Carnivore coexistence without competition: giant otters are more nocturnal around dens than sympatric neotropical otters.

Nocturnal activity of tropical otters is rarely reported. To date no studies have documented den use by sympatric giant (Pteronura brasiliensis) and neotropical otters (Lontra longicaudis). We used camera-traps to monitor den use by sympatric otters along an equatorial Amazonian river. Camera-traps provided evidence that giant otters were more nocturnal around dens than sympatric neotropical otters. Nocturnal activity was recorded in 11% of giant otter photos (n = 14 of 125 photos), but was recorded only once for neotropical otters. Den use by giant and neotropical otters overlapped spatially and temporally but not concurrently. We hypothesize that previously reported nocturnal activity in neotropical otters is facilitated by the absence or low density of giant otters. Our results also underscore the need to use complementary techniques together with den counts for monitoring otters as sympatric species can use the same dens.

Anomalous origin of the right subclavian artery in a Neotropical otter (Lontra longicaudis, Olfers-1818).

The Neotropical otter (Lontra longicaudis) is a mustelid distributed geographically from Mexico to Argentina. Anomalous origins of the aortic arch branches are rarely reported in wild carnivorans. Therefore, this study aimed to report the anomalous branching of the aortic arch in one formaldehyde-fixed specimen of L. longicaudis. The aortic arch provided three branches: the bicarotid trunk and the left and right subclavian arteries. The latter passed dorsally to the esophagus toward the right side without a mark of compression at the esophagus. This is the first report of an anomalous origin of the right subclavian artery in L. longicaudis.

Sonographic features of abdominal organs in healthy captive Neotropical otters (Lontra longicaudis).

This study aimed to assess the sonographic features of abdominal organs in healthy captive Neotropical otters (Lontra longicaudis). The sonograph showed that the urinary bladder was located in the caudal abdomen and its content was uniformly anechoic. The bladder wall had three layers: outer hyperechoic serosa, hypoechoic muscular layer and hyperechoic mucosa. The mean total wall thickness was 0.10 cm. The splenic parenchyma had a homogeneous echotexture with greater echogenicity than that of the left renal cortex and liver. The borders were regular and tapered. Rugal folds were observed in the stomach when undistended. The mean gastric wall thickness was 0.28 cm and five distinct layers were visible. The liver had smooth contours, and division of the hepatic lobes was not precisely visualized. The hepatic parenchyma had a homogeneous echotexture with greater echogenicity as compared to the right kidney and lesser echogenicity than that of the spleen. The gallbladder appeared as an oval or rounded structure in the transverse plane, filled with homogeneous anechogenic content; the wall was thin, regular and hyperechoic, with a mean thickness of 0.09 cm. The kidneys had a lobulated appearance with renicular subunits. The mean total length of the kidneys in longitudinal plane was 6.18 cm for the left and 6.27 cm for the right. Each reniculus was covered by an echogenic capsule, and the medullary region was more hypoechogenic than the cortical region. In conclusion, sonographic features in most of the abdominal organs in Neotropical otters are similar to the ultrasound patterns observed in healthy dogs and cats, except for kidneys with reniculi.

Noteworthy records of the ticks Ornithodoros rostratus and Amblyomma sculptum parasitizing Pteronura brasiliensis in the central-western region of Brazil, with pathogen investigation notes.

A male of Pteronura brasiliensis (Carnivora: Mustelidae) was found dead on the banks of the Rio Negro, in the Pantanal wetlands of Mato Grosso do Sul state, Aquidauana municipality. Two ticks found attached to its skin were morphologically identified as a second-instar nymph of Ornithodoros rostratus (Argasidae) and a male of Amblyomma sculptum (Ixodidae). In order to complement the morphological identification, these tick specimens were subjected to DNA extraction, and tested using PCR assays to confirm the molecular identity the specimens. Also, the tick DNA samples were tested and were negative in the PCR assays for all the pathogens tested. We also examined 30 batches, consisting of 174 individuals of O. rostratus deposited in the Acari Collection of the Butantan Institute, and we found material from four Brazilian states, including one batch containing 2 males and 2 females from Aquidauana, of Mato Grosso do Sul state, collected from the soil. This was therefore the first record of O. rostratus parasitizing P. brasiliensis and the first locality record (Aquidauana). Likewise, A. sculptum is commonly found in the Pantanal and is reported here for the second time parasitizing the giant otter, which is a host little studied regarding the ectoparasites.

