Helminth Parasites of the Crane Hawk Geranospiza caerulescens (Vieillot) (Aves: Accipitridae) from Argentina, with the Description of a New Species of Parastrigea (Digenea: Strigeidae).

PURPOSE: The goal of this work was to increase the knowledge of the parasitic helminths of the Crane hawk, Geranospiza caerulescens. METHODS: Two specimens of the Crane hawk were captured in Formosa province, Argentina, their viscera were preserved in 10% formalin and examined in the laboratory. RESULTS: Helminthological analysis revealed the presence of six helminth taxa (one Trematoda, four Nematoda, and one Acanthocephala). The morphometric study of these helminths and its comparison with previous reports, allowed us to describe a new species of Parastrigea (Digenea: Strigeidae) and report new host-parasite associations and geographical records. Parastrigea labiata n. sp. is mainly characterized by having forebody not divided and two long trumpet-shaped projections of dorsal lip, which emerge through the opening. Five taxa, previously known, Synhimantus (Dispharynx) resticula, Synhimantus (Synhimantus) rectus, Microtetrameres sp., Porrocaecum sp. and Centrorhynchus sp. are briefly described. CONCLUSIONS: Previous parasitological studies on G. caerulescens were carried out on material collected between 1817 and 1955, and seven species of helminths were reported. In this study, the six taxa of helminths found constitute new host records, which shows the importance of contemporary studies about this host. All helminths found have heteroxenous life cycles and birds are infected by trophic transmission. Crane hawk's diet includes small vertebrates and to a lesser extent large arthropods. The finding of five helminth species that use invertebrates as intermediate hosts could indicate an important consumption of invertebrates. This research expands the helminthological inventory of Argentinean birds and the knowledge of the helminths of G. caerulescens.

COVID-19 impacts on household solid waste generation in six Latin American countries: a participatory approach.

The COVID-19 pandemic has greatly impacted the Americas, the continent with the highest number of COVID-related deaths according to WHO statistics. In Latin America, strict confinement conditions at the beginning of the pandemic put recycling activity to a halt and augmented the consumption of plastic as a barrier to stop the spread of the virus. The lack of data to understand waste management dynamics complicates waste management strategy adjustments aimed at coping with COVID-19. As a novel contribution to the waste management data gap for Latin America, this study uses a virtual and participatory methodology that collects and generates information on household solid waste generation and composition. Data was collected between June and November 2021 in six countries in Latin America, with a total of 503 participants. Participants indicated that the pandemic motivated them to initiate or increase waste reduction (41%), waste separation (40%), and waste recovery (33%) activities. Forty-three percent of participants perceived an increase in total volume of their waste; however, the quantitative data showed a decrease in household waste generation in Peru (-31%), Honduras (-25%), and Venezuela (-82%). No changes in waste composition were observed. Despite the limited sample size, this data provides a much-needed approximation of household waste generation and composition in the pandemic situation during 2021.

Intercontinental distributions, phylogenetic position and life cycles of species of Apharyngostrigea (Digenea, Diplostomoidea) illuminated with morphological, experimental, molecular and genomic data.

When subjected to molecular study, species of digeneans believed to be cosmopolitan are usually found to consist of complexes of species with narrower distributions. We present molecular and morphological evidence of transcontinental distributions in two species of Apharyngostrigea Ciurea, 1924, based on samples from Africa and the Americas. Sequences of cytochrome c oxidase I and, in some samples, internal transcribed spacer, revealed Apharyngostrigea pipientis (Faust, 1918) in Tanzania (first known African record), Argentina, Brazil, USA and Canada. Sequences from A. pipientis also match previously published sequences identified as Apharyngostrigea cornu (Zeder, 1800) originating in Mexico. Hosts of A. pipientis surveyed include definitive hosts from the Afrotropic, Neotropic and Nearctic, as well as first and second intermediate hosts from the Americas, including the type host and type region. In addition, metacercariae of A. pipientis were obtained from experimentally infected Poecilia reticulata, the first known record of this parasite in a non-amphibian second intermediate host. Variation in cytochrome c oxidase I haplotypes in A. pipientis is consistent with a long established, wide-ranging species with moderate genetic structure among Nearctic, Neotropic and Afrotropic regions. We attribute this to natural dispersal by birds and find no evidence of anthropogenic introductions of exotic host species. Sequences of CO1 and ITS from adult Apharyngostrigea simplex (Johnston, 1904) from Egretta thula in Argentina matched published data from cercariae from Biomphalaria straminea from Brazil and metacercariae from Cnesterodon decemmaculatus in Argentina, consistent with previous morphological and life-cycle studies reporting this parasite-originally described in Australia-in South America. Analyses of the mitochondrial genome and rDNA operon from A. pipientis support prior phylogenies based on shorter markers showing the Strigeidae Railliet, 1919 to be polyphyletic.

