9 resultados para Radiolaria, Fossil

em Scielo Saúde Pública - SP


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A new species of sand fly, Pintomyia (Pifanomyia) falcaorum is described from an amber originated from the northern mountain range of Dominican Republic. The male sand fly specimen is well preserved and most features used in Phlebotominae taxonomy are seen with remarkable clarity.

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A discussion of the known fossil tabanids (Diptera Tabanidae) is presented based on fossil evidence. This includes the origin of the hemathophagy in the Brachycera, more specifically for tabanids. Several tabanid species in the extant fauna are vectors for disease-producing organisms that affect humans and animals. Bacteria, viruses, rickettsiae, protozoa, and filarial worms can be transmitted by them, causing such diseases as anthrax, tularemia, anaplasmosis, various forms of trypanosomiasis, Q fever, and filariasis. However, if tabanids are directly responsible for all of these diseases is not consensual and the known fossil evidence is presented here.

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Psychodid sand flies are blood-sucking fly vectors of several parasitic diseases. The oldest definitive record of this group is from the Lower Cretaceous amber of Lebanon (circa -135 to -125 My), but the high diversity within this group supports the idea that the psychodoids originated much earlier in history. The palaeontology demonstrates that the Lower Cretaceous representatives of the different subfamilies of Psychodidae had similar morphology and were blood-feeders, which supports Hennig's hypothesis on the ground plan structure of this family. Historical relationship between sand flies and diseases is unclear up to the present time, but this relationship could be as old as the origin of psychodoids because of the blood-feeding life mode.

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The fossil record and systematics of phlebotomid sand flies, vectors of leishmaniasis and arbovirus in several regions of the world, strongly support that living genera existed long before the Oligocene (38 million years, myr). A common Phlebotominae ancestor was present in the Triassic period before the separations of continents (248 myr).

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Molecular trees of trypanosomes have confirmed conventionally accepted genera, but often produce topologies that are incongruent with knowledge of the evolution, systematics, and biogeography of hosts and vectors. These distorted topologies result largely from incorrect assumptions about molecular clocks. A host-based phylogenetic tree could serve as a broad outline against which the reasonability of molecular phylogenies could be evaluated. The host-based tree of trypanosomes presented here supports the " invertebrate first " hypothesis of trypansosome evolution, supports the monophyly of Trypanosomatidae, and indicates the digenetic lifestyle arose three times. An area cladogram of Leishmania supports origination in the Palaearctic during the Palaeocene.

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A sand fly fossil was found in amber, a vegetal resin, which allows all the external phlebotomine structures to be seen. The piece that contains the new species is 14 mm long ´ 8 mm wide ´ 3 mm high. All the structures from the head, thorax, and abdomen were examined under the microscope and measured with a calibrated micrometric eye-piece. The morphological aspects of the new species suggest its inclusion in the Pintomyia genus, Pifanomyia subgenus though it is not possible to include it in any of the series known for this subgenus. The presence of two atrophied spines on the gonostyles and gonocoxites without tufts of setae permit the exclusion of the new species from the other species of the subgenus Pifanomyia. The new species is named Pintomyia (Pifanomyia) brazilorum sp. nov.

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Early Cretaceous flagellates with characters typical of trypanosomatids were found in the gut of sand fly larvae, as well as in surrounding debris, in Burmese amber. This discovery supports a hypothesis in which free-living trypanosomatids could have been acquired by sand fly larvae in their feeding environment and then carried transtadially into the adult stage. At some point in time, specific genera were introduced into vertebrates, thus establishing a dixenous life cycle.

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The description of Micropygomyia brandaoi, a new species of fossil phlebotomine sand fly, is based on one male specimen obtained from Dominican amber of the Miocene period (20 million years). In this new species, the fifth palpal segment is long, the coxite lacks a setal tuft and the style shows four well-developed spines. This set of characters allowed us to place the new species in the genus Micropygomyia Barretto.

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Biogeographic studies dealing with Bombyliidae are rare in the literature and no information is available on its origin and early diversification. In this study, we found evidence from molecular phylogeny and from fossil record supporting a Middle Jurassic origin of the Bombylioidea, taken as a starting point to discuss the biogeography and diversification of Crocidiinae. Based on a previously published phylogenetic hypothesis, we performed a Brooks Parsimony Analysis (BPA) to discuss the biogeographical history of Crocidiinae lineages. This subfamily is mostly distributed over arid areas of the early components of the Gondwanaland: Chile and southern Africa, but also in southwestern Palaearctic and southwestern Nearctic. The vicariant events affecting the Crocidiinae biogeography at the generic level seems to be related to the sequential separation of a Laurasian clade from a Gondwanan clade followed by the splitting of the latter into smaller components. This also leads to a hypothesis of origin of the Crocidiinae in the Middle Jurassic, the same period in which other bombyliid lineages are supposed to have arisen and irradiated.