Ostracods and paleoambiental inferences in the Plottier Formation (Coniancian - Upper Cretaceous) of the Barreales Lake, Neuquén

Upper Cretaceous outcrops, at the northeast of Barreales lake, Neuquén, Argentina, has given in the last 20 years a rich vertebrate fauna including dinosaur, reptiles, fish and plants on different sites. In this contribution, rocks of the Plottier Formation at Babilonia Site at Proyecto Dino Geopaleontological Park have given, for the first time, an interesting microfauna composed by ostracods. The ostracofauna recovered is represented by the family Ilyocyprididae with four taxa, Neuquenocypris calfucurensis Musacchio, 1973, Neocyprideis zampalensis (Angelozzi, 1980), Neuquenocypris tenuipunctata Musacchio & Simeoni, 1991 and Neuquenocypris nahuelniyuensis Musacchio, 1989 and the family limnocytheridae, with one taxa Vecticypris sp. The ssociation of theses ostracod indicates a paleoenvironment characterized by a shallow meandering river with low energy, probably an abandoned oxbow lake. Palaeoecological analyses indicate a fresh water with fluctuating oligohaline salinities throughout deposition.Fil: Kihn, Romina Gisela. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Calvo, Jorge Orlando. Universidad Nacional del Comahue. Centro Paleontológico Lago Barreales; Argentin

Ostracods of shallow lakes of the central region of Argentina: Paleolimnological implications

Studies about ostracods in shallow lakes are very scarce in the Province of La Pampa, thus the objective of this work is to contribute to the knowledge of the species present in lentic environments, studying the distribution, abundance, and specific associations of ostracods. The samples come from four shallow lakes of the Pampean Region, Province of La Pampa, Argentina. Sampling was performed along transects perpendicular to the shore. Five genera represented by six species of benthic ostracods were identified. Heterocypris similis was present in all sampled water bodies, but was dominant in the Monte de Caldén (LCM) and Don Tomás (LDT) lagoons. Cypridopsis vidua was very abundant in the LCM. The species Chlamydotheca incisa and Potamocypris unicaudata were only recorded in the Ojo de Agua Lagoon (LCS). C. incisa is recorded for the first time in the province, and P. unicaudata in Argentina. The qualitative and quantitative variations of the ostracod assemblages can be related to topography, sedimentology, vegetation and salinity variations. The results of this study are important in the interpretation of the environments recorded during the Quaternary, since these species are also registered as fossils.Estudos sobre ostracodes em lagoas pouco profundas são muito escassos na Província de La Pampa, Argentina, e, portanto, o objetivo deste trabalho é contribuir para o conhecimento das espécies presentes nos ambientes lenticais, estudar distribuição, abundância e associações específicas de ostracodes. As amostras provêm de quatro lagoas da Região Pampeana, Província de La Pampa, Argentina. Amostragem sazonal foi realizada ao longo de um corte transversal perpendicular à costa, tendo sido identificado um total de cinco gêneros representados por seis espécies de ostracodes bentônicos. Heterocypris similis está presente em todos os corpos de água amostrados, mas é dominante nas lagunas Monte de Caldén (LCM) e Don Tomás (LDT). Cypridopsis vidua é muito abundante na LCM. As espécies Chlamydotheca incisa e Potamocypris unicaudata somente foram registradas na Laguna Ojo de Agua (LCS). C. incisa é o primeiro registro para a província e P. unicaudata é a primeira nomeação para a Argentina. As variações qualitativas e quantitativas dos conjuntos ostracodes podem estar relacionadas à topografia, sedimentologia, vegetação e variações de salinidade. Os resultados deste estudo são importantes na interpretação dos ambientes registrados durante o Quaternário, uma vez que estas espécies também ocorrem como fósseis.Fil: Kihn, Romina Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Crespo, Florencia. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Pall, José Luis María. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentin

Calcareous and siliceous microorganisms of the “Don Tomás” Lagoon, La Pampa Province, Argentina

