Revista del Museo Argentino de Ciencias Naturales
La Revista del Museo Argentino de Ciencias Naturales (RevMACN) está abierta a la comunidad científica nacional e internacional para la publicación de trabajos originales inéditos en Ciencias Naturales en las áreas de Botánica, Zoología, Paleontología, Ecología y Geología. La RevMACN publica trabajos en español e inglés. Al cumplirse más de 160 años de la aparición de la primera publicación científica argentina por el Museo Argentino de Ciencias Naturales (MACN), la revista continúa en forma ininterrumpida difundiendo sus artículos en forma libre para toda la comunidad. Forma parte del Núcleo Básico de Publicaciones Científicas Argentinas y por lo tanto es incluida en la biblioteca electrónica Scientific Electronic Library Online (Scielo). De acuerdo al índice SCImago Journal & Country Rank (SJR) que se basa en los contenidos de la base de datos de Scopus, se encuentra entre las primeras de las revistas científicas argentinas de ciencias naturales. Proporciona acceso libre a la comunidad científica de sus artículos que son publicados sin costo para los autores.
Los autores/as que publiquen en esta revista aceptan las siguientes condiciones: Los autores/as conservan los derechos de autor y ceden a la revista el derecho de la primera publicación, con el trabajo registrado con la licencia de atribución de Creative Commons, que permite a terceros utilizar lo publicado siempre que mencionen la autoría del trabajo y a la primera publicación en esta revista. Se permite y recomienda a los autores/as a publicar su trabajo en Internet (por ejemplo en páginas institucionales o personales), ya que puede conducir a a una mayor y más rápida difusión del trabajo publicado.
Derechos de autor 2025 Revista del Museo Argentino de Ciencias Naturales, nueva serie
Parasitology aiding fish taxonomy: Hyphessobrycon nicolasi as a jr. synonym of H. meridionalis (Characiformes:Acestrorhamphidae)
This study provides strong evidence in favor of considering Hyphessobrycon nicolasi as a junior synon- ym of Hyphessobrycon meridionalis. The analysis of the type material of H. nicolasi shows that the main diagnostic character between those species, which was based on supposed differences in coloration patterns due to the presence of an oblique black stripe along the margin of the caudal fin lobes in H. nicolasi, was in fact caused by metacercarial infection in some of the type specimens of H. nicolasi. Additionally, further examination of the types and other comparative materials did not reveal any other consistent phenotypic differentiation between these two taxa. Therefore, we consider Hyphessobrycon nicolasi as a junior synonym of Hyphessobrycon meridionalis. This finding highlights the importance of carefully considering the presence of parasites while describing new species of fishes as they can cause color changes or morphological alterations in their hosts.
Derechos de autor 2025 Revista del Museo Argentino de Ciencias Naturales
Guía y propuesta de mejora de la implementación del Protocolo de Nagoya en la investigación genética sin fines de lucro en Argentina
El acceso a la información genética en Argentina está regulado por la Resolución No. 410/19 de la Subsecretaría de Gobierno de Ambiente y Desarrollo Sostenible de la Nación. Esta regulación implementa el Protocolo de Nagoya (PN), que es un instrumento legal con el objetivo de asegurar el reparto equitativo de beneficios producidos por el uso de recursos genéticos, contribuyendo a la conservación y uso sustentable de los recursos biológicos. Los estudios genéticos sin fines comerciales conllevan múltiples beneficios para la sociedad. A pesar de ello, dichos estudios se ven afectados negativamente por el modo en el que el PN ha sido implementado en nuestro país. Por ende, consideramos que dicha implementación es susceptible de mejoras. Presentamos una guía para realizar investigación genética con fines puramente académicos en Argentina de acuerdo a la Res. No. 410/19, y proponemos medidas para mejorar y agilizar la implementación del PN. Específicamente, proponemos: 1) excluir a la investigación en organismos silvestres y sin fines de lucro de este régimen; 2) de ser necesario un Certificado de Cumplimiento, simplificar los trámites para obtenerlo, prescindiendo de avales y sin que se interprete que alcanzar el objetivo científico tiene un vencimiento temporal; 3) considerar a todos los Permisos de Colecta/Investigación como permisos de acceso; y 4) para proyectos que devinieron en actividades con fines de lucro, o para los casos donde se deba negociar beneficios no económicos, establecer un sistema prefijado de distribución de los beneficios del uso de los recursos genéticos común a todas las jurisdicciones.
Descripción del último estadio larval y de la pupa de Oedopeza ocellata (Coleoptera: Cerambycidae: Lamiinae)
Se describen e ilustran el último estadio larval y la pupa de Oedopeza ocellata (Fabricius, 1802) (Coleoptera: Cerambycidae: Lamiinae: Acanthocinini), a partir de ejemplares recolectados en la provincia del Chaco (noreste de Argentina). Se proporciona, además, una clave pictórica para identificar específicamente las larvas de las especies de Oedopeza descritas hasta la fecha.
