Northern Argentina Research Articles

The poly-orogenic Paleozoic rocks of Cuesta del Rahue area (Precordillera Neuquina, Argentina) and their significance in marking the southern end of the Chanic orogenic belt

In the Cuesta del Rahue area, located in the Precordillera Neuquina (northern Argentine Patagonia), late Paleozoic turbiditic rocks with maximum depositional age of ca. 389 Ma were affected by three orogenic events. The oldest orogenic event is the Chanic orogeny (Late Devonian–early Carboniferous) that is characterized by folds with NNE vergence. This deformation is developed in low-grade to very low-grade metamorphic conditions, which allowed the development of a slaty/rough cleavage. The main Chanic structure is an asymmetric fold with a large normal limb tilted by the more recent orogenic events. The characteristics of the deformation and metamorphism allows us to assign the Cuesta del Rahue outcrop to the external hinterland of the western wedge of the Chanic orogen. Early to late Carboniferous igneous rocks intruded the Paleozoic rocks of the Cuesta del Rahue area and crosscut the Chanic structures. After the Chanic orogeny, the Gondwanan orogeny (late Carboniferous–early Permian) took place. The main structures of the Gondwanan orogen are thrust and related folds with SSW vergence that fold the large Chanic normal limb and also affect Carboniferous igneous rocks. The Gondwanan deformation was developed under non-metamorphic conditions, and Permian igneous rocks crosscut the Gondwanan structures. Mesozoic regional extension related to the beginning of the Andean cycle and the formation of the Neuquén Basin gave rise to normal faults and small-scale extensional folds. Finally, the Andean orogeny, developed during the Cenozoic in the study area, also affected the Cuesta del Rahue Paleozoic rocks, with the development of compressional structures related to the Aluminé thrust and fold belt. The main Andean structure in the study area is the NW–SE Rahue fault, which links the E–W Piedra Santa tear fault with the NNE–SSW Catán Lil reverse fault. The Rahue fault has a SW tectonic transport direction. It uplifted the Cuesta del Rahue area and placed Paleozoic rocks on top of Mesozoic and Cenozoic rocks. The Piedra Santa fault partially reactivated the Huincul right-lateral and left-lateral Chanic transverse faults that define the southern end of the doubly vergent Chanic orogen, giving rise to the current Huincul lineament.

Evolution of complex giant seafloor depressions at the northern Argentine continental margin (SW Atlantic Ocean) under the influence of a dynamic bottom current regime

Seafloor depressions (SD) are features commonly observed on the ocean floor. They often occur as circular, small-sized (up to 10 s of m) incisions caused by fluid expulsion. Larger depressions (100s m to km) are considerably less abundant, and their origin and development have been scarcely studied. This study investigated two giant morphological depressions (>5 km) using recently acquired multibeam bathymetry and backscatter, sediment echosounder, and high-resolution seismic data. An arc-shaped (SD-N) and a sub-circular depression (SD-S) are located on the Ewing Terrace at the Argentine Continental Margin north and south of the Mar del Plata Canyon, respectively. The study area is influenced by the Brazil-Malvinas Confluence, where major counterflowing ocean currents affect sedimentation, and northward flowing currents form a large contourite depositional system. Using an existing seismo-stratigraphy, the onset of SD-N was dated to the middle Miocene (∼15–17 Ma), whereas SD-S started developing at the Miocene/Pliocene boundary (∼6 Ma). Acoustic anomalies indicate the presence of gas and diffuse upward fluid migration, and therefore seafloor seepage is proposed as the initial mechanism for SD-S, whereas we consider a structural control for SD-N to be most likely. Initial depressions were reworked and maintained by strong and variable bottom currents, resulting in prograding clinoform reflection patterns (SD-N) or leading to the build-up of extensive cut-and-fill structures (SD-S). Altogether, this study highlights the evolution of two unique and complex seafloor depressions throughout the geologic past under intense and variable bottom current activity in a highly dynamic oceanographic setting.

Identification of coronaviruses in bats and rodents in northern and central Argentina.