Amblyomma sculptum ticks on a giant otter from the Brazilian Pantanal.

The giant otter (Pteronura brasiliensis) is a semiaquatic carnivore and a top predator in the trophic chain, considered a sentinel of freshwater ecosystems. Ticks are common ectoparasites of worldwide distribution and potential vectors of diseases. In this study, we report the ectoparasitism by ticks on a giant otter carcass found during monitoring activity at the Negro River, that holds a viable population of this endangered species in the Brazilian Pantanal. A total of three tick specimens were collected: two adults were identified as Amblyomma sculptum and a nymph as Amblyomma spp. There is a lack of information about the health of free-ranging giant otters and this report contributes to elucidate some of the host-parasite relationships, although much more research is needed to expand the knowledge about which kinds of pathogens are circulating in the species, especially among those transmitted by ticks.

Human disturbances and the daytime activity of sympatric otters along equatorial Amazonian rivers.

Background: Previous studies suggest coexistence between sympatric neotropical (Lontra longicaudis) and giant otters (Pteronura brasiliensis) maybe facilitated by temporal and spatial differences in activity. Yet, to date there has been no systematic evaluation of activity of these species in sympatry. Here we use extensive multi-year field data to compare temporal and spatial patterns in the diurnal activity of sympatric giant and neotropical otters to answer three questions: Do temporal patterns in daytime river use change in relation to seasonal river levels (low, rising, high and declining river levels), do they change due to human disturbances (boats and fishing nets) and do patterns in neotropical otter activity change due to the presence of the larger sized giant otter? Methods: Direct observations of both species were recorded using standardized boat surveys along 218 km of rivers over 53 months during nine years (2011-2013 and 2015-2020). Complementary techniques (Generalized Additive Models, Kernel density estimates and non-parametric tests,) were used to compare diurnal activity patterns along rivers subdivided into 41 river reaches. Results: The presence of giant otters decreased threefold from 67% of the least disturbed reaches (few boats no fishing nets) to 18% of the most disturbed reaches with many boats and fishing nets. In contrast neotropical otter presence nearly doubled from 44% of the least disturbed to 73% of the most disturbed reaches with fewest giant otter detections. Both species were observed across all daytime hours but were observed rarely on the same day. There was no evidence to suggest simultaneous use of the same reach. When species were detected on the same day, they were separated spatially (median distance between species 12.5 km) and temporally (median time difference 3.0 hours). There was little change in activity of either species among seasons. Giant otters were less active in river reaches with fishing nets and boat use, whereas neotropical otter activity did not appear to be strongly affected by these activities. Conclusions: Our findings support evidence that diurnal activity in both otter species is flexible, with daytime activity changing due to human disturbances in the case of giant otters.

Occurrence and temporal distribution of oxandrolone and meclizine in surface water, sediments, fish muscle and otter feces of the Ayuquila-Armería basin, Mexico.

Aquatic ecosystems worldwide are strongly influenced by the productive activities of a region. These activities can generate pollution by compounds with little-known or unknown characteristics and without regulation. Emerging contaminants are a group of compounds that have worldwide begun to be frequently detected in the environment, raising concern about their possible adverse effects on human and environmental health. Thus, it is important to generate a broader panorama of the dissemination of contaminants of emerging concern in the environment, implement actions to regulate their usage. This study aims to evaluate the occurrence and temporal distribution of oxandrolone and meclizine in surface water, sediments, tilapia muscle, and otter feces of the Ayuquila-Armería river, Mexico. Oxandrolone was detected in 55 % of the total analyzed samples, while meclizine was present in 12 %. In surface water, oxandrolone was present in 56 % of the samples, while meclizine in 8 %. In sediments, oxandrolone was detected in 45 % and meclizine was not detected. In tilapia muscle, oxandrolone was present in 47 % of samples and meclizine was not detected. In otters feces samples, oxandrolone and meclizine were present in 100 %. Regardless of the season (wet or dry), oxandrolone was detected in all four sample types, while meclizine was only detected in surface water and otter feces samples. Oxandrolone in the aquatic ecosystem of the Ayuquila-Armería basin showed that season variation generates a significant effect on their concentrations, especially in surface water and sediments. Meclizine did not show temporal variations either in seasons or between years. Particularly, oxandrolone concentrations presented an influence with respect to the sites that present continuous residual discharges to the river. In this sense, this study could be considered as a starting point for further routine monitoring of emerging contaminants to support regulation policies regarding their use and disposal.