Ciclo reproductivo y longitud de madurez de la barracuda mexicana Sphyraena ensis (Perciformes, Sphyraenidae) frente ala costa sureste del Golfo de California
Conocer las estrategias reproductivas de cualquier organismo permite implementar un manejo pesquero sostenible. La barracuda mexicana Sphyraena ensis es un recurso pesquero importante en el sureste del Golfo de California, el cual es aprovechado durante todo el año y sin regulación o restricción alguna. De acuerdo con los pescadores, los volúmenes de captura son menores y las tallas de los organismos más pequeñas, lo que puede deberse a una presión pesquera. El objetivo del presente estudio fue determinar el ciclo reproductivo y madurez sexual de la barracuda mexicana del sureste del Golfo de California. Las barracudas se obtuvieron de la pesca comercial en la costa de Nayarit, durante el periodo de febrero 2014 a enero de 2015. Se describió el desarrollo gonádico, la madurez sexual y el ciclo reproductivo de Sphyraena ensis, mediante histología. Además, se determinó la relación entre el evento reproductivo y los factores ambientales. Los testículos presentan conductos seminíferos dispuestos longitudinalmente y los ovarios tienen un arreglo concéntrico de las laminillas ovígeras. El desarrollo gonádico es asincrónico, se pueden observar desoves y espermiación por un largo periodo de tiempo. El periodo de reproducción es extenso, prácticamente durante todo el año. Sin embargo, el periodo con mayor actividad de desove y espermiación (marzo a junio) está influenciado por la cantidad de horas luz y la concentración de clorofila-a. La talla media de madurez sexual fue de 38.4 y 36.2 cm de longitud total para hembras y machos, respectivamente.
New species of the highly diversified Hoplias malabaricus group (Characiformes, Erythrinidae) from La Plata Basin: Another brick in the wall
With 13 species, the genus Hoplias contains more than 75% of the diversity of the family Erythrinidae. However, cytogenetic and molecular studies strongly suggest the existence of an outstanding cryptic diversity in this genus, with more than 20 likely new species only for the H. malabaricus group. Here, we described a new species for this group, including specimens from a wide geographic coverage within La Plata Basin: Iguazu River and Urugua-í Reservoir in Argentina and upper Parana River in Brazil. Traditional taxonomic and molecular analyses were performed. The new species is diagnosed by the following combination of characters: 15–17 predorsal scales, 38–41 lateral-line scales, 10–11 premaxillary teeth; 8–10 plate-like denticulate rakers in ceratobranchial, 39–41 vertebrae, pectoral-fin length (16.24–19.58 % SL), orbital diameter (13.15–20.06 % HL), the last vertical scale row in the caudal fin forming a straight line and the last portion of the ascending process of the premaxilla with a marked ridge. A key for the species of the H. malabaricus group is provided. This work contributes to the inventory of biological diversity of the study region but also aims to accurately identify species belonging to a group with complex taxonomy.
Hermaphroditism and preliminary reproductive study ofHermaphroditism and preliminary reproductive study of the sea-urchin, Pseudechinus magellanicus, in the Beagle Channel (Tierra del Fuego, Argentina)
The sea urchin Pseudechinus magellanicus, abundant in the Beagle Channel, plays a crucial role in the benthic ecosystem. This study presents the first documented records of hermaphrodites of P. magellanicus in the Beagle Channel and provides updated insights into its reproductive dynamics in the studied population. Monthly samplings (30 adult individuals each) were conducted between July and September 2023, assessing sex and reproductive stage through histological analysis. A total of 90 individuals were examined, 45 identified as male, 39 as female, and 6 as hermaphrodites. Excluding hermaphrodites, the sex ratio was 1:1, and the hermaphroditism incidence was 6.67%. The hermaphrodites were found in pre-mature II, mature, or partially spawned stages. Various types of hermaphrodites were identified, including three hermaphrodites with male predominantly characteristics, one with predominantly female characteristics, and two ovotestes. Hermaphrodite gonads were classified based on the presence and distribution of female and male germ cells within the same or different acini. While these findings provide valuable insights into the reproductive biology of P. magellanicus in the Beagle Channel, the underlying factors of the observed cases of hermaphroditism remain speculative and require further research to assess potential environmental influences and their implications.