Phylogenetic position of Diplostomum spp. from New World herons based on complete mitogenomes, rDNA operons, and DNA barcodes, including a new species with partially elucidated life cycle.

Diplostomum ardeae Dubois, 1969 has seldom been reported since its description from the great blue heron (Ardea herodias L., 1758) in the USA. Sequences obtained in this study from the barcode region of cytochrome c oxidase 1 (CO1) in diplostomids from black-crowned night heron (Nycticorax nycticorax (L., 1758)) in Puerto Rico matched data from D. ardeae from A. herodias in the type region. We also obtained DNA barcodes from morphologically similar diplostomids from a rufescent tiger heron (Tigrisoma lineatum (Boddaert, 1783)) and from metacercariae from eye lenses of Trachelyopterus galeatus (Linnaeus, 1766) from the Paraná River basin in Argentina and Brazil, respectively. Barcodes matched (97-100% identity) in these South American adult and larval specimens as well as in recently published sequences from metacercariae from 11 other siluriform fishes from the same region. Barcodes from the South American species, which we describe as Diplostomum lunaschiae n. sp., differed from those of D. ardeae by 7.2-9.8%, and the new species differs from D. ardeae in its size, pharynx:oral sucker length ratio, egg:body length ratio, and distribution of vitellaria. As in prior phylogenetic analysis of CO1 sequences, both D. ardeae and D. lunaschiae n. sp. were not associated with Diplostomum. In more character-rich analyses of nuclear rDNA and of mitochondrial genomes, D. ardeae was an early divergent member of clades of species of Diplostomum. Consequently, we continue to consider D. ardeae and D. lunaschiae n. sp. members of Diplostomum, in contrast to recent suggestions that these species may belong to a different genus.

Hernia de Grynfelt resuelta por vía laparoscópica: reporte de un caso / Grynfelt ́s hernia resolved laparoscopically: a case report

RESUMEN Las hernias lumbares son una patología rara que involucra herniación de los contenidos intraabdominales o retroperitoneales a través de debilidades congénitas o adquiridas en la pared abdominal posterolateral. El tratamiento quirúrgico es el recomendado, sin embargo, la vía de abordaje aún no está estandarizada en la literatura, pero existe mucha evidencia a favor de la laparoscopía con mejores resultados en el control del dolor posoperatorio, resultados estéticos y menor estancia hospitalaria. Se presenta el caso clínico de una paciente feme-nina de 55 años con cuadro de dolor lumbar izquierdo de 6 meses de evolución que fue diagnosticada de hernia del triángulo posterior por estudio de imagen. La reparación de su defecto herniario fue con tratamiento quirúrgico por vía laparoscópica.Palabras claves: Hernia; cirugía laparoscópica; procedimientos quirúrgicos operativos; patología quirúrgica; informes de caso.

ABSTRACT Lumbar hernia are a rare pathology that involves herniation of the intra-abdominal or retroperitoneal contents through congenital or ac-quired weaknesses in the posterolateral abdominal wall. Surgical treatment is recommended, however, the approach is not yet standard-ized in the literature, but there is much evidence in favor of laparoscopy with better results in postoperative pain control, cosmetic results, and shorter hospital stay. We present the clinical case of a 55-year-old female patient with a 6-month history of left lumbar pain who was diagnosed with posterior triangle hernia by imaging study. The repair of her hernia defect was with laparoscopic surgical treatment.Keywords: Hernia; laparoscopic surgery; operative surgical procedures; surgical pathology; case report.

