Cobaltabis(Dicarbollide) [o-COSAN]− for Boron Neutron Capture Therapy of Head and Neck Cancer: Biodistribution and Irradiation Studies in an Experimental Oral Cancer Model Palmieri, Mónica Alejandra; Monti Hughes, Andrea; Trivillin, Verónica Andrea; Garabalino, Marcela Alejandra; Ramos, Paula Sofia; Thorp, Silvia Inés; Curotto, Paula; Pozzi, Emiliano C. C.; Nuez Martínez, Miquel; Teixidor, Francesc; Viñas, Clara; Schwint, Amanda Elena Boron neutron capture therapy (BNCT) is a tumor-selective particle radiotherapy that combines preferential boron accumulation in tumors and neutron irradiation. Based on previous studies in tumor-bearing mice, this study evaluated the biodistribution of the sodium salt of cobaltabis(dicarbollide) (Na[3,3´-Co(C2B9H11)2], abbreviated as Na[o-COSAN]) in the hamster cheek pouch oral cancer model and the Na[o-COSAN]/BNCT therapeutic effect on tumors and induced radiotoxicity. The synthesis and comprehensive characterization of 10B-enriched trimethylammonium salt of nido-[7,8-C210B9H12]-o-carborane, along with the cesium and sodium salts of [o-10COSAN] cobaltabis(dicarbollide) are reported here for the first time.Methods: Hamsters bearing tumors were injected with Na[o-COSAN] (7.5 mg B/kg) and euthanized at different time-points after injection (30 min, 2, 3, 5, and 18 h post-administration) to evaluate boron uptake in different tissues/organs. Based on these results, tumor-bearing animals were treated with Na[10B-o-COSAN]/BNCT (7.5 mg B/kg b.w., 3 h), prescribing 5 Gy total in absorbed dose to the precancerous tissue surrounding tumors, i.e., the dose-limiting tissue.Results: Na[o-10COSAN] exhibited no toxicity. Although biodistribution studies employing Na[o-COSAN] have shown low absolute boron concentration in the tumor (approx. 11 ppm), Na[o-10COSAN]/BNCT induced a high and significant therapeutic effect on tumors versus the control group (cancerized, untreated animals). Moreover, only half of the animals exhibited severe mucositis in the precancerous dose-limiting tissue after BNCT, which resolved completely at 21 days after irradiation.Conclusions: Na[o-10COSAN] would be potentially useful to treat head and neck cancer with BNCT.

