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American Taxa (american + taxa)
Selected AbstractsA new platysomid from the Upper Carboniferous of Kansas (USA) and remarks on the systematics of deep-bodied lower actinopterygiansACTA ZOOLOGICA, Issue 2009Kathryn E. Mickle Abstract Scales and presumptive tooth plates from deep-bodied platysomid actinopterygians have previously been reported from the Lower Permian of Kansas (USA), but until now, an articulated specimen from this state has not been recovered. The first articulated deep-bodied platysomid fish from the Upper Carboniferous of Kansas is described herein. This specimen is compared to other known species from the genus Platysomus, with special attention paid to the North American taxa. The cranial osteology of this new specimen is closest to Platysomus schultzei from the Upper Carboniferous of New Mexico. The newly described platysomid species highlights the need for a revision of the fish included within the genus Platysomus. [source] Relationships in Taraxacum section Arctica s.l. (Asteraceae, Cichorieae) and allies based on nrITSFEDDES REPERTORIUM, Issue 1-2 2009I. Uhlemann nrITS sequences of 19 Taraxacum -species as well as four outgroups of Asteraceae-Cichorieae were analysed using Bayesian and parsimony analyses in order to establish their systematics. The Arctica s.l. clade together with T. bessarabicum is sister to all derived European and South American taxa. The division of Arctica s.l. into smaller units (sections: Antarctica, Arctica s. str., Australasica) is supported. Within the remaining taxa, Taraxacum farellonicum, a species from the Chilean Andes which is described as new, is supposed to be a hybrid of T. gilliesii and an introduced Ruderalia -species. Section Erythrosperma is well separated and supported. With the exception of T. patagonicum and T. bracteatum which are sister to the other representatives of the European taxa two groups are distinguished: first the Ruderalia/Hamata alliance (including T. tenebricans with some exceptional characters) of predominantly ruderal species and second an assemblage of the sections Celtica, Fontana, Macrodonta, Palustria and Taraxacum prefering a lesser ruderal habitate. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Molekulare Systematik der Gattung Taraxacum Sektion Arctica s.l. (Asteraceae, Cichorieae) und verwandter Arten auf der Basis von nuklearer ribosomaler DNA (nrITS) Die Verwandtschaftsverhältnisse von 19 Arten der Gattung Taraxacum und vier Außengruppen aus den Asteraceae-Cichorieae wurden mit Bayesischen und Parsimonieanalysen der nrITS Sequenzen rekonstruiert. Die Sektion Arctica s.l. bildet zusammen mit T. bessarabicum die Schwestergruppe zu den abgeleiteten europäischen und südamerikanischen Taxa. Die Klassifizierung der Arctica s.l. in die Sektionen Antarctica, Arctica s.str. und Australasica wird von den Analysen unterstützt. Die in dieser Studie neu beschriebene Art, Taraxacum farellonicum, aus den chilenischen Anden ist wahrscheinlich ein Hybrid aus T. gilliesii und einer neophytischen Art der Sektion Ruderalia. Die Sektion Erythrosperma erscheint als gut gestützte Gruppe. Mit Ausnahme von T. patagonicum und T. bracteatum, die Schwestergruppen zu den anderen Vertretern europäischer Taxa bilden, können zwei größere Komplexe unterschieden werden: erstens die Ruderalia/Hamata -Gruppe (einschließlich T. tenebricans mit einigen besonderen Merkmalen), welche vorwiegend Arten der ruderalen Standorte umfasst und zweitens ein Verwandtschaftskreis aus den Sektionen Celtica, Fontana, Macrodonta, Palustria und Taraxacum, die an weniger stark ruderalisierten Standorten vorkommen. [source] Phylogeny and biogeography of Yellow-headed and Blue-fronted Parrots (Amazona ochrocephala and Amazona aestiva) with special reference to the South American taxaIBIS, Issue 3 2007CAMILA C. RIBAS The Yellow-headed Parrot (Amazona ochrocephala) has a broad Neotropical distribution, ranging from Mexico to the Amazon Basin, and a history of complex taxonomy and controversial species limits. Recent molecular analyses have started to clarify the taxonomic arrangement of the complex, but have not included a representative geographical sampling from South America. These studies have shown that the Yellow-headed complex can be divided into three main lineages, and seems to be paraphyletic, due to the inclusion of the Blue-fronted Parrot (Amazona aestiva) that occurs in central South America. Here we present a phylogenetic analysis based on mitochondrial DNA sequences of 45 representatives of the Yellow-headed complex from South and Central America, plus 13 Blue-fronted individuals from different localities in South America. Our analyses recover the three primary lineages found previously in the Yellow-headed complex, show that there is genetic structure in the South American lineage, which can be divided into two well-supported, closely related clades, and demonstrate that Blue-fronted samples are distributed in both clades. Differentiation of South American Blue-fronted and Yellow-headed Parrot populations does not correspond to the plumage differences used to distinguish the Blue-fronted Parrot from the Yellow-headed Parrot, nor to plumage differences used to distinguish among South American Yellow-headed subspecies. This suggests that traditional taxonomy based on plumage characters needs revision, and that this may be an interesting example of ongoing divergence-with-gene-flow related to the forest/open area ecotone in southern Amazonia. [source] The biogeography of Gunnera L.: vicariance and dispersalJOURNAL OF BIOGEOGRAPHY, Issue 7 2003Livia Wanntorp Abstract Aim The genus Gunnera is distributed in South America, Africa and the Australasian