A new species of Microtetrameres (Nematoda, Tetrameridae) parasitizing Buteogallus urubitinga (Aves, Accipitridae) from northeastern Argentina.

A new tetramerid nematode, Microtetrameres urubitinga n. sp., is described from specimens recovered from the proventriculus of the great black-hawk, Buteogallus urubitinga (Aves: Accipitridae), from Formosa Province, Argentina. The males of the new species are characterized by having spicules unequal (length ratio of spicules 1:3.8-5.9) and dissimilar in shape (right spicule with a simple tip, left spicule with a symmetrical bifurcated tip), caudal papillae arranged asymmetrically (two pairs precloacal and two pairs postcloacal) and cloacal lips highly protruded forming a tube. The gravid females are permanently coiled clockwise or counterclockwise in a spiral and having a tail tapering gradually to a sharp point, with a cuticular fold. This is the first nominal species of Microtetrameres (Travassos, 1915) described parasitizing birds from Argentina. The relationship between the diet of B. urubitinga and the low prevalence of M. urubitinga n. sp. is discussed.

Estatus epiléptico. Factores asociados a una evolución desfavorable en un centro terciario / Status Epilepticus. Prognostic Variables for an Unfavorable Outcome in a tertiary center of care

Resumen Introducción: El Estatus Epiléptico (EE) es una causa frecuente de emergencia neurológica. Escasos son los estudios realizados en Suramérica para evaluar los factores pronósticos de mortalidad y discapacidad en pacientes con EE. Objetivo: Determinar las variables asociadas a una evolución desfavorable (ED) al alta hospitalaria en pacientes con EE. Método: Se realizó un estudio retrospectivo durante el periodo enero 2016-junio 2017. Un total de 26 pacientes fueron diagnosticados con EE en sus diferentes variantes. Se evaluó el efecto de las variables clínicas, radiológicas y electroencefalográficas sobre la evolución hospitalaria final acorde la escala de Rankin. Resultados: 12 (46,2%) de los pacientes tuvieron una ED al alta hospitalaria, con una mortalidad que alcanzó el 23%. Existió un predominio del sexo masculino (76,9%). Las variables asociadas de forma independiente con una ED fueron el número de comorbilidades (p=0.01, OR: 4.27-95%CI1.33-13.6), lesiones en la imagen por Resonancia Magnética (IRM) (p=0.04, OR: 3.92-95%CI1.05-14.61) y el EE refractario (p=0.01, OR: 12.52-95%CI1.85-84.44), y la edad (p=0.07 OR: 1.03-95%CI0.99-1.07). Mientras que, un buen estado clínico inicial acorde la escala de Glasgow fue un factor protector (p=0.00 OR: 0.49-IC95%0.29-0.84) de tener una ED. Conclusiones: Tener una ED se asocia a la edad, el estado clínico inicial del paciente acorde la escala de Glasgow, así como lesiones en la IRM. EE refractario y más de 4 comorbilidades también fueron predictores de una ED al alta hospitalaria.

Abstract Introduction: Status Epilepticus (SE) is a frequent neurologic emergency. Little research has been done in South America to evaluate the prognostic variables of mortality and disability in patients with SE. Objective: To determine the variables associated to an unfavorable outcome at hospital discharge in the patients who were treated for SE. Methods: A retrospective study was performed during the period of January 2016-June 2017. A total of 26 patients were diagnosed of SE and its different variants. The effects of clinical, radiological, and electroencephalographic features on hospital outcome according Rankin scale were evaluated. Results: Twelve (46.2%) patients had an unfavorable outcome at hospital discharge, while the mortality rate reached 23.1%. There was a predominance of males with a 76.9% of all the patients. The independent variables associated with an unfavorable outcome were the number of comorbidities (p=0.01, OR: 4.27-95%CI1.33-13.6), structural lesions on the Magnetic Resonance Image (MRI) (p=0.04, OR: 3.92-95%CI1.05-14.61) and refractory SE (p=0.01, OR: 12.52-95%CI1.85-84.44). There was also a trend for age (p=0.07 OR: 1.03-95%CI0.99-1.07). While an initial good clinical condition, according to the Glasgow Scale represent a protective factor (p=0.00 OR: 0.49-IC95% 0.29-0.84) of an unfavorable outcome. Conclusions: The unfavorable outcome was marginally associated with patient age, clinical status at the onset of SE according to the Glasgow Coma Scale, as well as brain lesions on brain MRI. Refractory SE and more than 4 comorbidities are predictors of an unfavorable outcome at hospital discharge.