Design and development of nanoprobes radiolabelled with 99mTc for the diagnosis and monitoring of therapeutic interventions in oncology preclinical research Salgueiro, María Jimena; Portillo, Mariano Gastón; Tesán, Fiorella; Nicoud, Melisa Beatriz; Medina, Vanina Araceli; Moretton, Marcela Analía; Chiappetta, Diego Andrés; Zubillaga, Marcela Beatriz Background: Previous studies employing polymeric micelles and molecular imaging for in vivo nanosystem characterization have led to the development of radionanoprobes (RNPs) designed for diagnosing and monitoring therapeutic interventions in preclinical oncology research, specifically within breast and colon cancer models. These models exhibit high GLUT1 expression on tumor cells and VEGFR expression on the tumor vasculature. We aimed to enhance the tumor-targeting specificity of these RNPs by functionalizing micelles with glucose and bevacizumab. The choice of 99mTc to label the nanoprobes is based on its availability and that direct labeling method is a widespread strategy to prepare radiopharmaceuticals using cold reagents and a 99Mo/99mTc generator. Soluplus® is an attractive polymer for synthesizing micelles that also allows their functionalization. With all the above, the objective of this work was to design, develop and characterize nanoprobes based on polymeric micelles and radiolabeled with 99mTc for the characterization of biological processes associated to the diagnosis, prognosis and monitoring of animal models of breast and colon cancer in preclinical research using molecular images.Results: Four RNPs (99mTcTc-Soluplus®, 99mTcTc-Soluplus®+TPGS, 99mTcTc-Soluplus®+glucose and 99mTcTc-Soluplus®+bevacizumab) were produced with high radiochemical purity (>95% in all cases) and stability in murine serum for up to 3 hours. The RNPs maintained the 100 nm size of the Soluplus® polymeric micelles even when they were functionalized and labeled with 99mTc. The image acquisition protocol enabled the visualization of tumor uptake in two cancer experimental models using the assigned RNPs. In vivo biological characterization showed signal-to-background ratios of 1.7 ± 0.03 for [99mTc]Tc-Soluplus®+TPGS, 1.8 ± 0.02 for [99mTc]Tc-Soluplus®, and 2.3 ± 0.02 for [99mTc]Tc-Soluplus®+glucose in the breast cancer model, and 1.8 ± 0.04 for [99mTc]Tc-Soluplus® and 3.7 ± 0.07 for [99mTc]Tc-Soluplus®+bevacizumab in the colon cancer model. Ex vivo biodistribution, showed that the uptake of the tumors, regardless of the model, is <2% IA/g while the blood activity concentration is higher, suggesting that the enhanced permeability and retention effect (EPR) would be one of the mechanisms involved in imaging tumors in addition to the active targeting of RNPs.Conclusions: Soluplus®-based polymeric micelles provide a promising nanotechnological platform for the development of RNPs. The functionalization with glucose and bevacizumab enhances tumor specificity enabling effective imaging and monitoring of cancer in animal models.

Spatial and temporal composition of herbaceous vegetation in Geoffroea decorticans (Gill. Ex Hook. & Arn.) Burkart. thickets Rauber, Ruth Bibiana; Arroyo, D.; Cendoya, Maria Alicia In the Central Semiarid Region of Argentina, the native woody species Geoffroea decorticans has increased in range and density, probably due to overgrazing. The aim of this work was to evaluate the floristic and functional composition of the herbaceous vegetation along time in grazed sites, within thickets of G. decorticans, and compared to grasslands. We registered the cover of each herbaceous species in different locations within thickets and in the natural grassland, at each season for two years, from autumn 2021 to summer 2023. Indicator species of grasslands were found to be mostly palatable native perennials, resulting more homogeneous than those of thickets. Moreover, the mean cover of palatable species was higher in grasslands than in thickets. Consequently, grasslands confer stability and food resource for livestock. Woody thickets would exhibit a decreased stratification from the center to the edge, that would give rise to niche opportunities and biodiversity reservoirs. Temporal variability in floristic composition indicated differences between grasslands and thickets over time, which decreased in spring, probably by homogenization by grazing in winter. The temporal variability of functional composition showed a cyclical variability in all locations that decreased in spring in all cases.

From livestock farming to amateur Botany in the Rio de la Plata: the case of the uruguayan Mariano B. Berro (1838–1919) García, Susana Valeria This paper focuses on the formation of an herbarium and the botanical exchanges conducted by a Uruguayan landowner, Mariano B. Berro (1838–1919), by analysing his archive deposited in the National Archives of Uruguay, which has been neglected as a source for the history of science. This case illustrates the relationship between animal husbandry and the observation and collection of local vegetation, especially the identification of forage plants. In particular, this paper analyses the correspondence between Berro and the Swiss pharmacist and landowner Teodoro Stuckert (1852–1932), who settled in the province of Córdoba, Argentina. Both of them began to assemble botanical collections in the 1890s, and maintained an intense correspondence for nearly 20 years, which provides insights into the practices of a vocational botanist from a rural area in the Rio de la Plata and the role of the network created to exchange specimens, data, and publications within South America as well as with Europe.