Studies on diatoms, cysts and ostracods in shallow lakes are very scarce in the Province of La Pampa. The aim of this study is to collect new information on the diversity and abundance of microorganisms present in a hypertrophic body of water and their seasonal changes. The samplings were carried out seasonally in the period from January to October 2014. From the sediment analysis of the Don Tomás lagoon, 21 diatom taxa were identified, of which three correspond to the order Centrales and 18 to the order Pennales; four genera of ostracods and two morphotypes of chrysophyte cysts (ornamented and smooth) were also recorded. The data obtained from the study of current samples will allow us to interpret with a greater degree of certainty the Holocene deposits from lake environments of temperate climates.Estudos sobre diatomáceas, cistos e ostracodes em lagos rasos são muito escassos na Província de La Pampa, portanto, o objetivo deste estudo foi coletar informações sobre a diversidade e abundância dos microrganismos presentes em um corpo d’água hipertrófico e suas mudanças sazonais. As coletas foram realizadas sazonalmente no período de janeiro a outubro de 2014. A partir da análise de sedimentos da lagoa "Don Tomás", foram identificados 21 táxons de diatomáceas, dos quais três correspondem à ordem Centrales e 18 à ordem Pennales; quatro gêneros de ostracodes e dois morfotipos de cistos de Crysophyta (ornamentados e lisos) também foram registrados. Os dados obtidos no estudo das amostras atuais permitirão a interpretação dos depósitos holocênicos de ambientes lacustres em climas temperados com maior grau de confiabilidade.Fil: Kihn, Romina Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Gutierrez Tellez, Beatriz Monica. Universidad Nacional del Sur. Departamento de Geología; Argentin

Biodiversity of the ants (insecta: hymenoptera) associated with the center agroecosystems of Argentina

The world change in land use and crop modification has been, at the expenses of forests, pastures and swamps. Argentina pampean plains have not been an exception because of this global tendency with an agricultural border continuous advance from the east to the semiarid west. This generates a loss of biological diversity that affects a great number of organisms among which we find the ants, which play a very important role in the communities structure doing a balance between living creatures and their habitat. The aim of this work is compare the myrmecofauna associated with productive agroecosystems in the central region of Argentina, through the evaluation richness of these insects and diversity. The hypothesis of this study is to test the diversity of Formicidae in fields where little anthropogenic is greater than in agroecosystems of central Argentina. Three farms were chosen as study sites, each of them divided into two sampling sites that correspond to cultivated or natural areas. A total of 5.647 ants were collected among which three dominant species were found in all the sites: Dorymyrmex breviscapis, Solenopsis saevissima and Pheidole bergi. Significant differences were observed between the agroecosystems myrmecofauna and the natural environments.Fil: Pall, José Luis María. Universidad Nacional de la Pampa. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Naturales. Pabellon de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kihn, Romina Gisela. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bernardos, Jaime. Instituto Nacional de Tecnología Agropecuaria. Centro Regional la Pampa-san Luis. Estación Experimental Agropecuaria Anguil; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Quirán, Estela Maris. Universidad Nacional de la Pampa. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Naturales. Pabellon de Biología; Argentin

A review of genus Nysius Dallas in Argentina (Hemiptera: Heteroptera: Orsillidae)

The orsillid genus Nysius Dallas is a complex and large genus with more than 100 described species worldwide, and includes many species of agricultural importance, one such example is N. simulans (Stål) from Argentina. Three species of Nysius are found in this country: N. simulans (Stål), N. irroratus (Spinola) and N. puberulus Berg. The material available for the present study, consisting of over 610 specimens, was collected by sweep-net, G-Vac and light trap in the provinces of Chubut (42° to 46°S; 63.5° to 72° W), La Pampa (35º to 39º south; 63º to 68º West), Neuquén (36° to 41° S; 68° to 71°W) and Río Negro (37° to 42°S; 62° to 71°W), in the central region of Argentina, during the years 2010–2014. Although the species N. simulans is frequently recorded as a pest of soybean crop, there exist no detailed description but only a brief general diagnosis. In the present contribution, therefore, we provide a detailed redescription as well as an updated distribution of N. simulans and N. irroratus, and a key for species of genus Nysius present in Argentina.Facultad de Ciencias Naturales y Muse

