Opossum Research Articles

Origin and distribution of the brachial plexus in red-necked wallaby (Notamacropus rufogriseus, Marsupialia: Macropodidae).

Notamacropus rufogriseus (red-necked wallaby) are in the family Macropodidae, which is the second largest family of marsupials after the family Didelphidae. This study was conducted with the aim of providing a detailed description of the origin and distribution of the brachial plexus in N. rufogriseus. Two-year-old male and 3-year-old female red-necked wallabies were used for the study. The brachial plexus was formed by ventral rami of C4, C5, C6, C7, C8, and T1 spinal nerves. It is composed of three trunks that give rise to 12 principal nerves. The cranial trunk is formed by the combination of the rami C4-C7; the middle trunk is formed by the combination of the rami C6 and C7; and the caudal trunk is formed by the combination of the rami C8 and T1. Differences between left and right side of the plexus brachialis were not observed. C6 ventral spinal rami contribute the most to brachial plexus nerve formation, while C4 contributes the least. The formation and distribution of the plexus in N. rufogriseus exhibited more resemblance to the patterns observed in marsupial animals rather than placental mammals. Marsupial mammals demonstrate the involvement of C4 in the development of the brachial plexus. The formation and branching of the brachial plexus sequentially adapt in accordance with changes in their thoracic limb activities and innervation points. Anatomical data from brachial plexus studies optimizes thoracic limb clinical and surgical treatments. This work can provide baseline data for future marsupial brachial plexus studies and fill gaps in the scarce literature.

Specificity of fleas associated with opossums in a landscape gradient in the Paranaense Rainforest Ecoregion.

The degree of host specificity of fleas varies from highly specific (monoxenous) to opportunistic (polyxenous). Specific parasite-host associations can be observed among some flea families and tribes and mammalian orders, such as fleas of the tribe Tritopsyllini (Ctenophthalmidae, Doratopsyllinae) and opossums (Didelphimorphia). Specimens of the family Didelphidae are common hosts of fleas of the genus Adoratopsylla (Ewing, 1925). In northern Argentina, Adoratopsylla (Adoratopsylla) antiquorum antiquorum (Rothschild, 1904) and Adoratopsylla (Tritopsylla) intermedia intermedia (Wagner, 1901) were recorded preferentially parasitizing opossums. In order to study parasite/host relationships, fleas were collected from opossums captured in different environments in the Paranaense Rainforest ecoregion, northern Misiones province between 2016 and 2018. A total of 287 fleas were collected from 110 opossums. The fleas were identified as Pulicidae: Ctenocephalides felis felis (Bouché, 1835); Rhopalopsyllidae: Polygenis (Polygenis) rimatus (Jordan, 1932), Polygenis (Polygenis) roberti roberti (Rothschild, 1905); Ctenophthalmidae: A. (T.) i. intermedia, A. (A.) a. antiquorum, Adoratopsylla (Adoratopsylla) antiquorum ronnai (Guimarães, 1954). We report for the first time in Argentina a male specimen of A. (A.) a. ronnai collected on Didelphis albiventris (Lund, 1840) (Didelphidae), and male and female specimens of P. (P.) r. roberti collected on Didelphis aurita (Wied-Neuwied, 1826), and we describe the expansion of the geographic and host distribution of fleas to the Paranaense Rainforest ecoregion. Our records reinforce the specific association between Adoratopsylla and Polygenis fleas and didelphid opossums, mentioned in the literature for the Atlantic Forest ecoregion in Brazil. Furthermore, we observed that flea communities in opossums change in a landscape gradient, with invasive cat fleas and euryxenous fleas common in anthropized areas, and endemic fleas common in natural areas. Our results underline the importance for public health and veterinary medicine the analysis of flea circulation between wild and urban environments due to the risk of pathogen transmission.

Ancestrally Reconstructed von Willebrand Factor Reveals Evidence for Trench Warfare Coevolution between Opossums and Pit Vipers.