Recurrent juvenile stranding of the porbeagle shark Lamna nasus along the South West Atlantic coast
Strandings of juvenile porbeagles are recurrent in the South West Atlantic (SWA). We provide new biological information and explore to which haplogroups the juveniles may belong. Fourteen stranding events occurred between May 2009 and May 2022 on porbeagle in the beaches of the SWA Argentine coast were identified. Based on a 2019 beached specimen, total length, 83 morphometric measures, and the parasites diversity were provided, as well as the COI gene sequences, derived from DNA extraction from muscle tissue, followed by PCR. The sequence matched Lamna nasus (98.76% – 100.00%; n=100), using the Barcode of Life Data System identification. Molecular data show a great genetic diversity in COI sequences, especially between northern and southern hemisphere samples, in accordance with previous studies. In addition, juveniles recorded in northern Argentine coastal waters differ in COI nucleotide sequences and are located in different clusters in the maximum likelihood (ML) analysis. The haplotype network built showed a star-shaped topology and, as the ML tree, revealed the existence of three genetically distinct clusters. A partition of the genetic variation into Southern Hemisphere and Northern Hemisphere groups was observed.
Evaluación de la contaminación por microplásticos en el liquen Candelaria concolor (Dicks) Arnold, 1879: un estudio de caso sobre el Efecto de la Ruralidad
Este estudio investigó el potencial del liquen C. concolor como bioindicador de la contaminación por microplásticos en relación con las áreas rurales. Se recolectaron muestras de liquen en sitios rurales, rururbanos y urbanos dentro del partido de Luján, Argentina. La extracción de microplásticos involucró un método modificado de oxidación húmeda con peróxido y tinción negativa utilizando ferroína. Se identificaron un total de 124 MP, todos ellos microfibras. El número de microfibras por gramo mostró una correlación negativa significativa con la ruralidad. A pesar de su menor presencia en las zonas rurales, C. concolor mostró una mayor capacidad de acumulación de MP que otras especies de líquenes estudiadas. Proponemos a C. concolor como un bioindicador prometedor para la contaminación por MP en entornos rurales, si bien reconocemos la necesidad de realizar más investigaciones para dilucidar los mecanismos subyacentes y explorar explicaciones alternativas para los patrones observados. Además, este estudio introduce un método rentable para la extracción de MP de líquenes, lo que facilita futuros estudios en entornos con recursos limitados. En general, este trabajo proporciona información valiosa sobre la contaminación por MP en áreas rurales y destaca el potencial de C. concolor como bioindicador en este contexto.
New fossiliferous locality from the Anacleto Formation (Late Cretaceous, Campanian) from northern Patagonia, with the description of a new titanosaur
Resumen. En la presente contribución se describe una nueva asociación de vertebrados e invertebrados fósiles provenientes de una localidad fosilífera previamente desconocida de la Formación Anacleto (Campaniano, Cretácico Superior), cerca de la ciudad de General Roca, provincia de Río Negro, Argentina. Los especímenes fueron recolectados en un mismo nivel estratigráfico incluyendo bivalvos y gasterópodos, entres estos últimos el primer registro fósil de la familia Neocyclotidae y el primer registro fósil de la familia Megalomastomatidae y el primer registro indudable del subulínido Leptinaria. Los vertebrados están representados por peces (lepisostéidos y el dipnoo Metaceratodus kaopen), tortugas quélidas, un pterosaurio indeterminado, una mandíbula de mamífero meridioléstido, una placa de un crocodyliformes y dinosaurios, incluyendo abelisáuridos indeterminados y un nuevo titanosaurio rinconsaúrido. Este último está representado por varios individuos pertenecientes a una forma de tamaño pequeño y miembros relativamente gráciles. El análisis filogenético recupera un Rinconsauria monofilético que incluye al nuevo taxón, así como Rinconsaurus, Pitekunsaurus, Overosaurus y Muyelensaurus. El nuevo titanosaurio indica que los rinconsáuridos formaban un clado caracterizado por una morfología corporal diferente a la de otros titanosaurios, con una postura del tipo braquiosaurio, miembros gráciles y cola con curvatura protónica. El conjunto faunístico se caracteriza por la abundancia, pero baja diversidad, de tortugas quélidas y un número muy reducido de crocodyliformes. Esta composición taxonómica recuerda a otras asociaciones faunísticas del Cretácico tardío del norte de la Patagonia, pero difiere notablemente de los conjuntos conocidos para el Campaniano de América del Norte y Europa.
Use of microhabitat features for egg capsule deposition by amarine limpet
Patagonian intertidal habitats are one of the world’s most extreme environments for marine organisms. These have different life-history strategies to reduce the stress that they are exposed to and survive within these habitats. In this study, we search for the presence of a common grazer along the different intertidal levels, then, identify areas used for egg capsule deposition, and investigate the microhabitat features associated with them. To achieve these goals, we described biotic and abiotic microhabitat characteristics, as well as their relationship with egg capsules. We found that individuals were present from the high intertidal level to the fringe area between the mid and low levels, but not beyond this point. Egg masses were only observed within this fringe level and were closely associated with sessile organisms present in that area, such as sponges, algae, and barnacles. We propose that limpet reproductive output may be enhanced by favourable microhabitats that are related to biotic features that would protect egg masses from desiccation and potential predation.