Strigeid parasites of Circus buffoni from Argentina, with the description of a new species of Parastrigea Szidat, 1928.

Studying the Helminthological Collection of Museo de La Plata (MLP-He), several specimens of digeneans, recovered parasitizing a long-winged harrier, Circus buffoni (Accipitridae) from Buenos Aires Argentina, were analysed. The morphological and morphometric analysis of these specimens revealed the presence of two strigeid species, one of them new for science. Parastrigea buffoni n. sp. is characterised by a forebody differentiated in a retractile cephalic region with a large opening and a balloon-shaped collar region or collerette, suckers located in cephalic region, holdfast organ with well development dorsal and ventral lips that can emerge through opening, a claviform hindbody, a large copulatory bursa with muscular ring (Ringnapf) and a genital cone well delimited, crossed by a sinuous hermaphroditic duct with internal rugae. The euryxenous parasite, Strigea falconis brasiliana, is briefly described, parasitizing a new host. This is the first record of helminths parasitizing long-winged harrier.

Nematode parasites of the Chilean Flamingo, Phoenicopterus chilensis (Phoenicopteridae) from Central Argentina, with a description of a new species of Tetrameres (Tetrameridae).

During the summer of 2013, several specimens of Phoenicopterus chilensis (Phoenicopteridae) were found dead from unknown causes, in lakes from the endorheic system "Encadenadas del Oeste", Buenos Aires Province, Argentina. Two species of Nematoda were recovered from the proventriculus, one of them new for science. The tetramerid Tetrameres (Tetrameres) salina n. sp. is mainly characterized by having reduced pseudolabia, lips absent, six bifid teeth, males with lateral alae, four rows of somatic spines and length ratio of spicules 1:12-32, and large females with eggs lacking polar filaments. The acuariid, Echinuria skrjabinensis is described and illustrated, this finding represent the second report of this nematode in Argentina and the first record in flamingos. This is the first record of helminths parasitizing wild Chilean Flamingos, but it is not possible to ensure that they accomplish their life cycle in this system of lakes, because the migratory movements of the population of flamingos studied are unknown.

Gasterópodos terrestres de la provincia de Misiones, Argentina / Terrestrial gastropods from Misiones Province, Argentina

The Atlantic Forest represents one of the global priority eco-regions for biodiversity conservation. In Argentina, this is represented by the Paranense Forest, which occupies much of the Misiones Province. In this paper, an updated list of land mollusks from Misiones Province is presented, and its species richness was evaluated comparing protected and unprotected areas. For this, we reviewed La Plata Museum Mollusk Collection, updated the literature review, and developed some field work between 2009 and 2010. For the areographic work, a grid (50x50km) was applied to a Misiones province map. In this region, large areas of native vegetation constituting the Paranaense Forest still persist, and include protected areas such as the Iguazú National Park and Puerto Península Provincial Park. These areas have been the most explored at the malacological level (both terrestrial and aquatic environments), a fact that is consistent with the greater number of records found, which may also be the explanation for the highest number of species recorded in the region. A database containing 497 records was compiled. The number of species occurring in this Province was increased from 28 to 56; 11 of which were exotic species. A total of 38 of the species occurred in protected areas and 53 in unprotected areas; and 25 species were micro-mollusks. Orthalicidae was the family with the highest species number (10) and the widest distribution, occupying 16/20 sampling units. Megalobulimus was the genus found in a greater number of sampling units (14/20). The highest values of specific richness of land gastropods were found in Northern Misiones (R=32). This richness was similar to that previously reported for the Tucumán Province, although species occurring in both provinces were mostly different. The richness in Misiones Province border areas, as the Republic of Paraguay and the state of Santa Catarina (Brazil), was about twice that found in the province. The present study showed the existence of poorly explored areas at malacological level, especially in Central and Eastern Misiones. Data presented here will allow focus future sampling efforts on such areas, so patterns of species distribution can be better defined. Rev. Biol. Trop. 61 (4): 1759-1768. Epub 2013 December 01.