Opossums in the tribe Didelphini are resistant to pit viper venoms and are hypothesized to be coevolving with venomous snakes. Specifically, a protein involved in blood clotting (von Willebrand factor [vWF] which is targeted by snake venom C-type lectins [CTLs]) has been found to undergo rapid adaptive evolution in Didelphini. Several unique amino acid changes in vWF could explain their resistance; however, experimental evidence that these changes disrupt binding to venom CTLs was lacking. Furthermore, without explicit testing of ancestral phenotypes to reveal the mode of evolution, the assertion that this system represents an example of coevolution rather than noncoevolutionary adaptation remains unsupported. Using expressed vWF proteins and purified venom CTLs, we quantified binding affinity for vWF proteins from all resistant taxa, their venom-sensitive relatives, and their ancestors. We show that CTL-resistant vWF is present in opossums outside clade Didelphini and likely across a wider swath of opossums (family Didelphidae) than previously thought. Ancestral reconstruction and in vitro testing of vWF phenotypes in a clade of rapidly evolving opossums reveal a pattern consistent with trench warfare coevolution between opossums and their venomous snake prey.

Mammal collections in Brazil

Advances in our knowledge on the planet biodiversity have been largely dependent upon biological collections, and today they continue to be the cornerstone of several disciplines. Recently, the Brazilian Society of Mammalogists established the Mammal Collections Committee (CCM-SBMz) aiming to collect, organize and share information on the mammalian collections in Brazil, as well as support their management. As a first step, our goal here is to provide a diagnosis of mammal collections in Brazil, and the CCM-SBMz contacted 100 collections and successfully registered 71, distributed in all five Brazilian regions. These collections house ca. 372,200 specimens, with 60% of these concentrated in three institutions: MNRJ, MZUSP, and MPEG. The material more commonly deposited are voucher specimens. The database is completely digitized or in process of digitization in most collections, however, this information is not widely available online. The geographic coverage of the collections is mainly regional or national. In number of specimens, Rodentia is the most frequent order in the collections, followed by Carnivora. At the family level, Didelphidae, Cricetidae, and Felidae are the more frequent taxa. This study shows that Brazil houses an important volume of mammalian specimens. However, considering the country’s continental size and high mammal diversity, these numbers are still far from a sufficient representation of the Brazilian mammalian diversity. The results summarize the first efforts of the CCM-SBMz and the committee will continue monitoring the mammal collections in Brazil, as well as working to help the management and growth of collections.

Taxonomic review of the slender mouse opossums of the "Parvidens" group from Brazil (Didelphimorphia: Didelphidae: Marmosops), with description of a new species.

The genus Marmosops comprises small marsupials of the family Didelphidae (≤ 200 g), widely distributed in a variety of lowland rainforest and montane forest habitats, extending from Panama to southern Bolivia and southeastern Brazil. The smallest species of the genus are included in the "Parvidens" group, which includes M. pakaraimae, M. parvidens and M. pinheiroi. Although the monophyly of this group and species relationships are well defined, molecular studies have indicated that M. pinheiroi may represent a species complex, which has never been tested based on morphological analysis. In this study, we present the taxonomic review of M. pinheiroi based on the largest sample ever analyzed of this species. The external and craniodental morphology of 613 specimens of M. parvidens and M. pinheiroi from the northern, eastern, central and southern Brazilian Amazonia and northern Cerrado were examined. Besides, 28 craniodental dimensions were measured from adult specimens to support univariate and multivariate statistical analyses. Our results corroborate the validity of M. parvidens and indicate that M. pinheiroi is a complex formed by three species - M. pinheiroi (s. s.), distributed to the north of the Amazon River, from eastern Venezuela to the state of Amapá in Brazil; M. woodalli, which occurs east of the Xingu river and in the Marajó Island, state of Pará, extending to the east in the states of Tocantins and Maranhão; and a new species that occurs from the left bank of the Madeira River to the left bank of the Xingu River, herein described. Although the great morphometric similarity, species of the M. pinheiroi complex tended to be more different from each other than to M. parvidens in both univariate and multivariate analyses. Morphologically, these species may be positively distinguished by unique combinations of characters, such as dorsal and ventral fur coloration, arrangement of gray based hairs on the venter, supraoccipital shape, development of anterior and posterior portions of the M3 stylar shelf, continuity or not between the preprotocrista and anterior labial cingulum along the anterior margin of the upper molars, development of the metaconule in the upper molars, and number of cusps of the m4 talonid. The present work provides new perspectives for studies based on molecular data in order to test the species hypotheses recognized here and evaluate to what extent the Tapajós, Madeira, and Araguaia-Tocantins rivers actually isolate Marmosops populations.