Metastatic exocrine pancreatic adenocarcinoma in a giant otter (Pteronura brasiliensis).

Neoplasms of the exocrine pancreas are uncommon in domestic animals and rarely occur in wildlife. This article describes the clinical and pathological findings of one case of metastatic exocrine pancreatic adenocarcinoma in an 18-year-old giant otter (Pteronura brasiliensis) in captivity with a history of inappetence and apathy. Abdominal ultrasonography was inconclusive, and tomography revealed a neoplasm affecting the urinary bladder and hydroureter. During the anaesthesia recovery, the animal presented a cardiorespiratory arrest and died. Grossly, there were neoplastic nodules in the pancreas, urinary bladder, spleen, adrenal glands, and mediastinal lymph node. Microscopically, all nodules were composed of a malignant hypercellular proliferation of epithelial cells with acinar or solid disposition, supported by a sparse fibrovascular stroma. Neoplastic cells were immunolabeled with antibodies to Pan-CK, CK7, CK20, PPP and chromogranin A. Approximately 25% of the cells were positive for the presence of Ki-67 too. Pathological and immunohistochemical findings confirmed the diagnosis of metastatic exocrine pancreatic adenocarcinoma.

Variation of local zoological knowledge about Southern river otter and other semi-aquatic mammals in Nahuel Huapi National Park (Argentina).

BACKGROUND: The huillín (Lontra provocax, Thomas 1908) is an otter, endemic to southern Argentina and Chile. It is in danger of extinction. In the Nahuel Huapi National Park and surroundings is the only freshwater, known and stable population of huillín in Argentina. In this park, several urban and rural centers coexist with this species. The main objective of our work was to answer: How does the local zoological knowledge (LZK) vary about the huillín, particularly its identification and sighting, among people from different social groups, with different ages and gender, who live in the rural or urban environment and with different periods of permanence in the place? METHODS: Ninety-six written interviews were conducted using visual stimuli to ensure that interviewees refer to the huillín. In addition, we also inquire about the LZK of other species with which it can be confused. Additional open interviews were conducted with participants who observed the huillín to determine the georeferencing of the reported sites and include them on a final map. RESULTS: 95% of people identified the huillín and this was confused with the coipo in 3% and with the american mink, in 5%. The results show that, in general, the LZK did not vary significantly with the sociocultural characteristics of the participants, showing a remarkable homogeneity. However, people in rural areas are more likely to observe the species than people in urban areas. Moreover, people between 20 and 40 years of age are more likely to observe the huillín. The LZK mapping has identified areas that are consistent with and/or adjacent to official source records. Other areas have also been identified that may provide new information. CONCLUSION: With this participatory work, we realize that the species is recognized by urban and rural inhabitants and very few confused it. The homogeneity in the LZK found constitutes a kick for the realization of other participatory studies that promote lines of research, action and management that improve the quality of the environments where the only freshwater, known and stable population of the huillín in Argentina lives.

Local intensity of artisanal gold mining drives mercury accumulation in neotropical oxbow lake fishes.

Driven by surges in global gold prices and additional socio-economic factors, artisanal small-scale gold mining (ASGM) in the Global South is increasing and driving emissions of significant quantities of mercury (Hg) into the air and freshwater. Hg can be toxic to animal and human populations and exacerbate the degradation of neotropical freshwater ecosystems. We examined drivers of Hg accumulation in fish that inhabit oxbow lakes of Peru's Madre de Dios, a region with high biodiversity value and increasing human populations that depend on ASGM. We hypothesized that fish Hg levels would be driven by local ASGM activities, by environmental Hg exposure, by water quality, and by fish trophic level. We sampled fish in 20 oxbow lakes spanning protected areas and areas subject to ASGM during the dry season. Consistent with previous findings, Hg levels were positively associated with ASGM activities, and were higher in larger, carnivorous fish and where water had lower dissolved oxygen levels. In addition, we found a negative relationship between fish mercury levels associated with ASGM and the occurrence of the piscivorous giant otter. The link between fine-scale quantification of spatial ASGM activity and Hg accumulation, as indicated by the result that in the lotic environment, localized effects of gold mining activities are stronger drivers (77 % model support) of Hg accumulation than environmental exposure (23 %) constitutes a novel contribution to a growing body of literature on Hg contamination. Our findings provide additional evidence of high Hg exposure risks to neotropical human and top carnivore populations subject to the impacts of ASGM, which depend on freshwater ecosystems undergoing gradual degradation. The documented spatial variation in Hg accumulation and increased Hg levels in carnivorous fish should serve as a warning to human communities in Madre de Dios to avoid the proximity of high-intensity gold mining areas and minimize local carnivorous fish consumption.