Due to the present pandemic situation and the many animal species that are epidemiologically involved, there has been a surge of renewed interest in investigating the coronavirus (CoV) population circulating in wildlife, especially bats and rodents, which are potential reservoirs of new human pathogens. In Argentina, information about the viruses present in these mammals is very limited. To investigate the presence of coronaviruses in this country, we obtained 457 samples from hematophagous, insectivorous, and frugivorous bats and rodents from two regions of Argentina. We report here the detection of alphacoronavirus sequences in three groups of bats as well as in rodents. Phylogenetic analysis showed the closest relationships to alphacoronaviruses from Brazil.

Do parapatric populations of the ticks Amblyomma tonelliae Nava, Beati & Labruna, 2014 and Amblyomma sculptum Berlese, 1888 (Acari: Ixodidae) hybridize?

This work aimed to determine if the tick species, Amblyomma sculptum and Amblyomma tonelliae, hybridize along their contact zones in Argentina. Free-living adults and nymphs of A. sculptum and A. tonelliae were collected in seven sampling locations of northern Argentina. In four of them, the two species occur in parapatry (possible hybrid zone) whereas in the other three sites, only one species is known to occur. A total of 65 A. sculptum and 65 A. tonelliae from both, allopatric and parapatric populations, were analysed. The nuclear (ITS2) and mitochondrial (COI and 12SrDNA) gene sequences of each tick were amplified and analysed to verify whether or not they could reveal the presence of hybrids among the parapatric samples. No morphological and molecular evidence was found to support the hypothesis of ongoing natural hybridization. Intrinsic postzygotic barriers may be the cause of lack of gene flow between the two species in areas of co-ocurrence. The results can be explained by the length of time the two lineages spent in allopatry since the middle of the Miocene and before their respective distribution range expanded again reaching a narrow secondary contact zone.

Phylogenetic relationships of the Amblyomma cajennense complex (Acari: Ixodidae) at mitogenomic resolution

The genus Amblyomma is the third most diverse in the number of species within the Ixodidae, with practically half of its species distributed in the Americas, though there are also species occurring in Africa, Asia, and Australia. Within the genus, there are several species complexes with veterinary and public health importance. The Amblyomma cajennense complex, in the Americas, is represented by six species with a wide distribution, from Texas to northern Argentina. We combined two sequencing techniques to generate complete mitogenomes of species belonging to the Amblyomma cajennense complex: genome skimming and long-range PCRs sequencing methods. Thus, we generated seven new mitochondrial genomes for all species of the Amblyomma cajennense complex, except for Amblyomma interandinum. Genetic distances between the mitogenomes corroborate the clear differentiation between the five species of the Amblyomma cajennense complex. The phylogenetic relationships of these species had previously been evaluated by combining partial nuclear and mitochondrial genes and here these relationships are corroborated with a more robust framework of data, which demonstrates that the conjunction of mitochondrial and nuclear partial genes can resolve close relationships when entire genes or genomes are unavailable. The gene order, structure, composition, and length are stable across these mitogenomes, and they share the general characteristics of Metastriata. Future studies should increase the number of available mitogenomes for this genus, especially for those species from the Indo-Pacific region and Africa, by means of a better understanding of their relationships and evolutionary process.

The Complete Genome Sequence of Sarcoramphus papa (Cathartidae), the King Vulture.

Sarcoramphus papa is a New World Vulture found predominantly in tropical lowland forests stretching from southern Mexico to northern Argentina. We present the whole genome sequence of this species. Illumina paired-end reads were assembled by a de novo method followed by a finishing step. The raw and assembled data are publicly available via GenBank: Sequence Read Archive (SRR19167646) and assembled genome (GCA_027580115).

Species boundaries in Lippia asperrima and Lippia turnerifolia complex (Verbenaceae)

Species boundaries in Lippia asperrima and Lippia turnerifolia complex (Verbenaceae)
 The specific boundaries of Lippia asperrima and L. turnerifolia are discussed. Lippia contermina is accepted as segregated of L. asperrima, while L. modesta and L. Morongii are rehabilitated of the synonym of L. turnerifolia. Lantana ovata and Lippia contermina var. hirsuta are recognized as new synonymies of Lippia contermina, whereas Lippia trachyphylla is treated as cospecific of L. modesta, and L. asperima f. angustifolia is reduced under L. Morongii. All treated species are described and illustrated, and information on taxonomic relationships and morphological limits are discussed. A Dichotomous key for distinguishing the species of Lippia sect. Dioicolippia is proposed. Lippia sect Dioicolippia comprises 21 species distributed mainly in southern and centralwestern Brazil, northeast and northern Argentina, Paraguay and Uruguay.