Relación de los pequeños mamíferos terrestres (Rodentia y Didelphimorphia) con la estructura de la vegetación en el Bosque Atlántico Interior – un análisis multivariado

The ecological importance of small mammals includes their role as dispersers of seeds, spores and propagules of plants, fungi and lichens, decomposers of organic matter and controllers of invertebrates as well as prey of a great number of vertebrates. The objective of this research was to determine the relationship between non-volant small mammals (Rodentia and Didelphimorphia) to vegetation structure and the extent of degradation of the forest in an area near the western boundary of the Upper Parana Atlantic Forest, and to evaluate seasonal and interannual variation in species’ abundances. The study was conducted in the Mbaracayu Forest Natural Reserve, Paraguay. Mark-capture methodology was employed in three sites with different degrees of degradation, in two seasons of the year (dry and rainy), in 2015 and 2016. A multivariate analysis was performed with ANOVA and MANOVA, evaluating degree of habitat disturbance and annual and seasonal variation as independent variables and species abundances as dependent variables. Sixteen small-mammal species were recorded, with 1,161 captures of 598 individuals and 563 recaptures throughout the sampling. Twelve species were of the Order Rodentia (all of the family Cricetidae, subfamily Sigmodontinae), and four of the Order Didelphimorphia (family Didelphidae). Variables that were significant for the most abundant species (Akodon montensis) were interannual variation and habitat degradation. The most common didelphid species in the study was Gracilinanus agilis, which appears well-adapted to different degrees of habitat degradation, given its occurrence in all sites. Plant communities, including their composition and degree of habitat disturbance, are important for small-mammal communities which are interacting in the different habitats of the forest. In this study we observed that Akodon montensis was most abundant in the habitat of moderate disturbance in the dry season (June). This habitat was characterized by large trees with grasses predominant in the understory. Hylaeamys megacephalus was most abundant in the dry season (June) and less so in the rainy season (November). Oligoryzomys nigripes is a habitat generalist and is less specialized in food preference. Abundance of the didelphid species Gracilinanus agilis was quite variable among sampling periods, but the species was present in all three levels of habitat degradation. The various species (especially the most abundant) exhibited different responses to habitat degradation and to interannual and seasonal variations.

Small mammals of the Estação Ecológica de Bananal, southeastern Atlantic Forest, Brazil, with description of a new species of Brucepattersonius (Rodentia, Sigmodontinae)

The Atlantic Forest harbors an impressive diversity of nonvolant small mammals. Despite having been the target of many ecological and taxonomical studies in the last decades, this group is still poorly known in several aspects – basic information on intrapopulational morphologic variation and proper diagnoses are lacking for many species, even for common taxa. This is related to the fact that large series of specimens from a single locality are extremely rare in scientific collections. A consistent sampling effort was conducted at Estação Ecológica de Bananal, northeastern São Paulo State, throughout seven field expeditions between 2003 and 2011, under the coordination of the Museu de Zoologia da Universidade de São Paulo, resulting in extensive series of nonvolant small mammals. We studied in detail the external and cranio-dental morphology of this sample (575 specimens), that we assigned to 31 known species besides one new species to science. Most species belong to order Rodentia (26 species) from the families Cricetidae (22 species) and Echimyidae (four species); the remaining (six species) are marsupials from the order Didelphimorphia, family Didelphidae. This is one of the most diverse assemblages ever recorded in this biome, and includes some of the rarest endemic rodents of the Atlantic Forest, such as Abrawayaomys ruschii, Blarinomys breviceps, Drymoreomys albimaculatus, Phaenomys ferrugineus, Phyllomys kerri and Rhagomys rufescens. This outstanding richness can be explained by the extensive sampling effort performed for a long period of time. Also, the capture success of the third expedition (8.25%) is among the highest rates obtained in the Atlantic Forest and the extensive use of pitfall traps was fundamental for trapping this high number of species. Herein, we provide an annotated list of nonvolant small mammals occurring at Estação Ecológica de Bananal, with comprehensive analyses of morphological variation and detailed diagnoses that will allow their proper identification, and will provide a sound basis for a better comprehension of the geographic variation of these taxa across the biome. We also present a formal description for a new species of Brucepattersonius from the mountain ranges along the Paraíba do Sul valley. For five species of sigmodontine rodents, we investigate the levels of ontogenetic and sexual variation, and while the first is accentuate in all analyzed species the second does not contribute significantly to intrapopulation variation.