Associations of ostracods in shallow lakes in the northeast of La Pampa province (Argentina)

Los lagos someros son frecuentes en La Pampa. Aunque muchas características de su biota son conocidas, la información sobre la distribución y ecología de los ostrácodos es escasa, a pesar de su importancia como indicadores biológicos y en actuopaleontología. El objetivo de este estudio es conocer la composición taxonómica, la densidad de ostrácodos y sus relaciones con parámetros ambientales en lagos del noreste de La Pampa. Se estudiaron cinco lagos desde septiembre de 2016 hasta marzo de 2017. Se tomaron muestras de sedimentos superficiales e in situ se midieron: conductividad, temperatura y transparencia y se tomaron muestras para determinar salinidad, pH y composición iónica. Los lagos difirieron en su salinidad, composición iónica y transparencia. Se registraron diez taxa, algunos hallados previamente en la provincia de Buenos Aires (Heterocypris similis, Heterocypris incongruens, Cypridopsis vidua y Chlamydotheca incisa), la cuenca de Llancanelo (H. incongruens y C. vidua) y lagos del norte de Patagonia (C. incisa, C. vidua, Potamocypris unicaudata, H. incongruens y Amphicypris argentiniensis). Se comprobó la influencia de la salinidad ya que algunas especies (A. argentinensis, Limnocythere rionegroensis y Limnocythere titicaca) se encontraron sólo en el lago más salino. La existencia en La Pampa de tres ecorregiones diferentes (Llanura Pampeana, Espinal y Estepa Patagónica) y la presencia en los lagos estudiados de ostrácodos del noroeste argentino (L. titicaca), de la llanura bonaerense (H. similis, H. incongruens) y otras de Patagonia (L. rionegroensis), permitiría afirmar que los lagos de La Pampa están en una zona de transición entre faunas diferentes.Shallow lakes are common in the center of Argentina. Although many characteristics of its biota are known, information on the distribution and ecology of ostracods is scarce despite their importance as biological indicators and in actuopaleontology. The objective of this study was to determine the taxonomic composition, the density of ostracods, and their relationships with environmental parameters in lakes in the northeast of La Pampa. Five aquatic ecosystems were studied from September 2016 to March 2017. Samples of superficial sediments were collected, and conductivity, temperature, and transparency were measured in situ. Water samples were collected to determine salinity, pH, and ionic composition. The lakes differed in salinity, ionic composition, and transparency. Ten taxa were registered, some previously found in the province of Buenos Aires (Heterocypris similis, Heterocypris incongruens, Cypridopsis vidua, and Chlamydotheca incisa), the Llancanelo basin (H. incongruens and C. vidua), and North Patagonia lakes (C. incisa, C. vidua, Potamocypris unicaudata, H. incongruens, and Amphicypris argentiniensis). The influence of salinity was verified because some species (A. argentinensis, Limnocythere rionegroensis, and Limnocythere titicaca) were found only in the most saline lake. The existence in La Pampa of three different ecoregions (Pampean Plains, Espinal, and Patagonian Steppe) and the presence of ostracods in the studied lakes of northwestern Argentina (L. titicaca), the Buenos Aires province plain (H. similis, H. incongruens), and Patagonia (L. rionegroensis) allowed for affirming that the lakes of La Pampa are in a transition zone among different ostracods faunas.Fil: Kihn, Romina Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Echaniz, Santiago Andrés. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Vignatti, Alicia María. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Cabrera, Gabriela Cecilia. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Stella, Cesar A.. Museo Provincial de Ciencias Naturales; Argentin