region, a few species reaching Hawaii and southern Mexico in the North. A cladogram was used to (1) discuss the biogeography of Gunnera and (2) subsequently compare this biogeographical pattern with the geological history of continents and the patterns reported for other Southern Hemisphere organisms. Location Africa, northern South America, southern South America, Tasmania, New Zealand, New Guinea/Malaya, Hawaii, North America, Antarctica. Methods A phylogenetic analysis of twenty-six species of Gunnera combining morphological characters and new as well as published sequences of the ITS region, rbcL and the rps16 intron, was used to interpret the biogeographical patterns in Gunnera. Vicariance was applied in the first place and dispersal was only assumed as a second best explanation. Results The Uruguayan/Brazilian Gunnera herteri Osten (subgenus Ostenigunnera Mattfeld) is sister to the rest of the genus, followed sequentially upwards by the African G. perpensa L. (subgenus Gunnera), in turn sister to all other, American and Australasian, species. These are divided into two clades, one containing American/Hawaiian species, the other containing all Australasian species. Within the Australasian clade, G. macrophylla Blume (subgenus Pseudogunnera Schindler), occurring in New Guinea and Malaya, is sister to a clade including the species from New Zealand and Tasmania (subgenus Milligania Schindler). The southern South American subgenus Misandra Schindler is sister to a clade containing the remaining American, as well as the Hawaiian species (subgenus Panke Schindler). Within subgenus Panke, G. mexicana Brandegee, the only North American species in the genus, is sister to a clade wherein the Hawaiian species are basal to all south and central American taxa. Main conclusions According to the cladogram, South America appears in two places, suggesting an historical explanation for northern South America to be separate from southern South America. Following a well-known biogeographical pattern of vicariance, Africa is the sister area to the combined southern South America/Australasian clade. Within the Australasian clade, New Zealand is more closely related to New Guinea/Malaya than to southern South America, a pattern found in other plant cladograms, contradictory to some of the patterns supported by animal clades and by the geological hypothesis, respectively. The position of the Tasmanian G. cordifolia, nested within the New Zealand clade indicates dispersal of this species to Tasmania. The position of G. mexicana, the only North American species, as sister to the remaining species of subgenus Panke together with the subsequent sister relation between Hawaii and southern South America, may reflect a North American origin of Panke and a recolonization of South America from the north. This is in agreement with the early North American fossil record of Gunnera and the apparent young age of the South American clade. [source] The flora of the South Sandwich Islands, with particular reference to the influence of geothermal heatingJOURNAL OF BIOGEOGRAPHY, Issue 6 2000P. Convey Abstract Aim, To carry out as comprehensive a survey as practicable of the flora (higher plants, mosses, liverworts, lichens, basidiomycete fungi and diatoms) of the isolated, volcanically active, South Sandwich Islands archipelago in the southern South Atlantic. To relate the components of this flora to (1) the influence of local geothermal heating and (2) wider regional floras. Location, South Sandwich Islands, southern South Atlantic Ocean, maritime Antarctic (56,60° S, 26,28° W). Methods, Ice-free accessible sites on all 11 of the major islands in the archipelago were visited by helicopter in January 1997. During each visit, voucher specimens of each floral group were collected. The comprehensiveness of collections obtained at each site varied with the duration of each visit (a function of tight logistic constraints) and extent of site. Visit duration varied from 1 to 9 h at most sites, with longer periods spent on Bellingshausen Island (2 days) and Leskov Island (1 day). Candlemas Island was examined in greater detail over a 4-week period in February 1997. At all sites, particular attention was given to areas influenced by geothermal heating. Results, Data obtained in 1997 are combined with updated records from the only previous survey (in 1964) to provide a baseline description of the flora of the archipelago, which currently includes 1 phanerogam, 38 mosses, 11 liverworts, 5 basidiomycete fungi, 41 lichenised fungi and 16 diatoms with, additionally, several taxa identified only to genus. Major elements of the moss and liverwort floras are composed of South American taxa (32% and 73%, respectively), with a further 45% of mosses having bipolar or cosmopolitan distributions. These two groups show low levels of Antarctic endemicity (11% and 18%, respectively). In contrast, 52% of lichens and 80% of basidiomycete fungi are endemic to the Antarctic. A further 36% of lichens are bipolar/cosmopolitan, with only 5% of South American origin. Main Conclusions, The flora of the South Sandwich Islands is clearly derived from those of other Antarctic zones. The flora of unheated ground is closely related to that of the maritime Antarctic, although with a very limited number of species represented. That of heated ground contains both maritime and sub-Antarctic elements, confirming the importance of geothermal heating for successful colonisation of the latter group. The occurrence of several maritime Antarctic species only on heated ground confirms the extreme severity of the archipelago's climate in comparison with well-studied sites much further south in this biogeographical zone. [source] | ||||||||||