Comparison of two protocols for field immobilization of white-eared opossums (Didelphis albiventris)

Fil: Waxman Dova, Samanta. Universidad de Buenos Aires. Facultad de Cs.veterinarias. Catedra de Anestesiologia y Algiologia; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Animal welfare aspects in the trade of (exotic) mammals on German animal fairs and pet markets

Several hundred animal fairs and pet markets annually take place in Germany . As part of the EXOPET-I-Study, we visited 17 animal fairs in 2016 to gain insight into the traded (exotic) mammal species. Furthermore, we assessed whether the accommodation of the mammals was compliant with the ‘Guidelines for Animal Fairs under Animal Welfare Aspects’ (Guidelines for Animal Fairs) issued by the Federal Ministry of Consumer Protection, Food and Agriculture in 2006. At the visited fairs, 25 mammal species were offered for sale. Among them were rarely kept (exotic) mammals such as forest African dormouse (Graphiurus murinus) or grey shorttailed opossum (Monodelphis domestica). At all fairs, we found animal welfare problems concerning feed and water supply, sufficiently sized cages, adequate litter, and retreat possibility. At only one animal fair, water was freely available for each animal in all cages. Adequate feed was missing in over 20 % of the cages at nine animal fairs. At 11 animal fairs, the required cage size did not comply with the Guidelines for Animal Fairs in over 60 % of the cages. Sturdy retreat possibilities were missing in over 60 % of the cages at 16 animal fairs. The Guidelines for Animal Fairs should be implemented more stringently at animal fairs to guarantee standardized procedures throughout Germany and improve animal welfare. A main objective here is to improve on-site quality control by competent authorities and by experts (e.g. specialized veterinarians) from veterinary inspection offices assisting the authorities during on-site welfare inspections.

Parotid Salivary Gland Basal Cell Adenocarcinoma in a Big-eared Opossum (Didelphis aurita)

The opossum (family Didelphidae) is a marsupial endemic to the Americas. Apart from the South American short-tailed opossum (Monodelphis domestica) and the Virginia opossum (Didelphis virginiana), there is considerable lack of knowledge about the health and diseases of most opossum species. Among these, the big-eared opossum (Didelphis aurita) is found in Argentina, Brazil and Paraguay. Natural and experimental studies have shown this species to be susceptible to infectious agents with zoonotic potential and the animals may play a role in transmission of such agents. However, neoplasia appears to be uncommon in this species. We describe the gross, microscopical and immunohistochemical features of a parotid salivary gland basal cell adenocarcinoma in a free-living big-eared opossum. This case represents the first report of salivary gland neoplasia in opossums.

Contrasting activity times and habitat use of Virginia opossums ( Didelphis virginiana ) and raccoons ( Procyon lotor ) in urban natural areas

Contrasting activity times and habitat use of Virginia opossums ( Didelphis virginiana ) and raccoons ( Procyon lotor ) in urban natural areas

Helmintos de la República de Costa Rica IV. Algunos Tremátodos de animales domésticos y silvestres