Returning the dragon to its cave: the spinosaurid nature of the purported ornithopod materials from the ‘Middle’ Cretaceous Alcântara Formation, northeastern Brazil
We have conducted a reassessment of dinosaur caudal vertebrae from the Cenomanian Alcântara Formation in the Maranhão State, northeastern Brazil. These elements were originally described as belonging to the coeval African theropod Sigilmassasaurus. Subsequently, they were reassigned to a large ornithopod similar to the slightly older Ouranosaurus, representing the first occurrence of a basal hadrosauriform in South America. Here we review the anatomy of the caudal vertebrae from the Alcântara Formation, emphasizing comparisons with both spinosaurid theropods and hadrosauriform ornithopods to re-evaluate their taxonomic assignment between these two distantly related groups. Characters such as centra with subrectangular lateral walls, ventral surface bearing a longitudinal depression, low base of the neural arches, rod-shaped neural spines and transverse processes not reaching the anterior and posterior borders of the centra, among others, allow referral of these vertebrae to Spinosaurinae. The only nominal spinosaurid described for the Alcântara Formation is Oxalaia quilombensis. However, the absence of overlapping material precluded the referral of the Maranhão caudal vertebrae to this species. Furthermore, the existence of multiple dental morphotypes in the Alcântara Formation that suggests a greater diversity of spinosaurids opens the possibility of those vertebrae belonging to a different species. Nevertheless, the reassignment of the Maranhão caudal vertebrae to Spinosauridae nullifies the evidence of ornithopod remains in the Alcântara Formation and limits its record in northeastern South America to footprints from Cenomanian strata.
Estimación de la longitud total y el peso de Helcogrammoides cunninghami (Perciformes, Tripterygiidae) de Playa Santa Isabel (Chubut, Argentina) a partir de otolitos, huesos craneales y de la cintura escapular
En el presente trabajo, se generaron regresiones para estimar el peso húmedo a partir de la longitud total, y el peso húmedo y la longitud total a partir de medidas de otolitos, huesos craneales y de la cintura escapular de Helcogrammoides cunninghami. No se encontraron diferencias en la relación peso húmedo-longitud total entre machos y hembras, observándose un crecimiento isométrico entre el peso húmedo y la longitud total. Las medidas de los huesos explicaron mejor que los otolitos los cambios en el peso y la longitud total de los ejemplares de H. cunninghami. Las ecuaciones obtenidas son una herramienta para la investigación en ecología trófica a fin de evaluar el rol de H. cunninghami en la dieta de depredadores piscívoros.
Pikelinia schiapelliae, una nueva especie de araña de arenales de Argentina y Uruguay (Araneae: Filistatidae)
El género Pikelinia es el principal representante de la familia de arañas Filistatidae en Sudamérica, con 19 especies nombradas. Sin embargo, mucha de su diversidad queda por ser descripta. En este manuscrito, damos a conocer a Pikelinia schiapelliae Magalhaes sp. nov. con base en ejemplares recolectados en áreas de vegetación chaqueña y suelo arenoso de las provincias de Buenos Aires, Santa Fe y Entre Ríos (Argentina) y de Río Negro (Uruguay). La nueva especie se distingue de sus congéneres por la morfología de las estructuras sexuales y por las secuencias de ADN del gen de la citocromo c oxidasa, subunidad I. A través de muestreos sistematizados en la Isla Martín García, pudimos observar que Pikelinia schiapelliae: (1) es más abundante en los meses que siguen el solsticio de verano; y (2) es más frecuentemente encontrada en áreas de suelo arenoso. Un análisis filogenético basado en cuatro marcadores moleculares indica que P. schiapelliae es cercana a otras especies que también habitan suelos arenosos, como Pikelinia arenicola, lo cual sugiere la existencia de un clado de Pikelinia especializado en vivir en estos tipos de ambientes. Pikelinia arenicola, previamente conocida únicamente para Brasil, se registra por primera vez para Argentina y Uruguay.