Neotropical mustelids: fecal metabolome diversity and its potential for taxonomic discrimination.

Chemical profiles of non-invasive biological material, such as feces, have great potential to study elusive animals or those with low population densities. Here, we use a metabolomic approach to evaluate Neotropical mustelids as a biological model to describe the diversity of the metabolites present in fecal samples, as well as to evaluate the potential of chemical profiles for taxonomic discrimination. We collected fecal samples from captive individuals of 5 species of mustelids occurring in Brazil and analyzed them by liquid chromatography coupled to high-resolution mass spectrometry. Over 200 compounds have been annotated; "bile acids, alcohols and derivatives" was the most expressive class in the metabolome of all the species. We successfully discriminated 3 taxonomic groups: 1-tayra (Eira barbara); 2-otters (Lontra longicaudis and Pteronura brasiliensis; 1); and 3-grisons (Galictis vittata and Galictis cuja). Several compounds seemed to be associated with food intake and the digestive process, while others were found for the first time in Neotropical mustelids. We concluded that mustelids show high metabolome diversity and that species-specific identification through metabolomic profiles is possible, thus contributing to the development and implementation of additional non-invasive approaches in the study of mustelids.

Congenital renal hypoplasia and contralateral kidney failure in a giant otter (Pteronura brasiliensis) ex situ in Southeastern Brazil

Renal hypoplasia is incomplete development of the kidneys, in which fewer than normal numbers of nephrons are present at birth. This report is the first of these conditions in mustelids. A female adult giant otter (Pteronura brasiliensis), ex situ, presented clinically an unusual behavior with prostration, anorexia, hiding in the shelter, ataxia, paraparesis, and death in a clinical course of one day. At the postmortem exam, the left kidney was markedly enlarged and pale and the right kidney was severely reduced and had mild to moderate capsular thickening. Histologically, the left kidney had mineralization, proliferation of fibrous connective tissue and a mild neutrophilic infiltrate. The right kidney presented a reduced number of glomeruli, tubular atrophy and an increase in fibrous connective tissue, which were findings compatible with congenital kidney hypoplasia. Due the clinical condition of the animal, gross and microscopic findings, the cause of death was established as kidney failure induced by renal hypoplasia.(AU)

Optimal foraging of Neotropical otters (Carnivora: Mustelidae) in an urban river and predominance of generalist and sedentary fish in their diet

Lontra longicaudis Olfers, 1818 is a semi-aquatic carnivore widely distributed in the Neotropical region. Understanding their diet contributes to an indirect understanding of their ecology and the composition of the local fauna. To this end, we analyzed 109 fecal samples and identified 238 morphological structures; these samples were collected between May 2006 and September 2007 from the Santa Lúcia Biological Station (SLBS) in southeastern Brazil. The area is intersected by the Timbuí River, which arrives at the site after crossing the urban perimeter of the city of Santa Teresa in the state of Espírito Santo. We found a predominance of fish in the otters' diets (82%), mainly cichlids (50%), which are fish with sedentary habits and low mobility levels. The crustacean Trichodactylus fluviatilis Latreille, 1828 was the third most consumed taxon; this occurred mainly during the rainy season, corresponding to the crustacean's reproductive period, when it is more vulnerable to predation. Otters exhibited a seasonal variation in their prey selectivity. Furthermore, they displayed opportunistic foraging behavior, as the most preyed fish were those with both low mobility and a high frequency in the environment, followed by fish with high mobility and high frequency, and then those with low mobility and low frequency. We concluded that the feeding habits of the otters in the SLBS are in line with the optimal foraging theory since prey selection was optimized through the balance between net energy gained and the energy costs of foraging.