Participación del protofeminismo en el proyecto de Estado-nación : Una hipótesis teórico-política (1852-1878); Protofeminism’s Participation in the National State Project: A Theoretical-Political Hypothesis (1852-1878) Losiggio, Daniela El presente artículo se propone analizar la participación que tuvo el pensamiento protofeminista de periodistas, maestras y escritoras del siglo XIX argentino en el proyecto de Estado-nación. Partimos de la hipótesis de que Educación popular (1849) de Domingo Faustino Sarmiento constituye un texto fundante de la formación del Estado-nación argentino y que, tanto el libro como la implementación de su programa, se encontraban en diálogo con estas producciones de mujeres.; This article maintains that the proto-feminist thought of journalists and educators of the Argentine XIX century had a relative participation in the founding of the NationState; more specifically, in the popular education project of Sarmiento. To achieve that goal, we rely on women’s history studies. They allow us to shed new light on the canonical interpretations that, within political theory, reflect on the origin of the Argentine State.

Distritos económicos y renovación urbana en el sur de la ciudad de Buenos Aires; Economic Districts and Urban Renewal in the south of Buenos Aires city Arqueros Mejica, Maria Soledad; Goicoechea, María Eugenia; Vazquez, Diego Ezequiel; Fassina, Rosario Este artículo indaga en las transformaciones producidas en el entorno de los distritos económicos del sur de la ciudad de Buenos Aires, Argentina, (2008-2019) en el marco de las estrategias de renovación urbana y la propia trayectoria del territorio. Para ello se relevaron 780 lotes y distintas fuentes documentales (normativas, proyectos y programas). Los resultados de la investigación dan cuenta de fuertes diferencias vinculadas a la trayectoria del proceso de urbanización, las intervenciones públicas y las inversiones en el espacio, poniendo de relieve los diversos efectos de la política en el territorio.; This paper focuses on the urban changes in the surroundings of economic districts in the south of the city of Buenos Aires, Argentina, (2008-2019), within the framework of urban renewal strategies and the territory’s trajectory. For this purpose, we surveyed 780 lots and different documentary sources (regulations, projects and programs). The results of the analysis show strong differences linked to the trajectory of the urbanization process, public policies and investments in space, highlighting the various effects of politics in the territory.

Fiberwise criteria for twisted forms of algebraic structures Gille, P.; Pianzola, Arturo We provide a criterion for certain algebraic objects overJacobson schemes to be forms of each other based on theirbehaviour at closed fibres. This criterion permits to answer aquestion related to current and affine Kac-Moody Lie algebrasthat I. Burban had asked the authors.

Supplementary material for: Escherichia coli biogenic synthesized iron oxide nanoparticles: characterization, microbicidal and keratinocyte cellular effects Excel file containing data from experimental assays. Data from the assays are included: MTT, neutral red, crystal violet, production of reactive species (by NBT and DCFDA), wound healing, activity of the enzymes SOD, CAT and GST, and GSH content.

Temperature: Evaluation of Aedes aegypti winter survival in temperate Argentina The data correspond to average daily weather station temperatures and air and water temperatures measured with Hobo® dataloggers during August and September 2022.

Cuestionario Mind-Wandering: Adaptación Argentina Base de datos de la adaptación del Cuestionario Mind Wandering, diseñada para evaluar dispersión mental en población adulta argentina. La base de datos contiene variables sociodemográficas y las respuestas de los participantes al cuestionario. El cuestionario original fue adaptado para ajustarse a las características culturales, lingüísticas y contextuales de la población objetivo, garantizando su validez y fiabilidad en el nuevo entorno.

Longevity of Aedes aegypti during winter in temperate Argentina The data correspond to the longevity of females and males of Aedes aegypti from cohorts initiated in late autumn, early winter and mid-winter and under two treatments, sun and shade. The experiment was conducted under natural thermal and nutritional conditions representative of the temperate region of Argentina.