Colección de referencia de maderas carbonizadas de especies arbóreas del bosque en galería del Parque Nacional Pre- Delta, Entre Ríos, Argentina: su importancia en los estudios arqueobotánicos
El Parque Nacional Pre-Delta (PNPD) en Entre Ríos, Argentina, es una zona protegida que alberga una composición específica de especies vegetales. El objetivo de este trabajo es describir la anatomía del xilema secundario carbonizado de especies leñosas del bosque en galería del PNPD para que contribuyan en la identificación de plantas en el registro antracológico de contextos arqueológicos y naturales. Ramas de nueve especies leñosas del boque en galería del PNPD, con diámetros mayores a 2 cm y de aproximadamente 10-15 cm de largo, fueron carbonizadas en mufla de 400° C por 40 minutos para ser observadas bajo microscopio estereoscópico, microscopio trinocular invertido y microscopio electrónico de barrido. Se analizan los caracteres eco-anatómicos de las especies estudiadas. Finalmente, fueron ingresadas a la Colección de Material Carbonizado (CIDPALBO-CAR) del CICYTTP (CONICET-Gobierno de Entre Ríos-Universidad Autónoma de Entre Ríos). Los ejemplares estudiados, de acuerdo a sus tres planos de observación (transversal, longitudinal tangencial y longitudinal radial), son Croton urucurana Baill; Nectandra angustifolia (Schrad.) Nees & Mart.; Vachellia caven (Molina) Seigler & Ebinger; Tessaria integrifolia Ruiz & Pav.; Inga sp.; Pseudalbizzia inundata (Mart.) E. J. M. Koenen & Duno; Sapium haematospermum Müll. Arg.; Myrsine laetevirens (Mez) Arechav y Eugenia myrcianthes Nied. La descripción de las características anatómicas de la madera de las especies del bosque en galería del PNPD es esencial para identificar restos antracológicos en sitios arqueológicos y reconstruir patrones de uso del ambiente en el pasado. Esta contribución constituye el primer estudio anatómico de material carbonizado provenientes de la eco-región Delta e Islas del Paraná. Además, la inclusión de estas especies en la colección de referencia del Laboratorio de Paleobotánica del CICYTTP es un aporte significativo para la investigación arqueológica y paleontológica de la región.
Identificación y evaluación antagónica in vitro de cepas de Trichoderma spp. nativas contra patógenos del duraznero
El interés en el control biológico de fitopatógenos ha aumentado de manera considerable, debido a la necesidad de introducir alternativas eficaces amigables con el medio ambiente, y dejar a un lado el uso masivo de agroquímicos. Trichoderma es un agente antagónico utilizado como medio natural contra fitopatógenos. El objetivo de la presente investigación fue aislar e identificar morfológica y molecularmente cepas nativas de sp. del sur del estado de Chihuahua, México, probando su capacidad antagónica contra fitopatógenos. Se aislaron cuatro cepas de Trichoderma sp asociadas a plantas como Prunnus persica, Pinnus sylvestris y Arbutus unedo. En las pruebas de antagonismo in vitro se evaluaron las cepas 1, 3, 5 y 8 contra los fitopatógenos Fusarium sp., Alternaria sp., Epicoccum sp., Monilinia sp. y Collectotrichum sp. sometiendo los datos a la prueba ANOVA de Aligned Rank Transformation con 10 tratamientos y siete repeticiones más un testigo. La identificación morfológica de los antagonistas se llevó a cabo de acuerdo con las características de la cepa, crecimiento físico y desarrollo estructural de resistencia, secuenciado los genes EF1-728F (5′-CATCGAGAAGTTCGAGAAGG-3′) y TEF1LLErev (5′-AACTTGCAGGCAATGTGG-3′) y los cebadores ITS1 e ITS4 (ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) / ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) para identificar las especies presentes. Todas fueron identificadascomo Trichoderma asperelloides y presentaron un aceptable control sobre el control de fitopatógenos. La prueba post hoc detectó diferencias significativas en la cepa 1 presentando 81.2% de control biológico in vitro. Se sugiererealizar evaluaciones en planta de durazno a nivel campo.
The composition of fatty acids in female gametes of Arbacia dufresnii (Arbaciidae: arbacioida) in the population of Bahía Norte, Nuevo gulf indicates good nutritional conditions
Here we study the population of Arbacia dufresnii in two locations within Nuevo Gulf (Bahía Norte and Punta Cuevas), Argentina, focusing on their size, density, and nutritional status through fatty acid (FA) profiles. Sea urchins were collected by scuba diving, analysing 4000 individuals over an entire year. The results showed that sea urchins in Bahía Norte are larger but less dense than those in Punta Cuevas. Polyunsaturated fatty acids (PUFA) and highly unsaturated fatty acids (HUFA) were predominant in Bahía Norte, indicating a diet rich in high-quality nutrients. A. dufresnii showed an omnivorous diet with a tendency towards carnivory in Bahía Norte. Additionally, significant differences in trophic markers were found between both locations, suggesting variations in food availability and quality. A. dufresnii proved to be an excellent bioindicator, reflecting environmental and nutritional changes in its FA profiles.
A chronology of the genus Thylamys (Didelphidae, Thylamyini), with emphasis in the forms occurring in Argentina
The genus Thylamys includes several species of small mouse opossums living predominantly in arid and semi-arid regions of South America. In Argentina, where the genus has more species, different species have been recognized (T. bruchi, T. citellus, T. pallidior, T. pulchellus, T. sponsorius, and T. venustus), but their taxonomy is still confusing. Here, I summarize what we know of the systematics and taxonomy of Thylamys in Argentina, including the main sources of controversy between species. I also provide a differential diagnosis for the species I recognize, a chresonymy, and current distribution maps. Finally, I describe the main issues that should be addressed to improve our understanding of the genus in Argentina.
