Northwestern Argentina Research Articles

A long fossil trackway assigned to an ungulate from the Chiquimil Formation (Late Miocene, Messinian), Santa María valley, Catamarca, Argentina

The late Neogene sediments in northwestern Argentina have yielded a rich assemblage of fossil vertebrate remains, primarily consisting of skeletal elements. While these remains have provided valuable information, incorporating other types of evidence could further deepen our understanding of past communities. In this contribution, we study fossil trackways preserved in the Chiquimil Formation (Late Miocene, Messinian) of the Santa María valley, Catamarca Province, Argentina. The footprints exhibit a tridactyl morphology with distinctive features (e.g., U-shaped concavity on the posterior margin, central digit longer than the lateral digits), which has allowed their attribution to Macrauchenichnus cf. M. troyana. This finding is one of the longest and best-preserved trackway assigned to this ichnotaxon. The morphology and estimated body mass of the trackmaker align with hypotheses suggesting macraucheniid litopterns as producers, representing the first evidence of these ungulates in the area. This finding not only expands our knowledge of the paleobiodiversity of the region but also presents a unique opportunity for educational and ecotourism initiatives. The accessible location of the trackway and its potential for promoting scientific knowledge and local development make it a valuable resource for the community.

Has grey literature a value in conservation? The Case of Queñoa Polylepis spp. in Northwestern Argentina

Has grey literature a value in conservation? The Case of Queñoa Polylepis spp. in Northwestern Argentina

A new species of Andean rosulate Viola (subg. Neoandinium, Violaceae) endemic to the Puna of north-western Argentina

A new Andean rosulate species of Viola from the Puna of north-western Argentina, V. watsoniana, is described and illustrated here. The new discovery is compared with morphologically and geographically related species within subgenus Neoandinium. Their similarities and differences are discussed, including photos and a species key to distinguish between them in the context of section Rosulatae, in which V. watsoniana is provisionally placed. We also determine the potential conservation status of the new species as Critically Endangered (CR). Thus, V. watsoniana joins the constantly growing list of known species for Andean rosulate violets and contributes to understand part of the morphological and taxonomic diversity of subgenus Neoandinium.

In splendid isolation: a new cloud forest species expands the distribution of Myrceugenia (Myrtaceae) into Las Yungas and adds a new genus to the flora of Bolivia

Myrceugenia is a temperate or subtropical genus of c. 50 species with a disjunct distribution across South America. The ‘western’ species occur in central Chile and north-western Argentina with one species in the Juan Fernández Islands. The ‘eastern’ species occur in Uruguay, southern Brazil, and marginal regions of Argentina and Paraguay, reaching montane eastern Brazil (two isolated taxa in Central Brazil). It is hypothesized that Myrceugenia once grew across the temperate forests of southern South America, but that oceanic transgressions and the elevation of the Andes during the Miocene divided its populations as the forests retracted from the centre of the continent. The Las Yungas floristic province is a strip of cool, temperate forest that runs along the eastern slopes of the Andes from Venezuela to northern Argentina; Myrceugenia was not known to occur there. We report the discovery of a new species of Myrceugenia in southern Las Yungas (Bosque Tucumano Boliviano). It is distinct from all other species of the genus by the combination of solitary flowers, sub-ancipitate hypanthium, bilocular locules, and 12-13 clustered ovules. The phylogeny of Myrceugenia shows geographic structuring with three basal western clades and one derived eastern clade. The isolated taxa of Myrceugenia from Central Brazil were sisters, respectively, to the rest of the eastern clade and to one of its two subclades, suggesting that isolated taxa are relictual. The discovery of this species has made Myrceugenia the only genus of Myrtaceae to grow in the three cool, humid forests of southern South America.

Description of Timogenes pipanaco sp. nov., (Scorpiones, Bothriuridae) a new salt flat species from north western Argentina.

We describe Timogenes pipanaco sp. nov. (Scorpiones, Bothriuridae) from north western Argentina. This species is most similar to Timogenes haplochirus Maury & Roig Alsina 1977, both sharing a shallow internal excavation in pedipalp chela of males. This is the smallest known species of the genus with males averaging 33.3 mm, and is the only species of the genus with extremely reduced stridulatory organ. This species is apparently endemic to the Pipanaco salt flat in arid north western Argentina, and is active in spring. This is the first species of genus Timogenes described after 45 years.