Medium and large-sized mammals of a private protected wetland in the Cerrado-Amazon biological corridor, Brazil / Mamíferos de médio e grande porte em uma área alagável protegida no corredor biológico Cerrado-Amazônia, Brasil

Brazil is the worlds richest country in biodiversity, including mammal species. In the Brazilian Cerrado biome, mammalian diversity is vast, with about 251 species, 32 of them are endemic and 22 listed as threatened species. In this work, we investigated species diversity of medium- and large-sized mammals in the private protected area RPPN Pontal do Jaburu (RPPN-PJ) and its surroundings, which is a flooded area located in an important biological corridor in the Cerrado-Amazon ecotone zone, a priority area for biodiversity conservation in Brazil. We used camera-trapping, active search (night and day), and track survey during dry season (Apr Aug 2016). We recorded 29 mammal species, being the Carnivora order the most representative with 11 species. Regarding threat status, 35.7% of the recorded species were listed as threatened in Brazil and 32.1% worldwide. We highlight the high relative frequency of threatened species records such as Tapirus terrestris, Panthera onca, Blastocerus dichotomus, Pteronura brasiliensis, Priodontes maximus, and other, as well as the presence of the newly described aquatic mammal species Inia araguaiaensis. We stress the importance of RPPN-PJ and its surroundings for mammal conservation, which include complex habitats (wetlands) located in an important ecotone zone.(AU)

O Brasil é o país mais rico em biodiversidade no mundo, incluindo espécies de mamíferos. No bioma Cerrado, a diversidade de mamíferos é enorme, com cerca de 251 espécies, sendo 32 delas endêmicas e 22 listadas como ameaçadas de extinção. Neste estudo, investigamos a diversidade de espécies de mamíferos de médio e grande porte da RPPN Pontal do Jaburu (RPPN-PJ) e seu entorno, que é uma floresta de inundação localizada em um importante corredor biológico na zona de ecótono Cerrado-Amazonia, uma área prioritária para conservação da biodiversidade no Brasil. Os dados foram coletados por armadilhas fotográficas, busca ativa (noturna e diurna) e identificação de pegadas durante a estação seca (abril - agosto de 2016). Registramos um grande número de espécies de mamíferos (n = 29), sendo a ordem carnívora a mais representativa com 11 espécies. Com relação ao status de ameaça, 34,5% das espécies registradas foram listadas como ameaçadas na lista vermelha do Brasil e 20,7% na lista vermelha da IUCN. Destacamos a alta frequência relativa de registros de espécies ameaçadas como Tapirus terrestris, Panthera onca, Blastocerus dichotomus, Pteronura brasiliensis, Priodontes maximus, bem como a presença da recém descrita espécie de mamífero aquático Inia araguaiaensis. Nós discutimos a importância da RPPN-PJ e seus arredores para a conservação de espécies de mamíferos, onde inclui habitats complexos (áreas de inundação) localizados em uma importante zona de ecótono. Os resultados reforçam a relevância desta área para a conservação de mamíferos.(AU)

Medium and large-sized mammals of a private protected wetland in the Cerrado-Amazon biological corridor, Brazil / Mamíferos de médio e grande porte em uma área alagável protegida no corredor biológico Cerrado-Amazônia, Brasil

Brazil is the world’s richest country in biodiversity, including mammal species. In the Brazilian Cerrado biome, mammalian diversity is vast, with about 251 species, 32 of them are endemic and 22 listed as threatened species. In this work, we investigated species diversity of medium- and large-sized mammals in the private protected area RPPN Pontal do Jaburu (RPPN-PJ) and its surroundings, which is a flooded area located in an important biological corridor in the Cerrado-Amazon ecotone zone, a priority area for biodiversity conservation in Brazil. We used camera-trapping, active search (night and day), and track survey during dry season (Apr – Aug 2016). We recorded 29 mammal species, being the Carnivora order the most representative with 11 species. Regarding threat status, 35.7% of the recorded species were listed as threatened in Brazil and 32.1% worldwide. We highlight the high relative frequency of threatened species records such as Tapirus terrestris, Panthera onca, Blastocerus dichotomus, Pteronura brasiliensis, Priodontes maximus, and other, as well as the presence of the newly described aquatic mammal species Inia araguaiaensis. We stress the importance of RPPN-PJ and its surroundings for mammal conservation, which include complex habitats (wetlands) located in an important ecotone zone.