El Bosque Atlántico es una de las eco-regiones prioritarias para la conservación global de la diversidad biológica. En territorio argentino se encuentra representado por la Selva Paranense que ocupa gran parte de la provincia de Misiones. Aquí se presenta una lista actualizada de los moluscos terrestres de la provincia de Misiones, se evalúa su riqueza y se las compara entre áreas protegidas y no protegidas. Se elaboró una base de datos de 497 registros. Se utilizó una grilla de 50x50km sobre el mapa de la provincia de Misiones. Se amplió el número de especies presentes en esta provincia de 28 a 56 (11 exóticas y 25 micromoluscos). En áreas no protegidas se registraron 53 especies y 38 en áreas protegidas. Orthalicidae presentó el mayor número de especies (diez) y la distribución más amplia. Megalobulimus spp. se registró en 14 unidades de muestreo. Los mayores valores de riqueza específica se encontraron en el extremo norte de la provincia (R=32), donde a su vez se registra la mayor cantidad de muestreos. En esta región se mantienen grandes extensiones de vegetación autóctona que conforman la Selva Paranaense y zonas protegidas como el Parque Nacional Iguazú y el Parque Provincial Puerto Península.

[Terrestrial gastropods from Misiones Province, Argentina]. / Gasterópodos terrestres de la provincia de Misiones, Argentina.

The Atlantic Forest represents one of the global priority eco-regions for biodiversity conservation. In Argentina, this is represented by the Paranense Forest, which occupies much of the Misiones Province. In this paper, an updated list of land mollusks from Misiones Province is presented, and its species richness was evaluated comparing protected and unprotected areas. For this, we reviewed La Plata Museum Mollusk Collection, updated the literature review, and developed some field work between 2009 and 2010. For the areographic work, a grid (50 x 50 km) was applied to a Misiones province map. In this region, large areas of native vegetation constituting the Paranaense Forest still persist, and include protected areas such as the Iguazú National Park and Puerto Peninsula Provincial Park. These areas have been the most explored at the malacological level (both terrestrial and aquatic environments), a fact that is consistent with the greater number of records found, which may also be the explanation for the highest number of species recorded in the region. A database containing 497 records was compiled. The number of species occurring in this Province was increased from 28 to 56; 11 of which were exotic species. A total of 38 of the species occurred in protected areas and 53 in unprotected areas; and 25 species were micro-mollusks. Orthalicidae was the family with the highest species number (10) and the widest distribution, occupying 16/20 sampling units. Megalobulimus was the genus found in a greater number of sampling units (14/20). The highest values of specific richness of land gastropods were found in Northern Misiones (R=32). This richness was similar to that previously reported for the Tucumán Province, although species occurring in both provinces were mostly different. The richness in Misiones Province border areas, as the Republic of Paraguay and the state of Santa Catarina (Brazil), was about twice that found in the province. The present study showed the existence of poorly explored areas at malacological level, especially in Central and Eastern Misiones. Data presented here will allow focus future sampling efforts on such areas, so patterns of species distribution can be better defined.

Selective growth of palladium and titanium dioxide nanostructures inside carbon nanotube membranes.

Hybrid nanostructured arrays based on carbon nanotubes (CNT) and palladium or titanium dioxide materials have been synthesized using self-supported and silicon-supported anodized aluminum oxide (AAO) as nanoporous template. It is well demonstrated that carbon nanotubes can be grown using these membranes and hydrocarbon precursors that decompose at temperatures closer to 600°C without the use of a metal catalyst. In this process, carbonic fragments condensate to form stacked graphitic sheets, which adopt the shape of the pores, yielding from these moulds' multi-walled carbon nanotubes. After this process, the ends of the tubes remain open and accessible to other substances, whereas the outer walls are protected by the alumina. Taking advantage of this fact, we have performed the synthesis of palladium and titanium dioxide nanostructures selectively inside carbon nanotubes using these CNT-AAO membranes as nanoreactors.