Exploring local lignocellulosic substrates for the production of edible mushrooms in Northwestern Argentina

La Rioja province annually produces approximately 75,000 tons of agricultural residues and derived materials from agro-industrial activities, which could potentially be incorporated into oyster mushroom cultivation. This study aimed to evaluate the viability of this lignocellulosic biomass as a substrate for the cultivation of edible mushrooms belonging to the genus Pleurotus. Initially, the mycelial growth of two species (P. ostreatus and P. djamor) was assessed by formulating combinations of local substrates. Experimental crops were grown employing the most promising substrates, which were subsequently selected for chemical characterization. It was found that both strains exhibited maximum mycelial growth in the substrate formulated with jojoba leaf litter. A comparison of the two strains revealed no direct correlation between mycelium growth and productive performance. The highest biological efficiency (BE) values were obtained when P. ostreatus was cultivated in treatments combining jojoba leaf litter and grape pomace with olive pomace. Furthermore, these treatments showed suitable chemical properties and were formulated from problematic waste generated in large quantities in the region without proper processing and disposal methods. In this context, there is potential to ensure a continuous supply of this lignocellulosic biomass for cultivating these mushroom species over an extended period of time, thus providing a sustainable alternative for these regional by-products.

Small Mammal Trackways from the Neogene Vinchina Basin, Argentina: Insights into Xenarthra (Dasypodidae), Notoungulata (Typotheria), and Rodentia (Caviomorpha)

—Neogene deposits of northwestern Argentina host an outstanding ichnological record of the Cenozoic vertebrate faunas developed within a context of continental isolation in South America. The Vinchina (Middle to Late Miocene) and Toro Negro (Late Miocene to Early Pleistocene) formations, at La Rioja Province, have enhanced our understanding of these faunas for over the last 15 years. This contribution aims to explore and report the diversity of trackmakers responsible for five small mammal trackways. Four ichnospecies have been identified, of which three are new. Pichipoda igen. nov. has didactyl to monodactyl manus and tridactyl mesaxonic pes impressions with robust digits with blunt tips. Pichipoda manganae igen. nov. isp. nov. has didactyl manus and is the largest ichnospecies and Pichipoda vizcainoi igen. nov. isp. nov. has almost monodactyl manus impressions. They are interpreted as produced by armadillos (Xenartha: Dasypodidae), specifically P. vizcainoi most likely by tolypeutines (Tolypeutinae), with a trunk length of 21-23.5 cm, and an inferred body mass of 14.7 kg and 8.64 kg, respectively. Fossil armadillo footprints were unknown until now. Tridactylonicha marsicanae igen. nov. isp. nov., has tridactyl to didactyl paraxonic manus and tridactyl mesaxonic pes impression with long, slender, and pointed tips, they are interpreted as produced by hegetotheriids (Notoungulata: Typotheria: Hegetotheriidae) with a body mass of 3.7 kg, and a trunk length of 14 cm. Finally, it is recognized an extensive and complete trackway assigned to Dolichotichnus marae, with tetradactyl paraxonic manus and tridactyl mesaxonic pes impressions, representing an animal of 10.3 kg and a trunk length of 15 cm, is most likely produced by dolichotines (Rodentia: Caviomorpha: Caviidae). These findings provide new records of footprints previously unknown of small mammals, complementing our knowledge of the anatomical traits of small xenarthrans and some of the smallest extinct native ungulates.