Recent and Holocene Benthic Ostracod assemblages of the Bahia Blanca estuary: (Buenos Aires, Argentina): Palaeoenvironmental Interpretations

The study of ostracod fauna in sediment samples from present environments at the Bahía Blanca estuary led to the identification of different ostracod associations, through which it was possible to identify Holocene depositional environments. Based on the systematic analysis of the ostracods present in different core levels, a total of 11 genera represented by 13 species of benthic ostracods were identified, out of which Neocytherideis ruidis, Loxocythere variasculpta and Callistocythere litoralensis were dominant along the core. The quantitative and qualitative analysis of ostracods from the Holocene allowed us to determine the following palaeoenvironments: at the base of the core the sediments were deposited in an intertidal environment with developed mudflats; the middle sector evidenced an increase in environmental energy; and the upper portion of the core contained deposits of marshes environment with greater freshwater input. The detailed study of the benthic Ostracoda allowed to identify palaeoenvironments and to provide new evidence of negative fluctuations of the mean sea level for the Holocene.O estudo da fauna presente nas amostras de sedimento de ambientes atuais do Estuário de Bahía Blanca permitiu a identificação de diferentes associações de ostracodes que facilitaram o reconhecimento dos ambientes deposicionais do Holoceno. A partir da análise sistemática da ostracofauna encontrada nos diferentes níveis do testemunho, foi identificado um total de 11 gêneros representados por 13 espécies de ostracodes bentônicos, entre as quais houve um predomínio de Neocytherideis ruidis, Loxocythere vasriasculpta e Callistocythere litoralensis ao longo de todo o testemunho. A análise quantitativa e qualitativa da ostracofauna do Holoceno permitiu determinar os seguintes paleoambientes: na base do testemunho os sedimentos foram depositados em uma zona entremarés com marismas desenvolvidas; na parte média observou-se um aumento na energia ambiental e no topo do testemunho foram registrados depósitos de um ambiente de marismas com maior presença de águas continentais. O estudo detalhado dos ostracodes bentônicos permitiu identificar paleoambientes e fornecer novas evidências de flutuações negativas do nível médio do mar para o Holoceno.Fil: Kihn, Romina Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Martínez, Dina Elsa. Universidad Nacional del Sur. Departamento de Geología; ArgentinaFil: Gomez, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Borel, Claudia Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentin

Diversity of zooplankton in aquatic ecosystems of the northeast of La Pampa (Argentina) with emphasis on new species registered for the province