La vida afectiva en el arte independiente: Territorio sensible en la danza contemporánea del interior provinciano; Affective life in independent art: Sensitive territory in contemporary dance of the provincial interior Bertea, Francisco Miguel Fernando En este trabajo indagamos la vida afectiva en el arte independiente, específicamente en el mundo de la danza contemporánea del Valle de Paravachasca (Córdoba, Argentina), a partir de un trabajo etnográfico colaborativo de participación observante en el grupo Cantorodado, entre los años 2018-2022. Situados en los estudios sociales del arte y el giro afectivo, describimos de forma densa el territorio sensible de este mundo del arte, distinguiendo algunos de los vectores que lo componen, en calidad de tipos reales: una forma de (ganarse la) vida colectiva, una ética del cuidado y una atmósfera afectiva de entusiasmo. Empleamos para ello una propuesta analítica que se mueve en la tensión entre analítica-individuo y analítica-fuerza, entre las libertades relativas de los agentes y las estructuras estructurantes de sujeción. Realizamos así aportes a la comprensión de la vida afectiva de la danza contemporánea independiente y al arte independiente como forma de (ganarse la) vida, desde temáticas específicas, como la moral, la amistad, el management, el wellness y el don, reconociendo que la propuesta analítica empleada puede significar un aporte al estudio de la vida afectiva.; In this paper we investigate the affective life in independent art, specifically in the contemporary dance world of the Paravachasca Valley (Córdoba, Argentina), from a collaborative ethnographic work of observant participation in the Cantorodado group, between the years 2018-2022. Situated in the Social Studies of Art and the affective turn, we make a thick description of the sensitive territory of this art world, distinguishing some of the vectors that compose it, as real types: a way of (earning the) collective life, an ethic of care and an affective atmosphere of enthusiasm. We use an analytical proposal that moves in the tension between analytic-individual and analytic-force, between the relative freedoms of the agents and the structuring structures of subjection. We contribute at the understanding of the affective life of independent contemporary dance and independent art as a way of (earning a) living, from specific aspects linked: morality, friendship, management, wellness and gift. Acknowledging that the analytical proposal used can mean a contribution to the study of the affective life.

Use of cannabidiol-dominant extract as co-adjuvant therapy for type 2 diabetes mellitus treatment in feline: case report Massabo, José Ignacio; Puiatti, Gabriela; Ferrero, Paola Viviana Introduction: Diabetes mellitus (DM) is a common endocrinopathy in felines. Treatment is based on glycemic control and management of clinical signs by insulin administration coupled with a low-carbohydrate and high-protein content diet. However, achieving adequate remission or glycemia control is not always possible. Effects of cannabinoids on the regulation of glucose uptake and the incidence of diabetes have been observed in experimental models. Nevertheless, little is known about their possible relevance in controlling this condition in veterinary and human medicine. Case presentation: This is a case study of an 18-year-old, neutered, mixed-breed female domestic longhair cat diagnosed with type 2 diabetes mellitus. She was treated with long-acting glargine (3 to 5 IU/12 hs), and her diet changed to ultra-processed commercial food for diabetic cats. Three months after the start of the treatment with insulin, Cannabidiol (CBD)-enriched extract in handmade olive oil, THC: CBD ratio = 1:24, was incorporated. The route of administration was oromucosal. After three months, the glycemia was reduced. The patient decreased the polyuria/polydipsia, recovered sleep cycles, remained attentive to all movements, and increased her physical activity. Conclusion: This report provides evidence that using a CBD-rich extract was effective as a co-adjuvant in alleviating clinical signs of DM and concurrent disorders, allowing for the reduction of insulin intake.