Compound Hot and Dry Events in Argentina and Their Connection to El Niño‐Southern Oscillation

ABSTRACTThis work studies the simultaneous and sequential occurrence of hot and dry months in the summer season in Argentina, north of 40°S, based on three different databases: meteorological stations, a gridded observational dataset and a reanalysis product. The influence of the El Niño‐Southern Oscillation (ENSO) over the occurrence of these compound events is specially analysed using a logistic regression model. Monthly maximum temperature and precipitation data are used for the period 1979–2022 in four sub‐regions of Argentina: Northwestern Argentina (NOA), Northeastern Argentina (NEA), Cuyo (central‐western Argentina) and the Pampas (central‐eastern Argentina). Simultaneous hot and dry months and hot months preceded by dry months are the most frequent compound events. The highest frequencies are found in the centre part of the study region and NEA for simultaneous compound events, and in NOA and the Pampas region for sequential ones. In general terms, all datasets show a good representation of the spatio‐temporal variability of hot and dry months. The insights of the influence of ENSO on compound events revealed that La Niña enhances the occurrences of hot and dry months throughout the study region, with the exception of NOA, where El Niño conditions promote the occurrence of these events. Based on logistic regression models, we successfully quantify the relationship between ENSO and hot and dry months and demonstrate that ENSO plays a significant role as a driver of compound hot and dry events in the central region, Cuyo, NEA and a portion of the Pampas. This research contributes to the understanding of compound events in Argentina and how they are influenced by major drivers of climate variability providing useful information for the development of a predictive system for such events.

Ontogeny and associated changes of the extinct sloth Simomylodon uccasamamensis (Xenarthra, Mylodontidae) from the Pliocene of the eastern Puna, Argentina.

Within Xenarthra (Eocene-Recent), Folivora developed (late Eocene-Recent) a remarkable diversity with respect to ecology and taxonomy over its evolutionary history. Knowledge of the diversity achieved by members of this clade in high-altitude areas of South America (i.e., Altiplano and Puna regions of Peru, Bolivia, and northwestern Argentina) has been improved in recent decades. A particular example involves the late Neogene Mylodontidae Simomylodon uccasamamensis, known mostly from multiple specimens recovered from the Bolivian Altiplano. Although several anatomical descriptions of this ground sloth have been published, almost nothing is known about its ontogenetic development and the associated morphological changes. Here we describe and compare new specimens of S. uccasamamensis from the upper level of the Tafna Formation (Pliocene) in the eastern Puna (ca. 3800 masl), Argentina, representing the southernmost record of this species. The new material is represented by specimens showing different ontogenetic stages, from infant to adult. One subadult specimen reached an estimated body mass of ca. 232 kg. The comparative study of external and internal morphology (the latter obtained from CT scans and radiography) shows remarkable changes in the mandible and molariforms associated with ontogeny; in addition, evidence suggests that the mfs2-3 are the first functional teeth, followed by mf1 and cf1. Based on our body mass estimates (ca. 232 kg.), we inferred an average lifespan of 14 years, 9-month gestation time, and sexual maturation at 4.1 years, quite similar to the values we obtained based on estimated body masses of adult specimens from Bolivia published by previous authors. Along its latitudinal distribution (ca. 14° S-21° S) S. uccasamamensis co-occurred with other ground sloths (e.g., Megatheriinae, Thalassocninae, and Scelidotheriinae), suggesting niche partitioning. The presence of this medium-sized ground sloth is consistent with the similarity between the faunas of eastern Puna and the Bolivian Altiplano during the Pliocene, which is also concordant with what was observed in other clades, such as Rodentia and Notoungulata.

Wild rodent fleas carrying Bartonella and Rickettsia in an area endemic for vector-borne diseases from Argentina.

Vector-borne diseases account for nearly 20% of all globally recognised infectious diseases. Within the spectrum of flea-borne pathogens, Bartonella and Rickettsia bacteria are prominent, contributing to the emergence and resurgence of diseases on a global scale. This study investigates the presence of species of Bartonella and Rickettsia harboured by fleas collected from wild rodents in northwestern Argentina (NWA). A total of 28 fleas from three genera and seven species were assessed. DNA of Bartonella and Rickettsia spp. was found in 12 fleas (42.8%). Phylogenetic analysis of concatenated sequences of gltA and rpoB genes showed the presence of Bartonella quintana in eight fleas of two species, Craneopsylla minerva minerva and Polygenis acodontis. Phylogenetic analysis of concatenated sequences of gltA, ompA and ompB genes identified Rickettsia felis in ten fleas of five species, C. m. minerva, P. acodontis, Polygenis bohlsi bohlsi, Polygenis byturus and Tiamastus palpalis. These bacterial species mark the first report in all flea species studied. This study represents the first survey of flea-borne bacteria for NWA. The results provide information to address strategies for the control and prevention of bartonellosis and rickettsiosis that could have an impact on public health in one of the geographical areas of Argentina with the highest incidence of infections transmitted to humans by ectoparasites.