En la región noreste de la provincia de La Pampa existe una gran cantidad de ecosistemas acuáticos muy heterogéneos, sin embargo los estudios limnológicos sobre ellos son escasos. El objetivo es describir la composición del zooplancton de cinco cuerpos de agua y reportar la presencia de seis especies no registradas en la provincia. Entre 2016 y 2017 se tomaron muestras en dos pequeños lagos (“ojos de agua”) subsalinos, de alta transparencia, con vegetación arraigada y en tres lagunas sub o hiposalinas, sin vegetación y menor transparencia. Se registraron ocho cladóceros, nueve copépodos y 27 rotíferos. En todos los casos los rotíferos dominaron en número de especies y densidad pero las comunidades zooplanctónicas de los ojos de agua fueron diferentes de las de las lagunas. Los ambientes estudiados están en un área geográfica reducida, pero su diversidad fue mayor que la encontrada en áreas más extensas de La Pampa, lo que puede deberse a la heterogeneidad de los ecosistemas acuáticos incluidos en este estudio. Tres copépodos (Argyrodiaptomus bergi, Boeckella bergi y Eucyclops neumani) y tres rotíferos (Euchlanis dilatata, Lecane closterocerca y Plationus patulus) son citados por primera vez para la provincia de La Pampa. Este estudio confirma que la distribución de A. bergi y E. neumani es más amplia que la conocida hasta ahora, restringida a Brasil y la cuenca del Paraná - del Plata, pero el resto son especies extensamente distribuidas en Argentina. En consecuencia, la falta de información en La Pampa se debió a la ausencia de investigaciones previas.The northeastern region of La Pampa province has a large number of heterogenic aquatic ecosystems; however, limnological studies of these ecosystems are scarce. The objective of this study is to describe the composition of the zooplankton of five water bodies and report the presence of six species not previously registered in the province. Between 2016 and 2017, samples were taken in two small, highly transparent subsaline lakes (“water holes”) with rooted vegetation and in three sub- or hyposaline shallow lakes, without vegetation and with less transparency. Eight cladocerans, nine copepods, and 27 rotifers were recorded. In all cases, rotifers dominated in number of species and density, but the zooplankton communities of the water holes differed from those of the shallow lakes. The aquatic ecosystems studied are in a reduced geographic area, but their diversity was greater than that of larger areas of La Pampa, which may be due to the heterogeneity of the water bodies included in this study. Three copepods (Argyrodiaptomus bergi, Boeckella bergi, and Eucyclops neumani) and three rotifers (Euchlanis dilatata, Lecane closterocerca, and Plationus patulus) have been identified for the first time in La Pampa province. This study confirms that the distribution of A. bergi and E. neumani is wider than known so far, which was restricted to Brazil and the Paraná - del Plata basin, but the remaining zooplankton are species widely distributed in Argentina. Thus, the lack of information in La Pampa was due to the absence of previous investigations.Fil: Echaniz, Santiago Andrés. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Vignatti, Alicia María. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Cabrera, Gabriela Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Kihn, Romina Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Stella, Cesar A.. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentin

Invasion of Cyprideis salebrosa (Ostracods, Crustaceans) in Bahia Blanca Estuary, Buenos Aires, Argentina

Large populations of the living benthic ostracoda Cyprideis salebrosa Van den Bold, 1963 are reported for the first time from marsh and intertidal mud flat sediments of the Bahía Blanca estuary (Argentina). C. salebrosa has been found in current sediments of the inner zone of the estuary of Bahia Blanca in lower densities than 15%. The highest abundance values were recorded in the Villarino Viejo place (VV1-VV4) where 200 individuals of C. salebrosa were found in 6 g of dry-sediment, and the B4 samples from the Club Almirante Brown. At this site C. salebrosa represents from 96 to 100% of all benthic ostracoda. Towards the mouth and the outer zone of the estuary (site V and VV) C. salebrosa represents approximately from 70 of 100% of the total ostracoda assemblage. The prolific distribution of C. salebrosa the levels of eutrophication in the Bahía Blanca estuary is very important in some places and directly affecting the diversity of ostracod assemblages present; It is C. salebrosa the only species present on the sites with the highest degree of eutrophication. If these conditions continue throughout the benthic community will be affected.Fil: Kihn, Romina Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentin

Predation on recent Marine and Fresh-Water Ostracod populations of The Central Region of The Republic Argentina

The presence of evidence of depredation in ostracods valves from marine and freshwater environments of the central region of the republic Argentina are studied in this paper. In samples from intertidal environment (Puerto Rosales) a total of 800 shells of ostracods were recovered of which only 0.50% (4 valves) presented evidence of predation. In freshwater environments (Laguna Don Tomás) a total of 1447 valves were recovered of which only 1.10% (16 valves) presented evidence of predation. Two types of depredation fossil traces were determined: Oichnus simplex Bromley and Oichnus paraboloides Bromley. Oichnus simplex Bromley predominate over drilling Oichnus paraboloids Bromley attributed to predatory gastropods activity, both marine and continental environments. There was not relationship between the borehole diameter and the size of the predated valves. The ornamentation of the valves is not a character that conditions predation, since the species predated have different type of ornamentation from thin ribs to crosslinks with very prominent ribs.Fil: Kihn, Romina Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); ArgentinaFil: Gomez, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); Argentina. Universidad Tecnológica Nacional. Facultad Regional Bahía Blanca; Argentin