Lithium mining, water resources, and socio-economic issues in northern Argentina: We are not all in the same boat

Lithium mining in Argentina is often associated to social injustices, unequal access to information, and conflicts around issues such as water consumption. Different stakeholders hold different perceptions around the pros and cons of lithium mining. We identify here concerns regarding water resources, technical aspects of lithium mining, and social and economic aspects in four different sources of information: (1) Scientific articles; (2) Government reports; (3) Corporate reports; and (4) Newspaper articles. We found differences between the groups of documents analyzed. Scientific and newspaper articles share a wide spectrum of issues. Corporate and government reports are more focused and relate more heavily to social and economic aspects. Socio-technical issues, frequent in government reports and the media, do not seem relevant in corporate reports. Concerns about water resources and lithium mining are most prominent in scientific and newspaper articles. Government reports were the least concerned about water and the socio-environmental impacts of lithium mining, but focused on global markets, employment and technical development. Analyzing stakeholders’ concerns in the Argentine Puna region can help reveal power structures, connections, and discourses across different sectors and scales.

Short-Term Meteorological Conditions Explain Cyanobacterial Blooms in a Tropical Reservoir

Cyanobacterial blooms represent a major problem in reservoirs that are used for potable water supplies. The El Limón reservoir is one of the main reserves of water for consumption in northern Argentina (22°6′12.29″ S). This study analyzed the role of abiotic factors in the promotion of blooms in El Limón during warm seasons and explored the physical and chemical parameters affecting the morphological development of the most abundant cyanobacteria species. The results showed that short-term meteorological variations correlated with cyanobacterial abundances in this shallow reservoir. Average daily temperatures for 6 and 8 months before the sampling date were positively correlated with cyanobacterial abundances as well as filament length, while accumulated precipitation limited the abundances of cyanobacteria. Considering the highly probably effects of short-term meteorological factors on cyanobacterial blooms, the results support the need for continuous and periodic monitoring of tropical reservoirs.

A noteworthy new record of Gray-bellied Hawk, Accipiter poliogaster (Temmink, 1824) (Accipitiformes, Accipitridae), in the lowlands of northern Costa Rica

Gray-bellied Hawk, Accipiter poliogaster (Temmink, 1824), is a rare forest dwelling raptor in South America. This hawk migrates from Paraguay and northern Argentina (Misiones) in the south to the equator for the winter. In Costa Rica this species has occasionally been recorded from a few localities. We present here a new record from a disturbed area in the northern lowlands of the country. Accipiter poliogaster may be a rare vagrant or an occasional visitor in Costa Rica, or it may be expanding its range northward into the country due to increases in disturbed land caused by humans.

Aristolochia stevechurchillii, a new pseudostipule-bearing Aristolochiaceae (Piperales) from Bolivia, with a key to identify the species of the ´Pseudostipulosae´ group in the country

A new pseudostipule-bearing species of Aristolochia, A. stevechurchillii, is here described and illustrated, along with a key to identify all the species of the informal ´Pseudostipulosae´ group naturally occurring in Bolivia. The new species differs from its closely related species by the formation of two serial flowers per axil, the base of the utricle with six retrorse digitiform processes, and the perianth limb narrowly ovate, with acute apex. Along with A. andina and A. lozaniana, A. stevechurchillii is the third species of the genus endemic from mid-elevation (1600-2500 m) Tucumano-Bolivian forests of the departments of Cochabamba, Chuquisaca and Tarija (Bolivia). The new species is morphologically similar to A. melanoglossa, from northern Argentina, which provides additional evidence to floristic affinities previously proposed between the Tucumano-Bolivian forests and the Chaco vegetation.