External malformations in the green sea urchin Arbacia dufresnii (Blainville, 1825) in populations from Golfo Nuevo, Patagonia, Argentina
Malformations in sea urchins can manifest in various forms, often influenced by environmental and biological factors. Adult Arbacia dufresnii (Blainville, 1825) exhibit pentaradial symmetry, spines in the ambulacral areas, absence of spines in the interambulacral areas, and a rhomboidal periproct composed of four ossicles. This report aims to document the presence of external malformations in the green sea urchin Arbacia dufresnii in the population of Golfo Nuevo, Patagonia, Argentina (42°42′ S 64°30′ W). A total of 319 specimens were collected, out of which 5 showed malformations. The malformation include: absence of pentaradial symmetry, spines in the interambulacral areas, and non-rhomboidal periprocts covered by three supraanal plates. These findings suggest the need for monitoring external malformations in populations of A. dufresnii and other Echinoidea, as they could provide crucial information abouth the health and status of these populations. Malformations may serve as biomarkers of environmental stress, pollution, or habitat condition changes, which is essential for effective conservation measures.
Development patterns and oxidative metabolismof antarctic sea stars
Sea stars exhibit different development patterns that comprise indirect and direct development, including pelagic or benthic larvae, and planktotrophic or lecithotrophic nutrition. The purpose of our research was to study the general parameters of oxidative metabolism during female gonadal maturation in Antarctic sea stars with different development patterns. Summer sampling was performed in 2012 in Antarctica. Every asteroid was taxonomically identified, and its development pattern was established. Sex and the reproductive stage were determined through histological analyses. The general parameters of the oxidative metabolism were determined in mature ovaries by measuring reactive oxygen species (ROS) and total antioxidant capacity (TAC). The development patterns with internal or oral brooding presented a lower production of ROS than those with a broadcaster strategy. The free-living planktotrophic larvae pattern presented lower TAC values than both types of brooding patterns. The development patterns of free-living lecithotrophic larvae and facultative lecithotrophic larvae presented intermediate values of TAC but did not show significant differences. We concluded that species that offspring rapidly acquire the ability to feed during development (planktotrophic larvae) exhibit lower TAC and higher levels of ROS than the species that do not feed during their development, which will receive greater maternal supply of antioxidants, resulting in reduced ROS levels. The development patterns with brooding ensure better quality oocytes and higher fitness in offspring than those unprotected.
Oral brooding (Anasterias antarctica) versus internal brooding (Diplopteraster verrucosus): Contrasting strategies of the brooded juveniles for full development
Both sea star species in this study are brooders from the South Atlantic. Anasterias antarctica displays a complex reproductive cycle involving incubation during eight or nine months and it broods its offspring over the mouth, while Diplopteraster verrucosus displays continuous reproduction and broods its offspring in nidamental chambers under the dermis. We collected A. antarctica in May, August, and November (beginning, mid and late incubation) from Parque Nacional Tierra del Fuego (Tierra del Fuego AeIAS, Argentina), while D. verrucosus was collected at three Oceanographic Research Cruises at Namuncurá Marine Protected Area/ Burdwood Bank I and II. We measured general parameters of oxidative metabolism (reactive oxygen species “ROS” and total antioxidant capacity “TAC”), energy density, and energy content in three different stages during offspring development. In the case of A. antarctica, energy depletion, increasing ROS and constant TAC levels at the late development stage could act as a developmental constraint and trigger the independence of juveniles. Similarly, in D. verrucosus juveniles, which exhibit extra embryonic maternal nutrition, despite the continued increase in energy, the antioxidants present in this kind of nutrition do not counteract the ROS generated by the metabolic rise.
Asteroidea (Echinodermata) from Uruguay (SW Atlantic): an annotated checklist and zoogeographic considerations
The diversity of Asteroidea from the Southwestern Atlantic between 30° S and 40° S (southern Brazil, Uruguay, and northern Argentinean waters) has been studied since the late 19thcentury. However, like many other benthic metazoans, the existing knowledge of species particularly reported from Uruguayan waters has remained dispersed and scarcely considered until now. This work aims to compile, analyze, and discuss all published records of sea stars from Uruguay. These correspond to 42 species for which detailed locations are available. Some of these localities were originally vague and are clarified here. Based on current knowledge, this asteroid fauna includes mostly tropical and subtropical as well as Antarctic and subantarctic shelf and deepwater species, with three deepwater endemisms standing out in the Argentine Basin (Psilaster herwigi, Dytaster grandis nobilis and Pythonaster murrayi). Future research should focus on analyzing the abundant unstudied material available in collections and developing deep-sea sampling and integrative taxonomy.