Social interaction between the coast and the highlands of Chile's arid north (20°S) during the mid‐Holocene: The case of Vicugna vicugna (Molina, 1782) and Hippocamelus antisensis (d'Orbigny, 1834)

AbstractThis article discusses the archaeological implications of the discovery of the highland species Hippocamelus antisensis (Cervidae) and Vicugna vicugna (Camelidae) in two coastal contexts in the Atacama Desert (20°S, Chile). H. antisensis is currently distributed throughout the Peruvian Andes, northern Chile, western Bolivia and northwestern Argentina, between 1800 and 5500 m above sea level. V. vicugna is distributed throughout northern Peru and northwestern Argentina, in environments that exceed 3200 m above sea level. The archaeological record of deer antlers on the Atacama coast has previously been documented at the Caleta Huelén‐42 site (21°S). In the case of V. vicugna, fibers have been recovered only at the coastal site of Camarones‐14 (19°S). A dating of 4180 ± 20 year BP obtained from V. vicugna bone and indirect dating of the antlers suggest an early social exchange between groups from coastal regions and those from the Atacama Desert Mountain range, as well as encourage to the potential record of remains/products of these animals in areas far from their natural habitats.

Hantavirus Pulmonary Syndrome Outbreak Anticipation by a Rapid Synchronous Increase in Rodent Abundance in the Northwestern Argentina Endemic Region: Towards an Early Warning System for Disease Based on Climate and Rodent Surveillance Data.

Hantavirus pulmonary syndrome (HPS) is an American emerging disease caused by the rodent-borne virus genus Orthohantavirus (Family: Hantaviridae: Order: Elliovirales Class: Bunyaviricetes). In Argentina, almost half of the HPS infections occur in the northwestern endemic region. In this study, we monitored rodent abundance during 2022 and 2023 in three sites with different sampling methods (removal trapping, live trapping and hunted rodents by domestic cats) to evaluate their relationship with human infections. We found a similar pattern of variation in rodent abundance across time, and particularly a synchronous rise of rodent abundance that anticipated an HPS outbreak in 2023. Our dynamic regression models revealed a positive relationship between HPS cases and rodent abundance with a three-month lag, as well as rainfall with an eight-month lag. Our results provide a framework for the planning and implementation of public health prevention campaigns based on climatology and rodent monitoring. Domestic cats bringing rodents into houses can be an overlooked risk factor, particularly if viral shedding of infected rodents is magnified by stress. HPS is a disease of public health concern due to its high mortality rate, the lack of a specific therapeutic treatment and no vaccine. Thus, prevention of infections is of the utmost importance.

Plohophorini glyptodonts (Xenarthra, Cingulata) from the late Neogene of northwestern Argentina. Insight into their diversity, evolutionary history, and paleobiogeography

Plohophorini glyptodonts (Xenarthra, Cingulata) from the late Neogene of northwestern Argentina. Insight into their diversity, evolutionary history, and paleobiogeography

Redescription of a small Caviidae (Rodentia: Hystricognathi) from the Neogene of northwestern Argentina and its systematic implications

Redescription of a small Caviidae (Rodentia: Hystricognathi) from the Neogene of northwestern Argentina and its systematic implications

Seasonally dry tropical forests in the late Pleistocene of Mesopotamia, Argentina and their relationship to environmental changes during the Last Interglacial