Novos registros de espécies de Ceratocampinae (Lepidoptera: Saturniidae) para o Cerrado do Maranhão, Brasil

Abstract Ceratocampinae (Lepidoptera: Saturniidae) is the second most diverse subfamily of Saturniidae with 300 species described in 30 genera from southern Canada to northern Argentina. Species of this subfamily are widely distributed in Southeast Brazil, with many endemics to the Cerrado, and important as indicators of ecosystem quality. Specimens of Ceratocampinae were collected in the Parque Estadual do Mirador, Maranhão state, Brazil. Adeloneivaia acuta (Schaus, 1896), Adeloneivaia schubarti Barros & O. Mielke, 1970, Eacles penelope (Cramer, 1775) and Megaceresa pulchra (Bouvier, 1923) are recorded for the first time in Maranhão state and Northeast Brazil and Eacles fairchildi May & Oiticica, 1941, only for Maranhão. The record of five Ceratocampinae (Saturniidae) species increases the knowledge on the diversity and the importance of preserving those of this subfamily in the Cerrado biome of Maranhão state and the Northeast region of Brazil.

Sex-specific migratory behavior in a marine predator results in higher risks to females

Protecting migratory species requires knowledge of their distributions throughout the year. Spatial or temporal segregation of females and males during part of the annual cycle complicates conservation measures and can lead to sex-biased mortality. Females and males of many seabird species use separate areas during the nonbreeding season, and sex-biased bycatch in fisheries is common. We satellite-tracked 8 female and 8 male post-breeding adult Magellanic penguins Spheniscus magellanicus, including 7 pairs, from Punta Tombo, Argentina, during their fall northbound migration. Our results agreed with recent studies from other colonies, and provided more accurate locations than the geolocator tags used in those studies. Females stayed 47 km closer to shore than males. On average, females and males reached similar latitudes from northern Argentina to southern Brazil. Females tended to stay farther north, however, with some males heading south by June. Body size did not influence how far offshore a penguin migrated, when controlling for sex. On average, females left the colony 2 d before their mates, and did not encounter them at sea. The mean distance between mates at sea was more than 350 km. Females are likely exposed to fishing gear and pollution more than males because the females stayed closer to shore and stayed farther north than males. Migratory routes varied among individuals. The large area that penguins use during their nonbreeding season makes protection of the population difficult.

Melissopalynology of <i>Coffea arabica</i> honey produced by the stingless bee <i>Tetragonisca angustula</i> (Latreille, 1811) from Alajuela, Costa Rica

<abstract> <p><italic>Tetragonisca angustula</italic> is the most widespread stingless bee species, from Mexico to Northern Argentina. It is called Mariola in Costa Rica. Native plant species offering food resources and nesting sites to stingless bees are included in reforestation and conservation programs. In Costa Rica there are continuous initiatives on listing flora supporting meliponiculture. In this study, a sample of pot-honey was collected from sealed honey pots within nests of <italic>Tetragonisca angustula</italic> in Alajuela, Costa Rica. It was acetolyzed following standard methods and the pollen types were visualized by microscopic analysis at 200X magnification using a Nikon Eclipse Ni binocular scope. Electronic brightfield micro-photographs were obtained at 1000X magnification and pollen types were plated. Palynological descriptions were provided for major pollen grains. The botanical identifications of plant families and genera were established by comparison with pollen atlases and were validated consulting the 2022 Tropicos Missouri Botanical Garden database. Seventy-nine pollen types were recognized in the pollen spectrum, representing 36 families and 67 genera of flowering plants. Their habits were trees (51%), lianas/vine (11%), herbs (19%), herb/tree (5%), shrubs (5%), shrub/tree (1%) and not assigned (8%). This assemblage indicated the presence of lowland tropical forest elements, probably small relicts of secondary forest surrounding open and cultivated areas where <italic>Coffea arabica</italic> pollen dominated in the honey pollen spectrum with 54.3% of total counts, with secondary <italic>Paullinia</italic> sp. 8.7%, <italic>Vochysia</italic> sp. 4.8% and <italic>Cassia</italic> sp. 4.2% and 95% of pollen taxa present in < 3% relative frequency. Taxa offering only pollen (polleniferous) were considered honey contaminants (32%) not explaining the nectar botanical origin of honey.</p> </abstract>