Revisiting the massive star-forming complex RCW 122: New millimeter and submillimeter study Duronea, Nicolas Urbano; Bronfman, L.; Ortega, Martin Eduardo; Suad, Laura Andrea; Baume, Gustavo Luis; Mendoza, E.; Carvajal, M.; Cichowolski, Silvina; Arnal, Edmundo Marcelo; Finger, R.; Merello, M.; Gamen, Roberto Claudio In this paper, we present a new multifrequency study of the giant star-forming complex RCW 122. We used molecular data obtained with the ASTE 10 m and the APEX 12 m telescopes, along with infrared observations spanning from 3.6 µm to 870 µm, obtained from available databases. We also incorporated a range of public datasets, including the radio continuum at 3 GHz, narrowband Ha images, and deep JHK photometry. Our analysis focuses mostly on cataloged ATLASGAL sources, showcasing a spectrum of evolutionary stages from infrared dark cloud (IRDC)/high-mass protostellar object (HMPO) to ultra-compact HII region (UCHII), as inferred from preliminary inspections of the public dataset. Based on ASTE HCO+(4‑3) and CO(3‑2) data, we identified five molecular clumps, designated A, B, C, D, and E, as molecular counterparts of the ATLASGAL sources. These clumps have radial velocities ranging from ~‑15 km s‑1 to ‑10 km s‑1, confirming their association with RCW 122. In addition, we report the detection of 20 transitions from 11 distinct molecules in the APEX spectra in the frequency ranges from 258.38 GHz to 262.38 GHz, 228.538 GHz to 232.538 GHz, and 218.3 GHz to 222.3 GHz, unveiling a diverse chemical complexity among the clumps. Utilizing CO(2‑1) and C18O(2‑1) data taken from the observations with the APEX telescope, we estimated the total LTE molecular mass, ranging from 200 M⊙ (clump A) to 4400 M⊙ (clump B). Our mid- to far-infrared (MIR-FIR) flux density analysis yielded minimum dust temperatures of 23.7 K (clump A) to maximum temperatures of 33.9 K (clump B), indicating varying degrees of internal heating among the clumps. The bolometric luminosities span 1.7×103 L⊙ (clump A) to 2.4×105 L⊙ (clump B), while the total (dust+gas) mass ranges from 350 M⊙ (clump A) to 3800 M⊙ (clump B). Our analysis of the molecular line richness, L/M ratios, and CH3CCH and dust temperatures reveals an evolutionary sequence of A/E→C→D/B, consistent with preliminary inferences of the ATLASGAL sources. In this context, clumps A and E exhibit early stages of collapse, with clump A likely in an early HMPO phase, which is supported by identifying a candidate molecular outflow. Clump E appears to be in an intermediate stage between IRDC and HMPO. Clumps D and B show evidence of being in the UCHII phase, with clump B likely more advanced. Clump C likely represents an intermediate stage between HMPO and HMC. Our findings suggest clump B is undergoing ionization and heating by multiple stellar and protostellar members of the stellar cluster DBS 119. Meanwhile, other cluster members may be responsible for ionizing other regions of RCW 122 that have evolved into fully developed HII regions, beyond the molecular dissociation stage.

Flexible and configurable embedded electrical energy measurement system to acquire and process high-frequency features Véliz, Maximiliano Ezequiel; Real, Gustavo Ernesto; Otero, Alejandro Daniel A novel High-Frequency Electric Energy Metering System to inspect non-conventional features that may be relevant for studying real-time energy disaggregation and control of household appliances is presented. Integration of a data acquisition and control board, designed and built to be assembled with an Arduino Due, with the M90E36A Demo Board, allows for flexible and configurable electrical energy measurements. A key feature is that up to 4 current channels can be measured synchronously. On the one hand, samples can be obtained and processed by the M90E36A IC internal Digital Signal Processor at 3 Hz in the time domain and 2 Hz in the frequency domain. On the other hand, the M90E36A IC direct access memory mode can be operated, allowing 8 kHz pure voltage and current signals to be obtained. Finally, integration with Raspberry Pi allows to design and incorporate a custom signal processor into the study. Additionally, in this article, an application example is presented where the variation of the residual harmonic components of a household appliance is obtained.