Differences on allocation of available resources, in growth, reproduction, and survival, in an exotic gastropod of Physidae compared to an endemic one

Physa acuta Draparnaud, 1805 es un gasterópodo invasor que puede afectar las poblaciones de especies locales. En Argentina, se encuentra ampliamente distribuida y en altas densidades, incluso en ambientes habitados por la especie nativa Stenophysa marmorata Guilding, 1828. Su predominancia podría ser explicada por un uso más exitoso de la energía en las demandas funcionales (crecimiento, reproducción y supervivencia) con respecto a S. marmorata. El objetivo de este trabajo fue comparar las constantes de crecimiento de ambas especies, teniendo en cuenta también los valores de supervivencia y fecundidad, en condiciones de laboratorio. Los individuos nacidos el mismo día fueron agrupados de a cuatro por acuario y mantenidos en condiciones controladas de alimentación, luz y temperatura. La longitud máxima de conchilla de los caracoles fue medida semanalmente, y la constante de crecimiento fue calculada usando la ecuación de Von Bertalanffy. El número de huevos y sobrevivientes era contado cada semana. Los ejemplares de S. marmorata nacieron con un tamaño mayor que los de Physa acuta e invirtieron más energía en el crecimiento, retardando su madurez sexual. Esto se tradujo en una desventaja en fecundidad y supervivencia con respecto a P. acuta, la cual presentó una constante de crecimiento menor pero maduró más tempranamente y sobrevivió más tiempo. Además, P. acuta no vio afectado su crecimiento por la reproducción y presentó un período reproductivo más prolongado, depositando así una mayor cantidad de huevos que S. marmorata.

Physa acuta Draparnaud, 1805 is an invasive gastropod that can affect local species. In Argentina, it is widespread and abundant, even in environments inhabited by the native species Stenophysa marmorata Guilding, 1828. Its predominance raises the question whether this could be explained by a more successful energy allocation in functional requirements (growth, reproduction and survival) compared to S. marmorata. This study was aimed at comparing growth rates, as well as survival and fecundity, between both species under laboratory conditions. Individuals born on the same day were grouped in four per aquaria and kept under controlled conditions of food, light, and temperature. Snails were weekly measured (maximum shell length), and growth rates were calculated using the Von Bertalanffy's equation. The number of eggs and survivors were grouped by week. Stenophysa marmorata was larger at birth than Physa acuta and invested more energy in growth, delaying sexual maturity. This resulted in a disadvantage in fecundity and survival compared to P. acuta, which had a lower growth rate but matured earlier and survived longer. Furthermore, the growth of P. acuta was not affected by reproduction, its reproductive period was longer, consequently with more eggs laid than S. marmorata.

Differences on allocation of available resources, in growth, reproduction, and survival, in an exotic gastropod of Physidae compared to an endemic one

Physa acuta Draparnaud, 1805 es un gasterópodo invasor que puede afectar las poblaciones de especies locales. En Argentina, se encuentra ampliamente distribuida y en altas densidades, incluso en ambientes habitados por la especie nativa Stenophysa marmorata Guilding, 1828. Su predominancia podría ser explicada por un uso más exitoso de la energía en las demandas funcionales (crecimiento, reproducción y supervivencia) con respecto a S. marmorata. El objetivo de este trabajo fue comparar las constantes de crecimiento de ambas especies, teniendo en cuenta también los valores de supervivencia y fecundidad, en condiciones de laboratorio. Los individuos nacidos el mismo día fueron agrupados de a cuatro por acuario y mantenidos en condiciones controladas de alimentación, luz y temperatura. La longitud máxima de conchilla de los caracoles fue medida semanalmente, y la constante de crecimiento fue calculada usando la ecuación de Von Bertalanffy. El número de huevos y sobrevivientes era contado cada semana. Los ejemplares de S. marmorata nacieron con un tamaño mayor que los de Physa acuta e invirtieron más energía en el crecimiento, retardando su madurez sexual. Esto se tradujo en una desventaja en fecundidad y supervivencia con respecto a P. acuta, la cual presentó una constante de crecimiento menor pero maduró más tempranamente y sobrevivió más tiempo. Además, P. acuta no vio afectado su crecimiento por la reproducción y presentó un período reproductivo más prolongado, depositando así una mayor cantidad de huevos que S. marmorata.

