Revisão taxonômica de Croton sect. Lamprocroton (Müll. Arg.) Pax (Euphorbiaceae s.s.)

Croton is the second bigger and more diverse genus in the family Euphorbiaceae, with about 1,200 species distributed in 40 sections, occurring in all tropical areas, most of them in Americas. In South America, Brazil is the country in which a larger number of taxa are found, ca. 356. According to recent classification, the genus belongs to the tribe Crotoneae, and despite the wide and morphological diversity, it would be a monophyletic taxon. However, a phylogenetic analysis using markers of ITS region from nuclear ribosomal DNA, and of trnL-F from plastidial DNA, showed that Croton, like traditionally circumscribed, is not a monophyletic taxon. A taxonomic revision of Croton section Lamprocroton (Müll. Arg.) Pax is presented here. It is a Neotropical group with most of its species occurring from Southeast and South Brazil to southern South America (Uruguay and Argentina). Morphologically, the members of Lamprocroton are characterized as monoecious or dioecious shrubs or subshrubs, with a lepidote indumentum at least in part of foliage, entire leaves with no glands. The staminate flowers have 9 to 16 stamens and the pistillate flowers may have equal or unequal sepals, reduced to absent petals, and styles once or twice bifid. Overall, are recognized 26 species in the group, three of them new to the science. Identification key, morphological descriptions, illustrations, phenological period, as well as data on geographic distribution and general comments of each species are presented. Four taxa were excluded from C. sect. Lamprocroton because they do not show the morphological features that are diagnostics of the section. Four species that are poorly known were not included in the taxonomic treatment.

Oligosarcus jacuiensis (Characiformes: Characidae), a new species from the Uruguay and Jacuí River basins, southern Brazil

The new species herein described, collected in the Jacuí and Uruguay River basins, Rio Grande do Sul, Brazil, can be distinguished from the already known species of the genus, but Oligosarcus jenynsii, O. perdido, O. acutirostris, O. solitarius and O. hepsetus, by the number of perforated lateral line scales. It shares with the first two species the absence of a premaxillary foramen, present in the last three species and differs from O. jenynsii by having a smaller orbital diameter and the tip of the pectoral fin failing to reach the pelvic-fin origin, and from O. perdido by the presence of more horizontal scale rows around the caudal peduncle.

Serological evidence of Rickettsia parkeri as the etiological agent of rickettsiosis in Uruguay

We report three new rickettsiosis human cases in Uruguay. The three clinical cases presented clinical manifestations similar to previous reported cases of Rickettsia parkeri in the United States; that is mild fever (< 40 ºC), malaise, headache, rash, inoculation eschar at the tick bite site, regional lymphadenopathy, and no lethality. Serological antibody-absorption tests with purified antigens of R. parkeri and Rickettsia rickettsii, associated with immunofluorescence assay indicated that the patients in two cases were infected by R. parkeri. Epidemiological and clinical evidences, coupled with our serological analysis, suggest that R. parkeri is the etiological agent of human cases of spotted fever in Uruguay, a disease that has been recognized in that country as cutaneous-ganglionar rickettsiosis.

Major shear zones of southern Brazil and Uruguay: escape tectonics in the eastern border of Rio de La plata and Paranapanema cratons during the Western Gondwana amalgamation

The Mantiqueira Province represents a series of supracrustal segments of the South-American counterpart formed during the Gondwana Supercontinent agglutination. In this crustal domain, the process of escape tectonics played a conspicuous role, generating important NE-N-S-trending lineaments. The oblique component of the motions of the colliding tectonic blocks defined the transpressional character of the main suture zones: Lancinha-Itariri, Cubato-Arcadia-Areal, Serrinha-Rio Palmital in the Ribeira Belt and Sierra Ballena-Major Gercino in the Dom Feliciano Belt. The process as a whole lasted for ca. 60 Ma, since the initial collision phase until the lateral escape phase predominantly marked by dextral and subordinate sinistral transpressional shear zones. In the Dom Feliciano Belt, southern Brazil and Uruguay, transpressional event at 630-600 Ma is recognized and in the Ribeira Belt, despite less coevally, the transpressional event occurred between 590 and 560 Ma in its northern-central portion and between ca. 625 and 595 Ma in its central-southern portion. The kinematics of several shear zones with simultaneous movement in opposite directions at their terminations is explained by the sinuosity of these lineaments in relation to a predominantly continuous westward compression.

