizoic diatom taxa indicated that Craspedostauros is monophyletic and sister to Achnanthes. This study, being based on a large number of samples and animal specimens analyzed and using different preservation and processing methods, provides new insights into the ecology and biogeography of the genus and sheds light on the level of intimacy and permanency in the host–epibiont interaction within the epizoic Craspedostauros species.  相似文献   

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1. In extremely acid mining lakes, benthic filamentous green algae (Zygnemataceae, Chlorophyta) thrive as effective competitors for limited carbon (C). These algae could supply C for microbial‐mediated benthic alkalinity generation. However, biomass, productivity and impact of the acidobiontic filamentous green algae at pH ≤3 have not previously been determined. 2. Periphytic filamentous green algae was mapped by harvesting their biomass from 85 1 × 1 m quadrats in mining lake Grünewalder Lauch. Zygogonium ericetorum colonised water depths between 1.6 and 10.5 m covering 88% of total area. Biomass peaked at 5–6 m depth. Total Zygogonium biomass amounted to 72.2 t dry weight for the whole lake (0.94 km2), which corresponds to 16.1 t C and the accumulation of primary production from 2.2 years. 3. Growth of Zygogonium is moderately N, C and extremely P deficient, and seriously stressed by high rates of Fe deposition during summer. Consequently, net primary production (NPP) of Zygogonium, calculated from measured photosynthesis versus irradiance characteristics and calculated underwater irradiance (0.13 g C m?2 year?1) and in situ oxygen measurements (7.8 g C m?2 year?1), corresponds to only 0.3% and 18.1% of pelagic NPP. 4. Neither pelagic nor benthic Zygogonium primary production can supply enough C for efficient acidity removal. However, at rates of benthic NPP in summer of 21.4 mg C m?2 day?1, Zygogonium contributed 26% of the C equivalents to remove acidity associated with ferric iron, contributing at least seasonally to efficient alkalinity generation.  相似文献   

20.
Anomaluroidea, commonly known as the “scaly‐tailed squirrels,” are an emblematic group of tropical African mammals that includes gliding forms. The family Anomaluridae was until recently represented by three genera: the flying scaly‐tailed squirrels (Anomalurus), the flying mouse (Idiurus) and the flightless scaly‐tailed squirrels (Zenkerella). Idiurus and Zenkerella have long been grouped into the Zenkerellinae subfamily, and Zenkerella was interpreted as a rare case of evolutionary reversal to non‐gliding lifestyle. Recent studies have demonstrated that Zenkerella is sister to all other modern anomalurids, and represents in fact the monogeneric family Zenkerellidae. The Anomalurus genus was split into Anomalurus and Anomalurops, but no study has ever considered all Anomalurus species together in a phylogeny to test the status of Anomalurops. Here, we used mitogenomic next‐generation sequencing to infer the phylogenetic relationships among all extant anomalurids and to estimate their divergence ages. We found that the arboreal Zenkerella is the sister group of all extant gliding anomalurids (Idiurus and Anomalurus). We confirmed that Anomaluroidea only evolved the gliding adaptation once. A comparison based on morphological traits indicates that Zenkerella harbours several unique morphological features. We propose new morphological characters for the novel classification of modern Anomaluroidea, which includes the families Zenkerellidae and Anomaluridae. Using different calibration schemes, we demonstrated that classical dating methods relying only on mitogenomes provide rather young Miocene estimates between Zenkerellidae and the Anomaluridae. The use of published nuclear genes, internal calibrations and tip dating converged towards an Eocene split between gliding and non‐gliding scaly‐tailed squirrels, which is in agreement with the African fossil record. Finally, we provide the first exhaustive species‐level molecular phylogenetic inference for the genus Anomalurus. We found that Anomalurus beecrofti is the sister group of all other species of Anomalurus and branched off during the Miocene.  相似文献   

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