Seasonal population structure of the sea star Anasterias antarctica in intertidal boulders of the Protected Natural Area Puerto Lobos, Atlantic Patagonia
Intertidal boulders are complex marine environments which support unique marine assemblages, including species generally restricted to tide-pools, and also characteristics which make them ideal for experimental studies to further understanding ecological patterns. The goals of this study were to describe the seasonal population structure of the sea star Anasterias antarctica over two years and test the effects of environmental conditions over sea stars population in intertidal boulders of the Protected Natural Area Puerto Lobos in San Matías Gulf, Atlantic Patagonia. Our results showed seasonal differences in biomass and size of A. antarctica population over the two years sampled, although not significant relation was observed due to environmental conditions measured. To better understand A. antarctica population structure in the intertidal boulder fields of Puerto Lobos area more environmental variables need to be measured, as well as carrying out specific sampling to detect the smallest sizes of sea stars after the release of juveniles. These findings underscore the necessity of incorporating seasonal dynamics into monitoring programs for species that play key roles in communities, enabling us to detect potential changes driven by anthropogenic pressure or climate change, highlighting the importance of the study of these unique and poorly known rocky environments in Atlantic Patagonia.
A century of echinoderm research in Argentina: Irene Bernasconi’s lasting legacy from 1925, with notes on type material and publication chronology
Irene Bernasconi was a pioneering and internationally recognized echinoderm specialist from Argentina. Her career, which spanned nearly six decades, was marked by significant contributions to the taxonomy of echinoderms, particularly those from the southwestern Atlantic and Antarctic Peninsula. She laid the foundation for the inclusion of women in science in her country. Bernasconi contributed to the description of 25 new taxa (three subspecies, 21 species, one genus). She was based at the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (MACN), initially in an honorary role and later as a CONICET researcher. This review addresses the status of the species that she described, including nomenclatural updates. Also we compiled her extensive publication record of 68 research articles, highlighting her focus on asteroids (60% of her studies), echinoids (32%), and ophiuroids (26%), with minor contributions to crinoids and holothuroids (3% for both). The first publication by Bernasconi appeared in 1925, and her final work was completed in 1980, reflecting her valuable commitment to echinoderm studies as a cornerstone in the region.
Intertidal occurrence of the sea urchin Pseudechinus magellanicus (Temnopleuridae) along the coasts of Argentina and southern Chile
The study aimed to assess the coastal distribution of the widespread sea urchin Pseudechinus magellanicus along the southwestern Atlantic coast, focusing on its occurrence in the intertidal zone and explore its relationship with environmental factors. Data was collected in intertidal rocky shores across 36 sites along the Argentine and Chilean coasts during 2007 and 2010. The presence of P. magellanicus was verified in the intertidal zone on rocky coasts of Argentina between latitudes 45°S and 55°S, most frequently in the central area of the San Jorge Gulf, the Strait of Magellan, and the Beagle Channel. A fragmented coastal distribution is observed with the absence of the species in the intertidal zone between latitudes 47.2°S (Cape Blanco) and 54°S (Cape San Pablo). Logistic regression analysis and regression and classification trees (CART) suggest that higher water transparency and lower levels of dissolved chromatic organic matter in nearshore waters could explain its presence on intertidal platforms. Furthermore, in sites with high wave exposure, the likelihood of finding P. magellanicus increases rapidly only in sites with higher water transparency, while this increase is slower in sites with low transparency values. Establishing baseline data on the coastal distribution of these species is crucial for monitoring and evaluating the impacts of environmental shifts in the context of climate change and increasing human activity in coastal habitats.
Hidden biodiversity in the Southwestern Atlantic Ocean: brittle stars from the Mar 2 del Plata Submarine Canyon, Argentina
Among the phylum Echinodermata, the class Ophiuroidea is the most diverse, with brittle stars being widely distributed across benthic environments worldwide. However, this trend is not consistently observed in the Southwestern Atlantic, where other echinoderm classes are reported to be more prevalent. The apparent low biodiversity may be due to insufficient studies and sampling in the deep sea, particularly in small and localized environments like submarine canyons. These geomorphic features of the continental margins are known to support unique marine communities and high biodiversity, as shown by oceanographic expeditions to the Continental Shelf of Argentina on the research vessel Puerto Deseado (CONICET) over ten years ago. These explorations significantly expanded our knowledge of benthic fauna diversity in the Southwest Atlantic. Subsequent studies have reported new fauna records and species, revealing a complex and largely uncharacterized environment, especially regarding brittle stars, a topic still pending thorough study in this area. The present study aims to enhance our understanding of ophiuroid species richness in this deep-sea environment, providing essential data for generalization and biogeographic studies globally. The study area includes the Argentine Continental Slope and the Mar del Plata Submarine Canyon in the Southwestern Atlantic Ocean. We examined samples from 64 stations at depths ranging from 200 to 3,447 meters. Ophiuroids were found in 81% of the surveys, with approximately 6,000 specimens collected. The study area reveals a potential richness of 56 ophiuroid species, including 32 validly recognized species (16 new records for the Argentine Sea) and 24 unidentified or partially identified species. These data more than doubles the known ophiuroid species in the region, highlighting that deep-sea environments are key biodiversity hotspots and could contain significant biodiversity in the Southwestern Atlantic Ocean.