Petrogenesis of Early Cretaceous silicic volcanism in SE Uruguay: The role of mantle and crustal sources

Early Cretaceous (similar to 129 Ma) silicic rocks crop out in SE Uruguay between the Laguna Merin and Santa Lucia basins in the Lascano, Sierra Sao Miguel. Salamanca and Minas areas They are mostly rhyolites with minor quartz-trachytes and are nearly contemporaneous with the Parana-Etendeka igneous province and with the first stages of South Atlantic Ocean opening A strong geochemical variability (particularly evident from Rb/Nb, Nb/Y trace element ratios) and a wide range of Sr-Nd isotopic ratios ((143)Nd/(144)Nd((129)) = 0.51178-0.51209, (87)Sr/(86)Sr((129)) = 0.70840-0.72417) characterize these rocks Geochemistry allows to distiniguish two compositional groups, corresponding to the north-eastern (Lascano and Sierra Sao Miguel, emplaced on the Neo-Proterozoic southern sector of the Dom Feliciano mobile belt) and south-eastern localities (Salamanca, Minas, emplace on the much older (Archean) Nico Perez teriane or on the boundary between the Dom Feliciano and Nico Perez termites) These compositional differences between the two groups are explained by variable mantle source and crust contributions. The origin of the silicic magmas is best explained by complex processes involving assimilation and fractional crystallization and mixing of a basaltic magma with upper crustal lithologies, for Lascano and Sierra Sao Miguel rhyolites. In the Salamanea and Minas rocks genesis, a stronger contribution from lower crust is indicated.

The basement of the Punta del Este Terrane (Uruguay): an African Mesoproterozoic fragment at the eastern border of the South American Rio de La Plata craton

The Punta del Este Terrane (eastern Uruguay) lies in a complex Neoproterozoic (Brasiliano/Pan-African) orogenic zone considered to contain a suture between South American terranes to the west of Major Gercino-Sierra Ballena Suture Zone and eastern African affinities terranes. Zircon cores from Punta del Este Terrane basement orthogneisses have U-Pb ages of ca. 1,000 Ma, which indicate an lineage with the Namaqua Belt in Southwestern Africa. U-Pb zircon ages also provide the following information on the Punta del Este terrane: the orthogneisses containing the ca. 1,000 Ma inheritance formed at ca. 750 Ma; in contrast to the related terranes now in Africa, reworking of the Punta del Este Terrane during Brasiliano/Pan-African orogenesis was very intense, reaching granulite facies at ca. 640 Ma. The termination of the Brasiliano/Pan-African orogeny is marked by formation of acid volcanic and volcanoclastic rocks at ca. 570 Ma (Sierra de Aguirre Formation), formation of late sedimentary basins (San Carlos Formation) and then intrusion at ca. 535 Ma of post-tectonic granitoids (Santa Teresa and Jos, Ignacio batholiths). The Punta del Este Terrane and unrelated western terranes represented by the Dom Feliciano Belt and the Rio de La Plata Craton were in their present positions by ca. 535 Ma.

Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) resistance to fipronil in Uruguay evaluated by in vitro bioassays

Rhipicephalus (Boophilus) microplus obtained from four local populations in Uruguay (2007-2008) were subjected to various bioassay techniques to determine the presence of fipronil resistance within the country. Resistance ratios (RRs) obtained by larval immersion test varied between 3.3 and 3635 for tick populations subjected to treatment with fipronil for the last 3-7 years. The highest RR was observed in the population which received fewer treatments. Using discriminating concentration (8 ppm) for larval immersion test, all field strains were correctly diagnosed as fipronil-resistant. This study presents the first diagnoses of cattle tick resistance to fipronil in Uruguay`s field populations. It also highlights the importance of the possible conflict between programs to control agricultural pests and cattle ticks. The findings provide valuable information for selection and adoption of new control alternatives to manage drug resistance exhibited by cattle ticks. (C) 2009 Elsevier BM. All rights reserved.

Determination of the susceptibility of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) to ivermectin and fipronil by Larval Immersion Test (LIT) in Uruguay

Rhipicephalus (Boophilus) microplus is an important cattle pest in Uruguay, and the law regulates its control. It is resistant to organophosphates, synthetic pyrethroids and, as recently discovered, to fipronil. Resistance to macrocyclic lactones (MLs) and amitraz have not been documented; however, veterinarians and farmers have reported treatment failures. The objective of the present work was to study the susceptibility of cattle tick strains from different Uruguayan counties to ivermectin (IVM) and fipronil by using the Larval Immersion Test (LIT). The Mozo strain was used as the susceptible reference strain. From 2007 to 2009, twenty-eight tick populations were collected from different cattle farms with and without history of IVM or fipronil use. A probit analysis estimated dose-mortality regressions, lethal concentrations (LC), and confidence intervals. The resistance ratio (RR) was determined at the LC(50) and LC(90) estimates. To classify a tick population in relation to resistance, three categories based on a statistical analysis of LC and RR between field populations and Mozo strains were defined: susceptible (no differences), incipient resistance (differences and RR(50) < 2) and resistant (differences and RR(50) >= 2). Eighteen field populations were tested with IVM and five of them presented a RR(50) range between 1.35 and 1.98 and the LC(50/90), which is statistically different from the Mozo strain (incipient resistance). However, the RR(90) increases >= 2 in four of the populations, confirming that tick resistance to IVM is emergent. The low RR values obtained could be a result of a low frequency of treatments with IVM. Twenty-seven tick populations were tested with fipronil and six were diagnosed as resistant according to the LIT. Cross-resistance was not observed between fipronil and IVM on these tick populations. The current study presents different R. (B.) microplus populations with an incipient resistance to IVM, and indicates that the fipronil tick resistance is restricted to certain areas in Uruguay. (c) 2011 Elsevier B.V. All rights reserved.