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A new species of the holopodid genus Cyathidium was found on rocks off Grande Comore in a depth of around 200 m. Based on external morphology of resting animals, the new species Cyathidium plantei sp. n is described, with emphasis on comparison to the only other extant species ( C. foresti ) as well as to the four extinct representatives of the genus. Concerning morphological characters, the new species is almost identical to the Cretaceous C. depressum . A cladistic analysis of the entire family, including the genus Holopus, shares a peculiar pattern of bending of the arms, which in principle is an apomorphic character of the family and in detail shows variations within the family. In addition, stratigraphic data are used for the determination of the evolutionary direction. This analysis reveals that the two recent species are closely related to each other, and to the fossil C. depressum . from which the entire family is probably derived.  相似文献   

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Most protozoans that have been cultivated recently from high salinity waters appear to be obligate halophiles. Phylogenetic analyses indicate that these species mostly represent independent lineages. Here, we report the cultivation, morphological characterization, and phylogenetic analysis of two strains (XLG1 and HLM‐8) of a new extremely halotolerant heterolobosean amoeboflagellate. This species is closely related to the obligate halophiles Tulamoeba peronaphora and Pleurostomum flabellatum, and more specifically to the former. Like Tulamoeba, the new species has a monopodial limax amoeba stage, however, its cyst stage lacks an intrusive pore plug. The flagellate stage bears a combination of a planar spiral feeding apparatus and unequal heterodynamic flagella that discriminates it from described Pleurostomum species. Strain XLG1 grows at salinities from 35‰ to 225‰. This degree of halotolerance is uncommon in protozoa, as most species showing growth in seawater are unable to grow at 200‰ salinity. The unrelatedness of most halophilic protozoa suggested that independent colonization of the hypersaline environment is more common than speciation within it. However, this study supports the idea that the Tulamoeba–Pleurostomum clade underwent an adaptive radiation within the hypersaline environment. A new species Tulamoeba bucina n. sp. is described, with Tulamoebidae n. fam. proposed for the Tulamoeba–Pleurostomum clade.  相似文献   

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We analysed 87 species of Onosma (Boraginaceae) from throughout its distribution range to investigate its evolutionary history. Using nrDNA ITS and two plastid (rpl32‐trnL(UAG) and trnH–psbA) markers, we reconstructed phylogenetic relationships within Onosma by conducting maximum parsimony, maximum likelihood, Bayesian, and BEAST analyses. The analyses revealed that Onosma as currently circumscribed is not monophyletic. However, the vast majority of Onosma species appear to belong to a single clade, the so‐called Onosma s.s. Outside of this core clade is a clade containing O. rostellata, a subclade of Sino‐Indian species and Maharanga emodii. Podonosma orientalis (as O. orientalis) appear only distantly related to Onosma but is more closely related to Alkanna, as also suggested in previous molecular studies. The Onosma s.s. clade includes all representatives of O. sect. Onosma, and encompasses three subsections, i.e. Onosma, Haplotricha and Heterotricha, corresponding to asterotrichous, haplotrichous and heterotrichous groups, respectively, but none of these subsections was retrieved as monophyletic. We observed significant incongruence between nuclear and chloroplast phylogenies regarding the phylogenetic status of the heterotrichous group. A dozen of the Iranian haplotrichous species formed a lineage which may not hybridize with asterotrichous species. Divergence time estimates suggested that the early radiation of Onosma s.l. took place at the Oligocene‐Miocene boundary and the diversification within Onosma s.s. occurred during middle to late Miocene and Pliocene.  相似文献   

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In this work 228 individuals of the whitemouth croaker Micropogonias furnieri collected in the Rocha coastal lagoon (Uruguay) from October 1997 to September 1998 were analysed. The species formed annuli in the otolith (sagitta) associated with the opaque zone (narrow opaque annulus), mainly in early winter when water temperature decreased, and reached the lowest values in July–August. The period of greatest growth occurred from December to June, partially overlapping with the spawning period (December–March) and in coincidence with the increase in marginal increment. Growth parameters determined for all individuals were K = 0.19, L = 30.2 and t0 = ?2.12. Annual growth increments showed that individuals grew rapidly and attained over 50% of their maximum observed size in the second year of life. In the third year, individuals attained sizes of first maturity at 11–12 cm less than estimates for the Río de la Plata spawning area and coastal areas of Brazil. The increment in length‐at‐age in the Rocha coastal lagoon was smaller than in individuals inhabiting the continental shelf (up to 50 m depth).  相似文献   

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Records of effects of ambient ozone pollution on vegetation have been compiled for Europe for the years 1990–2006. Sources include scientific papers, conference proceedings, reports to research funders, records of confirmed ozone injury symptoms and an international biomonitoring experiment coordinated by the ICP Vegetation. The latter involved ozone‐sensitive (NC‐S) and ozone‐resistant (NC‐R) biotypes of white clover (Trifolium repens L.) grown according to a common protocol and monitored for ozone injury and biomass differences in 17 European countries, from 1996 to 2006. Effects were separated into visible injury or growth/yield reduction. Of the 644 records of visible injury, 39% were for crops (27 species), 38.1% were for (semi‐) natural vegetation (95 species) and 22.9% were for shrubs (49 species). Owing to inconsistencies in reporting effort from year to year it was not possible to determine geographical or temporal trends in the data. Nevertheless, this study has shown effects in ambient air in 18 European countries from Sweden in the north to Greece in the south. These effects data were superimposed on AOT40 (accumulated ozone concentrations over 40 ppb) and POD3gen (modelled accumulated stomatal flux over a threshold of 3 nmol m?2 s?1) maps generated by the EMEP Eulerian model (50 km × 50 km grid) that were parameterized for a generic crop based on wheat and NC‐S/NC‐R white clover. Many effects were found in areas where the AOT40 (crops) was below the critical level of 3 ppm h. In contrast, the majority of effects were detected in grid squares where POD3gen (crops) were in the mid‐high range (>12 mmol m?2). Overall, maps based on POD3gen provided better fit to the effects data than those based on AOT40, with the POD3gen model for clover fitting the clover effects data better than that for a generic crop.  相似文献   

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