O Brasil é o país mais rico em biodiversidade no mundo, incluindo espécies de mamíferos. No bioma Cerrado, a diversidade de mamíferos é enorme, com cerca de 251 espécies, sendo 32 delas endêmicas e 22 listadas como ameaçadas de extinção. Neste estudo, investigamos a diversidade de espécies de mamíferos de médio e grande porte da RPPN Pontal do Jaburu (RPPN-PJ) e seu entorno, que é uma floresta de inundação localizada em um importante corredor biológico na zona de ecótono Cerrado-Amazonia, uma área prioritária para conservação da biodiversidade no Brasil. Os dados foram coletados por armadilhas fotográficas, busca ativa (noturna e diurna) e identificação de pegadas durante a estação seca (abril - agosto de 2016). Registramos um grande número de espécies de mamíferos (n = 29), sendo a ordem carnívora a mais representativa com 11 espécies. Com relação ao status de ameaça, 34,5% das espécies registradas foram listadas como ameaçadas na lista vermelha do Brasil e 20,7% na lista vermelha da IUCN. Destacamos a alta frequência relativa de registros de espécies ameaçadas como Tapirus terrestris, Panthera onca, Blastocerus dichotomus, Pteronura brasiliensis, Priodontes maximus, bem como a presença da recém descrita espécie de mamífero aquático Inia araguaiaensis. Nós discutimos a importância da RPPN-PJ e seus arredores para a conservação de espécies de mamíferos, onde inclui habitats complexos (áreas de inundação) localizados em uma importante zona de ecótono. Os resultados reforçam a relevância desta área para a conservação de mamíferos.

First report of myiasis caused by Cochliomyia hominivorax in free-ranging giant otter (Pteronura brasiliensis).

Giant otters are territorial semi-aquatic mammals. It is common to find several individuals exhibiting wounds and scars due to intraspecific conflicts. Myiasis is a parasitic infestation on living tissues of vertebrates caused by dipterous larvae, that usually develops in freshly open wounds and can seriously threaten the host's health. Ectoparasites seem to be rare among giant otters and myiasis had not been recorded in this species until now. Here, is presented one record of myiasis in a free-ranging giant otter found dead in the Pantanal, Brazil. An ulcerative lesion was found in the frontoparietal region, from which 22 larvae were recovered and identified as Cochliomyia hominivorax. The low occurrence of ectoparasites in giant otters might reflect their semi-aquatic habits and their grooming behavior, which makes it difficult for parasites to remain on the skin. The injured otter probably got the larvae after an intraspecific fight. Agonistic encounters between groups of giant otters have been reported before and these fights can result in serious wounds or even death. It was hypothesized that the myiasis caused by C. hominivorax deteriorated the health of the infested giant otter, which prevented recovery and accelerated its death.

Anthropogenic influences on the distribution of a threatened apex-predator around sustainable-use reserves following hydropower dam installation.

Although previous studies demonstrate declines in many large bodied species following hydropower dam installation, others suggest that some species, including the giant otter (Pteronura brasiliensis) may return to newly created reservoir habitats. Yet, there is a lack of evidence to support such theories. Here, we analyzed the effects of a hydropower dam on giant otters using a before-after control-impact study design in the eastern Brazilian Amazon. We collected data 3 years before (2011-2012 and 2015) and after (2017-2019) dam construction, totaling 6,459 km of surveys along rivers with 43 direct sightings of giant otters. Contrary to expectations, our results revealed that giant otters did not remain nor did they return to the dam reservoir. Beyond the zone directly impacted by the dam giant otter occurrence and relative abundance declined next to sustainable-use reserves where the river was more intensely used by people. Our study showed that in the absence of active management sustainable-use reserves and low human density were not sufficient to maintain this apex-predator. Our findings suggest a need to proactively create and maintain areas with low levels of anthropogenic disturbance to enable sustainable coexistence between energy demands and biodiversity across Amazonia.

Phylogenomics of the world's otters.