Characterising cricket flour from Gryllus assimilis : an alternative source of nutrients for sustainability Toribio, Ezequiel; Correa, María Jimena; Medici, Sandra Karina; Ferrero, Cristina; Arp, Carlos Gabriel A trend to study entomological options as food is turning the practice of entomophagy into a novelresearch field in search for sustainable and accessible sources of nutrients. In this work, cricket (Gryllus assimilis) was processed into flour (CF), and then extracted using different solvents to obtain oils and defatted flours. The repeatability of CF obtention, its nutritional profile, and some of its physicochemical properties were studied. Results showed repeatability with a 28% mass yield for CF production. The CF presented adequate amino acid, mineral, and fatty acid profiles, a high content of dietary fibre, and low available carbohydrates, thus being considered a suitable alternative for inclusion in healthy human diets. Using data obtained from the total nitrogen content, the amino acid profile, and the total dietary fibre determinations, the CF protein digestibility was estimated at 67.4%. Based on experimental data, a mean nitrogen-to-protein conversion factor of 5.76 was calculated for a G. assimilis meal. The study showed that nutritional cricket flour and derivatives can be obtained using non-sophisticated methods.

A Decade of Monitoring Primary Healthcare Experiences through the Lens of Inequality Pasarín, M. Isabel; Rodríguez Sanz, Maica; Berra, Silvina del Valle; Borrell, Carme; Rocha, Kátia B. Background: Health care is not exempt from harboring social inequalities, including in those countries with a universal public system. The objective was to ascertain whether the population’s assessment of primary care (PC) changed between 2006 and 2016, the decade that included the economic crisis of 2008, and also if it exhibited patterns of social inequality in Barcelona (Spain). Methods: This was a cross-sectional study using Barcelona Health Surveys 2006 and 2016. Samples (4027 and 3082 respectively) comprised residents in Barcelona, over 15 years old. Dependent variable: Primary Care (PC) index. Independent variables: age, social class, and birthplace. Analyses included means and percentiles of PC index, and Somers’ D test to compare the distribution of the groups. Results: Comparing 2016 with 2006, the distribution of the PC index remained in women (median of 73.3) and improved in men (from 70 to 73.3). By social class, the pattern of inequality observed in 2006 in men with perceived poor health status disappeared in 2016. Inequalities according to birthplace persisted in women, regardless of perceived health status, but disappeared in men. Conclusions: In the 10 years between which the global economic crisis occurred, the assessment of PC did not worsen, and it did improve for men, but the study points to the need for more focus on people born abroad.

Planificar a partir del aprendizaje colaborativo en la formación inicial de profesores de Geografía; Planning from Collaborative Learning in the Initial Training of Geography Teachers Prieto, Maria Natalia; Volonté, Antonela; Maradona, Guillermina; Lorda, María Amalia El aprendizaje colaborativo es una estrategia activa que fomenta la participación directa de los estudiantes en la búsqueda de alternativas de solución a las contradic- ciones generadas en el proceso de aprendizaje; esta dinámica de trabajo favorece el aprendizaje significativo, las relaciones interpersonales (sociales), la comunicación, el aprendizaje autónomo, el desarrollo de habilidades de investigación y el fomento de valores humanos. La asignatura Didáctica y Práctica de la Geografía se dicta en el último año del profesorado en Geografía (Universidad Nacional del Sur, Argentina) y uno de los puntos centrales del proceso de enseñanza y aprendizaje es la forma- ción en la práctica docente reflexiva y supone una preparación fundamental antes del ingreso al ámbito escolar (práctica docente en la escuela secundaria). En esta instancia de preparación, se emplean diferentes dispositivos de formación, siendo uno de ellos el aprendizaje colaborativo. El objetivo de este trabajo es socializar una experiencia de organización de la enseñanza a partir del aprendizaje colaborativo. En ésta, los estudiantes del profesorado planifican propuestas de aula (en el contexto de una microclase) con un tema geográfico escolar. La experiencia, desde la consi- deración de los testimonios de los estudiantes, resultó innovadora ya que ayudó a fortalecer las habilidades sociales interactivas, la capacidad de autoevaluación, el pensamiento creativo, crítico, analítico y reflexivo. Asimismo, por implicar la gestión compartida de las decisiones didácticas, desde la dimensión cognitiva y socio-afectiva del aprendizaje, resultó una práctica valorada por su aporte al fortalecimiento del aprender a pensar “con el otro”.; Collaborative learning is an active strategy that encourages the direct participation of students in the search for alternative solutions to the contradictions generated in the learning process; This work dynamic favors meaningful learning, interpersonal (social) relationships, communication, autonomous learning, the development of research skills and the promotion of human values. The Didactics and Practice of Geography subject is taught in the last year of teaching in Geography (Universidad Nacional del Sur, Argentina) and one of the central points of the teaching and learning process is training in reflective teaching practice and involves preparation fundamental before entering the school environment (teaching practice in secondary school). In this instance of preparation, different training devices are used, one of them being collaborative learning. The aim of this paper is to socialize an experience of orga- nizing teaching based on collaborative learning. In this, the teaching students plan classroom proposals (in the context of a microclass) with a school geographic theme. The experience, from the consideration of the students’ testimonies, was innovative since it helped strengthen interactive social skills, the capacity for self-assessment, and creative, critical, analytical and reflective thinking. Likewise, because it involves the shared management of didactic decisions, from the cognitive and socio-affective dimension of learning, it was a practice valued for its contribution to strengthening learning to think “with the other.