Ecological role of the sea urchin Austrocidaris canaliculata (Cidaroida: Cidaridae) as a basibiont: Epibiont assemblages in the Marine Protected Area Namuncurá – Burdwood Bank and adjacent deep areas
Organisms that provide settlement sites for sessile fauna play a key role in shaping the structure of benthic communities. Sea urchins of the order Cidaroida can offer these sites for settlement on their primary spines, which lack antifouling protection. In this study, the ecological role of Austrocidaris canaliculata (Cidaroida: Cidaridae) as a basibiont at the MPA Namuncurá – Burdwood Bank (MPA NBB) and adjacent deep-sea areas was evaluated. For this, we described the composition and the diversity of the epibiont assemblages within the MPA NBB and external deep-sea sites. Additionally, we analyzed the relationship between the size of A. canaliculata and the epibionts richness in these zones using generalized additive models. From the 120 specimens of A. canaliculata studied, epibiosis was recorded in 96.67%. A total of 39 epibiont taxa were identified, representing two kingdoms, 10 phyla, 13 classes, and 27 families, including new records of species in the study area. The highest epibiont species diversity observed was Bryozoa, followed by Cnidaria. The epibiont assemblages showed no significant differences in the estimated diversity within each zone, and the estimated epibiont richness was slightly higher in deep-sea areas. Finally, our modelling suggests that the epibiont richness is correlated with the horizontal diameter of the test, showing an opposite variation between shallow and deep-sea zones. This study provides detailed faunistic information on the epibionts associated with A. canaliculata from the MPA NBB and adjacent deep-sea areas, reinforcing the ecological role of cidaroids as basibionts in benthic ecosystems.
Biodiversity, bathymetric distribution, and reproductive strategies of sea stars (Echinodermata: Asteroidea) in the Argentine Sea
Sea stars (Echinodermata: Asteroidea) are widely distributed across all oceans, with numerous species inhabiting the Argentine Sea. This region is highly productive and sustains a rich diversity of marine invertebrates. The present work aimed to conduct a comprehensive bibliographic until 2024 review focusing on the biodiversity of Asteroidea in the different marine environments of Argentina and the reproductive strategies of sea stars inhabiting the Argentine Sea. This study focused on the geographic region from the Río de la Plata to the Burdwood Bank. We identified 105 species of sea stars, grouped into six orders, 19 families, and 60 genera. Valvatida and Forcipulatida were the most diverse orders. We noted a prevalence of sea stars in intermediate waters (50–500 m), being present across a wide range of temperatures. Regarding reproduction, our results showed that most of the brooding species were located exclusively in cold and intermediate waters, while broadcast spawner species exhibited a broad distribution from shallow to intermediate waters. This review highlights gaps in reproductive data for most species, as most studies in Argentina focus on identifying species from shallow rather than deeper waters. Enhancing sampling efforts and updating the biological information of these species will likely address these gaps in knowledge, especially in deeper areas where sampling is more challenging. Our results contribute to updating the knowledge of Asteroidea diversity in the Argentine Sea.
Diversity of genus Phromachocrinus Carpenter, 1879 of the National Invertebrates collection, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”
Professor Irene Bernasconi was a pioneer in Antarctic crinoid research in Argentina, with her work on Promachocrinus kerguelensis published in 1932. This study review Promachocrinus material housed in the collection of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (MACN-In), including specimens collected by Carcelles in 1929. Through an analysis of new samples from Antarctic expeditions and a review of historical material, three species within the genus were identified: P. kerguelensis, P. fragarius, and P. joubini. These studies update the understanding of genus diversity, previously considered a single circum-Antarctic species, and underscore the importance of integrating molecular and morphological methods for identifying cryptic species. This advancement emphasizes the need to reassess historical biodiversity records and highlights the significance of pioneering researchers such as Bernasconi.
Shallow species of Holothuroidea in the collection of the Museo Argentina de Ciencias Naturales “Bernardino Rivadavia” (MACN)
Echinoderms in Argentina are closely associated with the pioneering studies of Irene Bernasconi, particularly regarding sea cucumbers from the collection at the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (MACN). The Holothuroidea class comprises 325 lots from various global regions, as recorded in the MACN invertebrates collection (MACN-In). This study analyses all specimens from shallow waters of Argentina and includes detailed information on species distribution, depth range, and remarks for each species, along with a key for identification. We identified 19 out of 26 species known to inhabit Argentina, representing 73% of the recorded species. The absence of certain specimens may stem from challenges in sampling, restricted distributions, or past misidentifications in literature. This research enhances our understanding of Argentina’s biological diversity. Future studies aim to build on this foundation and continue the legacy initiated by Bernasconi.