Multiple colors in anteaters: review and description of chromatic disorders in Tamandua (Xenarthra: Pilosa) with reports of new and rare coat colorations

Tamandua Gray, 1825 contains two species of anteaters: Tamandua mexicana (Saussure, 1860), which occurs in southern Mexico, throughout Central America and south to the west of the Andes in South America, and Tamandua tetradactyla (Linnaeus, 1758), widely distributed in South America, from Venezuela to northern Argentina, as well as Trinidad and Tobago. Historically, different coloration patterns have been attributed to the coat of Tamandua, with T. mexicana typically showing a partial or complete dark “vest” on the dorsal portion of the body, whereas T. tetradactyla can show a complete, partial, or absent vest and a coat varying from golden, pale yellow and pale gray to brown or black. These different coat colors are sometimes treated as inherent characteristics of subspecies of Tamandua. Here, we review color variation in Tamandua and describe six chromatic disorders for the genus: albinism, leucism, “brown” variation, melanism (partial and total), xanthochromism (partial and total) and, for the first time for anteaters, erythrism. In addition, we detail the morphological expression and geographic distribution of these anomalies in populations of Tamandua from Central and South America.

Physical and biological effects on the carbonate system during summer in the Northern Argentine Continental Shelf (Southwestern Atlantic)

The Argentine shelf and its shelf-break (Southwestern Atlantic Ocean) are known for their high biological productivity, and as an important CO 2 sink region. However, many aspects of the carbonate system dynamics in the area, especially those related to the biological activity, deserve further study. Here we investigated the mechanisms affecting the carbonate system distributions, using in situ physical, chemical and biological observations collected along a section (COSTAL-AR) on the Northern Argentine Continental Shelf during two summer cruises in 2019. Our main goal was to evaluate the role of the microbial communities on the modulation of the carbonate system in the area. For that, we characterized (i) the distribution of the thermohaline properties, chlorophyll a , dissolved oxygen, carbonate system (pH, total alkalinity, dissolved inorganic carbon and high resolution underway CO 2 fugacity, fCO 2 ), dissolved inorganic nutrients, and (ii) the microbial communities (bacterioplankton, phytoplankton, and protozooplankton). Our results show that the COSTAL-AR section was likely an important CO 2 sink and presented high seawater fCO 2 spatial variability in both middle (272–430 μatm) or early (211–365 μatm) summer conditions. Phytoplankton played a key role in modulating the CO 2 uptake and carbonate system spatial variability during summer, especially in the middle and outer shelf. The main contribution to CO 2 fixation was given by small cells, since the microbial community was dominated by autotrophic picoplankton (<2 μm; e.g. Synechococcus sp. and coccal picophytoeukaryotes). Moreover, the influence of the Shelf-break front in ruling both the seawater fCO 2 distribution and biological processes was evident. These findings provide new insights on the connection between the biology and the carbonate system in this sparsely sampled area of the southwestern Atlantic Ocean. • New Argentine Shelf data analyzed biogeochemical mechanisms affecting the carbonate system. • The study region during the summer was likely an important CO 2 sink. • Biological mechanisms affected the CO 2 dynamics in the Argentine Shelf in summer. • Small phytoplankton (<2–3 μm) played a key role in modulating the CO 2 uptake.

Morphoanatomic characterization of Gomphrena perennis and Gomphrena pulchella leaves

Background Gomphrena perennis (Gpe) and G. pulchella (Gpu) are perennial glyphosate-tolerant amaranthaceous weeds of central and northern Argentina where glyphosate-resistant soybeans are grown with no-till. The study of weeds leaves morphoanatomy is important to understand environmental adaptation and could be used to explain herbicide absorption. Leaf surfaces of Gomphrena species were previously described for phylogenetic studies, and morphoanatomy of two Gomphrena perennis populations was characterized for glyphosate tolerance. There are no reports on comparative studies of Gpe and Gpu. [...]