Detrás del origen de arroz colorado en Argentina Presotto, Alejandro Daniel; Hernández, Fernando; Vercellino, Román Boris; Kruger, Raúl Daniel; Fontana, María Laura; Ureta, Maria Soledad; Crepy, Maria Andrea; Auge, Gabriela; Caicedo, Ana Las malezas agrícolas -que compiten fuertemente con los cultivos- son responsables de las mayores pérdidas de productividad de los cultivos (34%), seguidas por las algas y patógenos (con pérdidas del 18 y 16%, respectivamente) (Oerke, 2006).

“Picking up signals” in male genital morphospace and integrating phylogenomics to delimit Neotropical Nylanderia Emery species (Hymenoptera: Formicidae) Williams, Jason L.; Punnath, Aswaj; Fernández, María Belén; Calcaterra, Luis Alberto; LaPolla, John S.; Lucky, Andrea Genital morphology, a cornerstone in taxonomy that predates Linnaeus’s Systema Naturae, is vital for species delimitation. However, the widely accepted paradigm that genitalia are taxonomically informative lacks robust testing between closely related species, and supporting evidence is often limited to taxonomic literature in which genitalia are assumed a priori to be species-specific. The cosmopolitan ant genus Nylanderia Emery includes 123 described species, with most in the Neotropics still undescribed. Workers are often morphologically cryptic, and males are rare in collections but required for morphological delimitation. Using Ultraconserved Elements (UCEs) from 236 samples, including 53 Neotropical Nylanderia species, we reconstructed a phylogeneticframework to compare the genitalia (gonopods) of males collected alongside workers. We used geometric morphometrics on images of slide-mounted genitalia from 16 species and nano-CT scans of Nylanderia fulva (Mayr) and Nylanderia pubens (Forel) genital capsules and interpreted results considering phylogeny under maximum likelihood and the multispecies coalescent. We found strong morphological and molecular support for 2 distantly related American clades, identifiable by gonopod shape, with significant differences observed among most species. Three previously reported COI clades of N. fulva were not supported as monophyletic, nor were their gonopods significantly different. However, N. pubens was supported as distinct by allphylogenetic and 3DGM results. Our findings emphasize the importance of male genitalia for delimiting species boundaries and revising Neotropical Nylanderia. Given their importance, particularly in morphologically cryptic taxa, we recommend a greater focus on linking male and worker phenotypes, which can be facilitated through comprehensive nest series collection.