Physa acuta Draparnaud, 1805 is an invasive gastropod that can affect local species. In Argentina, it is widespread and abundant, even in environments inhabited by the native species Stenophysa marmorata Guilding, 1828. Its predominance raises the question whether this could be explained by a more successful energy allocation in functional requirements (growth, reproduction and survival) compared to S. marmorata. This study was aimed at comparing growth rates, as well as survival and fecundity, between both species under laboratory conditions. Individuals born on the same day were grouped in four per aquaria and kept under controlled conditions of food, light, and temperature. Snails were weekly measured (maximum shell length), and growth rates were calculated using the Von Bertalanffy's equation. The number of eggs and survivors were grouped by week. Stenophysa marmorata was larger at birth than Physa acuta and invested more energy in growth, delaying sexual maturity. This resulted in a disadvantage in fecundity and survival compared to P. acuta, which had a lower growth rate but matured earlier and survived longer. Furthermore, the growth of P. acuta was not affected by reproduction, its reproductive period was longer, consequently with more eggs laid than S. marmorata.

[Latin American malacology. Freshwater mollusks from Argentina]. / Malacología Latinoamericana. Moluscos de agua dulce de Argentina.

A report and an updated list with comments on the species of freshwater molluscs of Argentina which covers an area of 2 777 815 km2 is presented. Distributions of Gastropoda and Bivalvia families, endemic, exotic, invasive as well as entities of sanitary importance are also studied and recommendations on their conservation are provided. Molluscs related to the Del Plata Basin have been thoroughly studied in comparison to others areas of the country. This fauna exhibits relatively the biggest specific richness and keeps its affinity with the fauna of other regions of the basin in areas of Paraguay and Brasil. The 4 500 records of molluscs considered in this paper arise from the study of the collections of Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires; Museo de La Plata, La Plata and Fundación "Miguel Lillo", Tucumán. These institutions keep very important collections of molluscs in southern South America. Field information has recently been obtained and localities cited by other authors are also included in the data base. Until today, 166 species have been described, 101 belonging to 10 families of Gastropoda and 65 to 7 of Bivalvia. Families with highest specific richness are Lithoglyphidae (22) and Sphaeriidae (25), respectively. The number of endemic species (those present only in Argentina) by family is: Gastropoda: Ampullariidae (1), Cochliopidae (10), Lithoglyphidae (11), Thiariidae (3), Chilinidae (11), Lymnaeidae (2) and Physidae (2?); Bivalvia: Hyriidae (1?); Etheriidae (1?) and Sphaeriidae (10). Families with a distribution that comprise almost the whole country are: the Sphaeriidae and the gastropods Cochliopidae, Chilinidae and Lymnaeidae. Families Erodonidae and Solecurtidae (Bivalvia) were registered in mixohaline environments from Buenos Aires province. Gastropod families Thiaridae and Glacidorbiidae show a very restricted distribution. The rest of the families are present mainly in the center and north of the country. Species of sanitary interest are the propagators of: schistosomiasis -Biomphalaria peregrina, B. straminea y B. tenagophila, Planorbidae-, fasciolasis -Lymnaea viatrix and L. columnella, Lymnaeidae- and dermatitis -Chilina gibbosa and C. fluminea, Chilinidae. Invasive species are: Corbicula fluminea (Corbiculidae) and Limnoperna fortunei (Mytilidae). The construction of new areas for the protection and conservation of the high risk endemic species of freshwater molluscs is a priority. It is necessary to give special attention to the species of the patagonic mountain range and of the mesopotamic area of the Del Plata Basin.