Marine debris ingestion by odontocete species from the Southwest Atlantic Ocean: Absence also matter

In this paper, we examined the ingestion of large marine debris (1 mm–1010 mm) in 21 odontocete species that were found dead or by-caught in low frequency in southern Brazil (Rio Grande do Sul State) and northern Argentina (Buenos Aires) between 1988 and 2020. Eight percent of the total individuals studied (13 out of 156), representing nine species, had ingested marine debris. Most of items were made of plastics (68 %), and within them, single-use plastic (e.g. plastic bags) were the dominant man-made items. Seven of the nine species that had ingested marine debris have been previously registered ingestion of this pollutant in other areas of their distribution. We also incorporated endemic odontocetes of the Southwest Atlantic Ocean to the list of affected marine organisms: the Burmeister's porpoise Phocoena spinipinnis, and the Lahille's bottlenose dolphin, Tursiops gephyreus.

Constraining depositional evolution and reservoir compartmentalization in a mixed carbonate-siliciclastic lacustrine system: The Yacoraite formation, Salta Group, NW Argentina

The mixed carbonate-siliciclastic Yacoraite Formation, Salta Group in northern Argentina has been interest of recent studies searching for potential analogues for the South Atlantic pre-sal carbonates. Microbial lacustrine carbonates are important reservoir systems and their characteristics and stratigraphic packaging are a major factor impacting compartmentalization. This study provides sedimentological and facies analyses combined with petrographical, isotope geochemical and petrophysical analyses of lacustrine clastics and carbonates using an example from the Yacoraite Formation (Salta Group) in northern Argentina (Tres Cruces sub-basin).The Yacoraite Formation records the evolution of a lacustrine system responding to basin scale tectonic processes and climatic conditions and is interpreted as a microbially-related mixed carbonate clastic lacustrine system comprising 8 main Facies types, deposited in either a perennial or an ephemeral system. The most dominant architectural elements are: Sandstones with interbedded shales (F1), Shales with interbedded sandstones and siltstones (F2), Thick-bedded oolitic grainstone (F5), Thin-bedded oolitic grainstone-packstone (F6) and Stromatolite boundstone (F8). These facies types allow to differentiate two types of lacustrine environments: Perennial (Stage I) vs Ephemeral (Stage II) intercalated with episodes of continental plains deposition, arranged in three depositional sequences (Yacoraite I, II and III), each recording either transgressive or a regressive-transgressive trend.Carbonate and clastics are arranged in cycles during the Perennial l Stage suggesting that the depositional system responded in patterns attributable to reciprocal sedimentation, whereas, during the Ephemeral Stage 2, spatial coexistence of clastic and carbonate seem to be the case rather that cyclic vertical superposition.Thick-bedded oolitic grainstone and Stromatolites (F5 and F8 respectively) of the perennial lacustrine system show laterally continuous and thick beds with the best reservoir properties. Furthermore, the Sandstones with interbedded shales (F1) are characterized by intermediate values of porosity and permeability, which would not result in permeability barriers. On the other hand, Thin-bedded oolitic grainstone-packstone (F6) of the ephemeral lacustrine system are characterized by a high degree of heterogeneity due to their limited areal distribution and their complex spatial variability with Shales with interbedded sandstones and siltstones (F2).

New records of continental vertebrates from the Triassic of the Atacama Desert, northern Chile

This contribution describes new vertebrate remains found in Triassic strata informally known as “Estratos El Bordo”, in the Atacama Desert, northern Chile. These include the first temnospondyl record in the El Bordo Basin, plus actinopterygians referable to the clade Pseudobeaconiidae and a second form with affinities to the incertae sedis ray-finned fish Guaymayenia paramillensis. Associated to these taxa, we describe two spiral coprolites. Their vertebrate producers are discussed. These new freshwater vertebrates add to previous archosaur records from “Estratos El Bordo”, represented by the putative aetosaur Chilenosuchus forttae, an indeterminate silesaurid and a fragmentary indeterminate Crocodylomorpha. Vertebrate remains here described show affinities to the known diversity from the Cuyana Basin of Argentina, but differ from those recorded in northern Argentina (Ischigualasto-Villa Unión Basin) and southern Brazil (Paraná Basin). This suggests preliminary paleoenvironmental insights for the continental vertebrates that inhabited the southwestern margin of South America during the Triassic. The new findings also support a Middle-to-Upper Triassic age for the “Estratos El Bordo” unit, as previously indicated by radioisotopic datating.