ABSTRACTThe concept of seasonal forests groups structural types of vegetation that are related to climatic seasonality in the tropics of South America. Consequently, this determines the physiognomy of the vegetation, from semi‐deciduous to strongly deciduous. The strongest link between seasonally dry tropical forests (SDTFs) is their floristic composition, where Leguminosae and Anacardiaceae dominate the woody flora. The fossil records of the Neogene of northwestern Argentina reveal a list of species found in various locations and formations of the Miocene–Lower Pleistocene obtained from studies of pollen, woods (logs), cuticles, impressions of leaves and fruits. The analysis of sediments and woody structures from the Tapebicuá, Toropí/Yupoí and El Palmar Formations (Upper Pleistocene) of the Mesopotamia region allowed us to identify several pollen taxa and silicified wood fragments (mineralized). The woody and shrubby association whose current relatives characterize the SDTF is composed of the 16 fossil species described here belonging to seven families. In our samples, Anadenanthera colubrina and Myracrodruon balansae are the most significant members of the families Leguminosae and Anacardiaceae, which are dominant in the SDTF. The paleobotanical species described in this study confirm the extension of the SDTF to the province of Corrientes, coinciding with various climatic events (dry subtropical, semi‐desert and warm‐humid climate) that would have favored the development of these forests during the Pleistocene in this region. The absolute dates obtained for the Toropí/Yupoí and Tapebicuá Formations confirm their synchronicity and correlation to Marine Isotope Stage 5. The palynological analysis, the presence of Menendoxylon and the sedimentological data allow us to infer the existence of a seasonally dry humid paleoclimate in northeastern Argentina during the Late Pleistocene favorable to the development of the SDTF.

Comparison of parasitological methods for the identification of soil-transmitted helminths, including Strongyloides stercoralis, in a regional reference laboratory in northwestern Argentina: An observational study

Soil-transmitted helminths (STH) are a significant public health problem in impoverished communities of tropical and subtropical areas. Improved diagnostic methods are crucial for Neglected Tropical Diseases programs, particularly for S. stercoralis, as traditional methods are inadequate. Thus, it is important to identify the most accurate and efficient methods for the diagnosis of STH. We performed a retrospective study analyzing laboratory data at the Instituto de Investigaciones de Enfermedades Tropicales from 2010 to 2019. The study included data from outpatients referred for stool analysis and public health interventions from urban and rural communities in northern Salta province, Argentina. Samples were included in this analysis if processed through sedimentation/concentration, Baermann, Harada-Mori and McMaster's, with a subgroup that also included Agar plate culture method (APC). Sensitivity was calculated against a composite reference standard. Of the 5625 samples collected, 944 qualified for this analysis, with a prevalence of 11.14% for A. lumbricoides, 8.16% for hookworm, 1.38% for T. trichiura, and 6.36% for S. stercoralis. The sedimentation/concentration method was the most sensitive for A. lumbricoides (96%), compared to the McMaster method, with a sensitivity of 62%. Similarly, for hookworms, sedimentation/concentration was more sensitive than McMaster's, Harada-Mori, and Baermann with sensitivities of 87%, 70%, 43%, and 13%, respectively. Most of these infections were of light intensity. For S. stercoralis, Baermann and sedimentation/concentration methods were the most sensitive, with 70% and 62% respectively, while Harada-Mori was the least sensitive. In a subset of 389 samples also analyzed by the APC, Baermann was more sensitive than APC for detecting S. stercoralis, and both methods were superior to Harada-Mori. Parasitological methods, mostly when used combined, offer adequate opportunities for the diagnosis of STH in clinical and public health laboratories. The incorporation of S. stercoralis into the control strategies of the World Health Organization requires rethinking the current diagnostic approach used for surveys. With sedimentation/concentration and Baermann appearing as the most sensitive methods for this species. Further studies, including implementation assessments, should help in identifying the most adequate and feasible all-STH diagnostic approach.

The two southernmost species of the Andean genus Acrographinotus Holmgren (Arachnida, Opiliones, Gonyleptidae) described from Bolivia and Argentina.

Two new species of the genus Acrographinotus (Opiliones, Laniatores, Gonyleptidae) are described from protected areas placed on sub-Andean ranges: Acrographinotus tariquiae sp. nov. from Tariquía National Reserve, southern Bolivia, and A. calilegua sp. nov. from Calilegua National Park, northwestern Argentina. They represent the southernmost representatives, and in the case of A. calilegua sp. nov., the lowest altitudinal record of this wide-ranged Andean genus. Acrographinotus tariquiae sp. nov. is compared with its most similar congeners, A. erectispina (type species) and A. niawpaq, from which it differs by the armature of trochanter IV, femur IV and ventral anal plate of the male. Differences between A. calilegua sp. nov. and A. tariquiae sp. nov., especially considering small-sized and β-type males of the latter, are detailed. The genus diagnosis is updated. A key to identify males of the nine confirmed nominal Acrographinotus species is provided for the first time.