Comparative whole-genome analyses hold great power to illuminate commonalities and differences in the evolution of related species that share similar ecologies. The mustelid subfamily Lutrinae includes 13 currently recognized extant species of otters,1-5 a semiaquatic group whose evolutionary history is incompletely understood. We assembled a dataset comprising 24 genomes from all living otter species, 14 of which were newly sequenced. We used this dataset to infer phylogenetic relationships and divergence times, to characterize patterns of genome-wide genealogical discordance, and to investigate demographic history and current genomic diversity. We found that genera Lutra, Aonyx, Amblonyx, and Lutrogale form a coherent clade that should be synonymized under Lutra, simplifying the taxonomic structure of the subfamily. The poorly known tropical African Aonyx congicus and the more widespread Aonyx capensis were found to be reciprocally monophyletic (having diverged 440,000 years ago), supporting the validity of the former as a distinct species. We observed variable changes in effective population sizes over time among otters within and among continents, although several species showed similar trends of expansions and declines during the last 100,000 years. This has led to different levels of genomic diversity assessed by overall heterozygosity, genome-wide SNV density, and run of homozygosity burden. Interestingly, there were cases in which diversity metrics were consistent with the current threat status (mostly based on census size), highlighting the potential of genomic data for conservation assessment. Overall, our results shed light on otter evolutionary history and provide a framework for further in-depth comparative genomic studies targeting this group.

Study of feces of neotropical otters (Lontra longicaudis) in the Ayuquila-Armería basin, Mexico as biomonitors of the spatiotemporal distribution of pesticides.

The pesticides used have contributed to increasing food production; it has also caused them to be found in most ecosystems and have negative effects on biota. The neotropical otter (Lontra longicaudis) is vulnerable to pesticide accumulation and is characterized by being elusive, so it is necessary to address the use of indirect techniques that evaluate its populations' state in an efficient, logistically simple, and non-invasive way. This study aimed to determine the concentration of 20 pesticides in neotropical otter feces in the Ayuquila-Armería basin and to describe the spatiotemporal variation of these pesticides. The presence of 11 pesticides was determined. Imazalil, picloram, and malathion the pesticides with the highest concentrations; emamectin, λ-cyhalothrin, methomyl, and picloram were present in all samples. Emamectin was the only pesticide that presented significant differences concerning the temporality of the samplings, presenting higher concentrations in the wet season. Molinate concentrations showed significant differences concerning the location of the sampling sections in the basin; the lower part of the basin presented higher concentrations. The distribution of the populations of L. longicaudis in the Ayuquila-Armería basin does not respond to the degree of contamination by pesticides in surface waters or to the proximity to agricultural activities, and this in places with evident chemical and organic contamination and human presence. The use of otter feces for pesticide monitoring is an accepted non-invasive method to assess the degree of exposure and can be used to determine sites with pollution problems.

Canine distemper virus and canine adenovirus type-2 infections in neotropical otters (Lontra longicaudis) from Southern Brazil.

All descriptions of infectious diseases affecting otters were published in the Northern Hemisphere, with no occurrence identified in neotropical otters (Lontra longicaudis). Consequently, a retrospective histopathological study using archival tissue samples from six free-living neotropical otters was done to investigate the possible occurrence of disease patterns associated with common viral infectious disease agents of the domestic dogs. Immunohistochemical (IHC) assays were designed to identify intralesional tissue antigens of canine distemper virus (CDV), and canine adenovirus-1 (CAdV-1) and canine adenovirus-2 (CAdV-2). The most frequent histopathological patterns diagnosed were interstitial pneumonia (83.33%; 6/5) and hepatocellular vacuolar degeneration (50%; 3/6). IHC identified intralesional intracytoplasmic immunoreactivity to CDV antigens in all otters evaluated, with positive immunolabeling occurring within epithelial cells of the lungs, stomach, kidneys, and liver, and skin. Intracytoplasmic CAdV-2 antigens were identified within epithelial cells of the peribronchial glands in four otters with interstitial pneumonia. These findings resulted in singular and simultaneous infections in these neotropical otters, represented the first report of concomitant infections by CDV and CAdV-2 in free-living neotropical otters from the Southern Hemisphere, and suggested that this mammalian species is susceptible to infections by viral disease agents common to the domestic dogs and may develop similar histopathologic disease patterns.