In this contribution seven forms of digenetic trematodes, some parasitic on cattle and some in wild animals, are described. Excepting Fasciola hepatica Linnaeus, 1758, whose presence in cattle and horses in Costa Rica has been cited by Chavarria in 1940, all the species considered are new to the helminthologic fauna of Costa Rica. Specimens of a paramphistomid found in Costa Rica catt1e have been classified as Paramphistomum cervi (Zeder, 1790) Fischoeder, 1901, in view of the presence of a genital sucker, the configuration of the digestive apparatus, and the structure and disposition of the reproductive organs and vitelline glands. Fasciola hepatica Linnaeus, 1758 is also a frequent parasite in Costa Rica, the precise life cycle of this parasite is unknown in the Republic but studies have been undertaken to determine its intermediate mollusean host. Choledocystus intermedius Caballero, Bravo and Cerecero, 1944 has been found for the first time in Costa Rica, in toads Bufo marinus marinus Linnaeus, 1758 thus allowing its range to be defined from southern Mexico to Panama. Gorgoderina megalorchis Bravo, 1948 is another species of trematode parasite of the amphibian host cited above; our specimens differ from those studied by M. Bravo Hollis only in size, the specimens from Costa Rica being larger than those from Mexican toads; the new locality record extends its geo­graphical distribution to Central America. Urotrema scabridum Braun, 1900 has been collected in Costa Rica for the first time, from the bat Eptesicus propinquus Peters which is also considered to be a new host record. Two species of the genus Rhapalias: R. coronatus (Rudolphi 1819) Stiles and Hassall, 1898 and R. horridus (Diesing, 1850) Stiles and Hassall, 1898 are registered from the Costa Rican opossum, Didelphis marsupialis etensi Allen; both species are known to parasitize various South American and Mexican marsupials and the Costa Rican specimens do not differ from these in structural or measurable details. Finally, the trematode Heronimus chelydrae Mac Callum, 1902 has been collected from the lungs of freshwater turtles of the genus Kinosternon. According to the studies of E. Caballero y C. 1940, it is believed that this is the only species in the genus; it has also been reported from turtles of Panama, Mexico and the United States in North America. It has been noted that an early regression of the testes occurs in this species, since these were persistent in only a few of the specimens described.

Presence of Virginia opossum (Didelphis virginiana) and Pic (Triatoma dimidiata) infected with Trypanosoma cruzi in urban areas: preliminary evaluation in the city of Campeche, Mexico

espanolRESUMEN: El objetivo del estudio fue identificar la prevalencia de infeccion con Trypanosoma cruzi en zarigueyas (Didelphis virginiana) y Pic (Triatoma dimidiata) capturados en areas urbanas de la ciudad de Campeche, Mexico. Se colectaron 25 zarigueyas con una prevalencia de infeccion con T. cruzi del 52% (13/25). Tambien se colectaron 36 vectores de Pic con una prevalencia de infeccion del 41,6% (15/36) con T. cruzi. Todos los aislados de T. cruzi fueron TcI de acuerdo con la predominancia de este linaje en Mexico independientemente del huesped mamifero o vector. EnglishABSTRACT: The aim of this study was to identify the infection prevalence of Trypanosoma cruzi in opossums and triatomines captured in urban areas of Campeche City, Mexico. We collected 25 specimens of marsupials of Virginia opossums (Didelphis virginiana) species showing a T. cruzi infection prevalence of 52% (13/25). Also, 36 specimens of Pic (Triatoma dimiata) vectors were collected, showing a T. cruzi infection prevalence of 41.6% (15/36). All T. cruzi isolates were TcI, which correspond to the predominant lineage in mammals of Mexico, irrespective of the mammalian host species or vector.

Estudo anatômico e radiográfico do crânio no gambá-de-orelha-branca (Didelphis albiventris)

This study was made to investigate the anatomical features of the white-eared opossum skull, by osteology and radiographic anatomy. For this, five animals were used without sexual distinction. The skull was examined by radiographic and macroscopic characteristics. The skulls were then subjected to maceration. The skull was described macroscopically according to standard views, i.e. dorsal and caudal, lateral, ventral, and midsagittal. The skull can be divided into facial (viscerocranium) and cranial (neurocranium) regions. The facial region was elongated and more developed than neurocranium. The supraorbital foramen was absent. The tympanic bulla is not well developed. The zygomatic arch was formed by zygomatic process of the temporal bone, zygomatic process of the maxilla, and temporal process of the zygomatic bone. There was no significant difference between bones found in this study when compared with those described for others mammals. These findings may contribute to the better understanding of the anatomy and biology of the white-eared opossum.