Nephrosis in cattle associated with consumption of Ludwigia peploides (Onagraceae)

This paper describes an outbreak of nephrosis in cattle associated with the consumption of Ludwigia peploides in Tucuman province, northwestern Argentina. Affected cows exhibited submandibular and chest edema, lethargy and ataxia, and eventually succumbed to these conditions. These animals were grazing in a floodable area severely invaded by this plant. The disease affected 7 out of a herd of 67 cows. Horses and goats grazing in the same location were not affected. The main gross and histological lesion corresponded to a severe nephrosis. The disease is similar to the poisoning by Ludwigia peruviana reported in Colombia.

Biological control of soybean charcoal rot by native Trichoderma koningiopsis in Tucumán, Argentina

Macrophomina phaseolina (Tassi) Goid. (Mp) is the causal agent of charcoal rot in soybean, an economically serious and potentially destructive disease. Chemical control sometimes has limited effects on disease severity and may pose a threat to the environment, so the use of Trichoderma as a biological product could be a feasible alternative for charcoal rot management. The objective of this research was to isolate and characterize native Trichoderma spp. from northwestern Argentina and study their antagonistic effect against Mp in soybean. Isolations were performed from soil samples followed by cultural and microbiological characterization of the Trichoderma spp. isolates collected. Then, the antagonist effect against Mp was studied in vitro, under greenhouse conditions, and finally under field conditions with pathogen artificial inoculations during two soybean crop seasons (2020 and 2021). The results demonstrated that isolate Tr009 had a biocontrol effect against Mp in soybean. This control was evidenced in vitro and under controlled and field conditions with high emergency of plants compared to the Mp inoculated control. Under field conditions, treatments that included Trichoderma presented lower disease severity, colony-forming unit index and disease severity index values than the pathogen inoculated control. Moreover, Tr009 improved weight and length of soybean plants under greenhouse conditions. Isolate Tr009 was identified as Trichoderma koningiopsis by molecular methods. These results indicate that this biological tool can be used against Mp and thus favor a sustainable management of soybean charcoal rot.

Eocene exhumation of the High Andes at ~30°S differentiated by detrital multimethod U-Pb-He thermochronology

Abstract The southern Central Andes (~25–40°S) exhibit a complex tectonic history, crucial for understanding orogenic processes in subduction-related orogens, yet debate on the timing and mechanisms of early Cenozoic topographic growth persists. We present double-dated detrital zircon U-Pb and (U-Th)/He thermochronology data from the early Oligocene–Miocene Bermejo Basin at ~30°S to investigate source unroofing during development of the High Andes. (U-Th)/He results yield dates of ca. 565–16 Ma (n = 73), with distinct detrital modes that indicate a mixing of sediment sources characterized by variable cooling and exhumation histories. We employ a novel approach for modeling detrital thermochronology data that leverages the shared basin subsidence history of multiple detrital modes to resolve provenance and source unroofing histories. Results from the lower Oligocene Vallecito Formation (northwestern Argentina) reveal that detritus was sourced from Permian–Triassic Choiyoi Group rocks that underwent rapid late Eocene cooling, indicated by short lag time (2–5 m.y.) between source cooling and deposition. Our findings are consistent with bedrock studies of Eocene exhumation in the High Andes and establish source-to-basin connectivity during this time. Other detrital modes with pre-Cenozoic cooling histories were derived from Carboniferous Elqui-Colangüil and Choiyoi Group rocks or recycled from Paleozoic basins. We propose that an early Oligocene drainage divide in the High Andes was located west of the Punilla–La Plata fault, an active thrust front at ~30°S. These findings challenge Paleogene neutral stress-state models for the Andes and underscore the importance of improved knowledge of erosion and deformation histories for refining models of Andean orogenesis.