Morphological and ultrastructural analysis of the teeth of guaiquica (Gracilinanus microtarsus, Wagner, 1842)

Abstract Introduction: The guaiquica ( Gracilinanus microtarsus) is an omnivorous-frugivorous marsupial, which belongs to family Didelphidae and subfamily Didelphinae. By feeding on small fruits, it is a species of considerable ecological importance in seed dispersal of some plants. The teeth are calcified and have adapted anatomical structures, which exhibit morphological variation among vertebrates. They are important for the systematic and sometimes represent the only traces of extinct species, and may also assist the phylogenetic reconstruction of these species. Objective: In order to establish morphological patterns of the teeth of G. microtarsus, the establishment of dental formula of the species was performed. Materials and methods: We used macroscopic analysis, microstructural analysis by light microscopy and ultrastructural analysis by scanning electron microscopy in five G. microtarsus adults (n= 3 males and n= 2 females) were performed. Results and conclusion: We conclude that the dental formula of G. microtarsus (2x I 5/4 C1/1 P 3/3 M 4/4), totaling 50 teeth is similar to that described in opossum (Didelphis sp.). The teeth are classified as thecodont and bunodont and microscopic morphology of teeth is also similar to Didelphis sp. and other species that have braquidonts teeth.

Opossums caught acting surprisingly social

Opossums caught acting surprisingly social

Taxonomic status and phylogenetic relationships ofMarmosa agilis peruana Tate, 1931 (Didelphimorphia: Didelphidae), with comments on the morphological variation ofGracilinanusfrom central-western Brazil

The marsupials of the family Didelphidae went through profound taxonomic rearrangements in recent decades, mainly related to an increase in the number of specimens deposited in scientific collections and the inclusion of molecular data in systematic analyses, resulting in better resolved phylogenies and taxa delimitation. Analyses of a large series of the gracile mouse opossum Gracilinanus agilis, including types and complementary material, recovered specimens assignable to Marmosa agilis peruana Tate, 1931 as a monophyletic group that is diagnosable by unique morphological, morphometric and molecular datasets, meriting its recognition as a full species. Here we provide an emended diagnosis, description and comparisons with congeners for G. peruanus. The former species differs from the latter by the dull reddish dorsal pelage, smaller general size, position of the maxillary fenestrae, presence of accessory cusps in upper canines, and morphology of the alisphenoid tympanic process. It ranges from central Peru to central Bolivia and western Brazil in the states of Rondonia and northwestern Mato Grosso, where it occurs in sympatry with G. agilis. Many collecting localities lie in areas with high diversity of non-volant small mammals and accelerated deforestation processes, highlighting its importance in terms of biogeographic studies and conservation policies. © 2014 The Linnean Society of London

Mating behavior of the Mexican mouse opposum (<i>Marmosa canescens</i>) in Cuixmala, Jalisco, Mexico.

Comportamiento de apareamiento del raton mexicano oposum ( Marmosa canescens ) en Cuixmala, Jalisco, Mexico.

Variations of chromosomal structures in Caluromys philander (Didelphimorphia: Didelphidae) from the Amazon region

Caluromys is considered to be one of the most ancient genera of extant marsupials and is positioned among the basal taxa of the family Didelphidae. At least two species occur in Brazil, C. philander and C. lanatus, both of which have 2n=14 chromosomes. For the first time, we present evidence of an intrapopulation polymorphism of the sexual chromosome pair in C. philander females from the Central Amazon region. Detailed cytogenetic results of animals from three localities on the Amazon region were analyzed using classical cytogenetics (NOR, C-Band and G-Band) and molecular techniques (18S rDNA and telomere probes). Similar to other conspecific individuals, the diploid number of these animals is 2n=14, and their fundamental number is 24, with NOR present on the 6th autosomal pair. The X chromosome presented variation detectable by G banding, suggesting a pericentric inversion.

Summer food habits of the Patagonian opossum, Lestodelphys halli (Thomas, 1921), in southern arid Patagonian shrub-steppes

Estudiamos la dieta estival de la comadrejita patagonica Lestodelphys halli en el sureste de la Patagonia Argentina, por medio del analisis de contenidos estomacales provenientes de animales muertos y de fecas. Encontramos una gran variedad de invertebrados (87,2% de frecuencia de ocurrencia) seguido de aves y reptiles (10,64%) tanto en estomagos como en fecas. Los frutos fueron escasos en la dieta. En cautividad, la comadrejita patagonica se alimenta fundamentalmente de roedores, reptiles, aves e invertebrados. Sin embargo, no encontramos restos de roedores en la dieta de la comadrejita. Sugerimos que la comadrejita patagonica no es un predador eficiente de roedores en estado silvestre. El alto consumo de invertebrados, reptiles, aves y frutos durante el verano, cuando estos items son abundantes, refleja el comportamiento oportunista de esta especie.