Dromiciops Research Articles

The effects of poly-unsaturated fatty acids on the physiology of hibernation in a South American marsupial, Dromiciops gliroides

Many mammals hibernate, which is a profound lethargic state of several weeks or months during winter, that represents a transitory episode of hetherothermy. As with other cases of dormancy, the main benefit of hibernation seems to be energy saving. However, the depth and duration of torpor can be experimentally modified by the composition of food, especially by fattyacid composition. In eutherians, diets rich in unsaturated fatty acids (i.e., fatty acids with at least one double bond) lengthen torpor, reduce metabolism and permit hibernation at lower temperatures. Here we studied whether diets varying in fatty acid composition have an effect on the physiology of hibernation in a South American marsupial, Dromiciops gliroides. We designed a factorial experiment where thermal acclimation (two levels: natural versus constant temperature) was combined with diet acclimation: saturated (i.e., diets with high concentration of saturated fatty acids) versus unsaturated (i.e., diets with high concentration of unsaturated fatty acids). We measured energy metabolism in active and torpid individuals, as well as torpor duration, and a suite of 12 blood biochemical parameters. After a cafeteria test, we found that D. gliroides did not show any preference for a given diet. Also, we did not find effects of diet on body temperature during torpor, or its duration. However, saturated diets, combined with high temperatures provoked a disproportionate increase in fat utilization, leading to body mass reduction. Those animals were more active, and metabolized more fats than those fed with a high proportion of unsaturated fatty acids (=“unsaturated diets”). These results contrast with previous studies, which showed a significant effect of fatty acid composition of diets on food preferences and torpor patterns in mammals.

How forest marsupials are affected by habitat degradation and fragmentation? A meta-analysis.

Habitat fragmentation and degradation are important biodiversity change drivers worldwide. Their effects have been described for many animal groups, but little is known about marsupials. We conducted a meta-analysis aiming to evaluate the actual effects of habitat fragmentation and degradation on forest marsupials. From a literature survey, we obtained 85 case studies reporting disturbance comparisons. We found a negative overall effect, as well as a negative effect for habitat fragmentation, but not for habitat degradation. Marsupials from Oceania were negatively affected by habitat disturbance, whereas there was no effect for those from South America. Arboreal marsupials were negatively affected, whereas terrestrial marsupials did not. Species from the families Dasyuridae (Antechinus spp.) and Microbiotheriidae (Dromiciops gliroides) showed to be sensitive to habitat disturbance.

Profound changes in blood parameters during torpor in a South American marsupial

Seasonal torpor or hibernation is a phenomenon characterized by a physiological transition to dormancy (torpor) during challenging periods in terms of energy availability or metabolic load. Extensive physiological reprogramming and changes in gene-expression, immune function, oxygen transport and intermediate metabolism, occur during eutherian hibernation. Here we studied the seasonality of blood parameters, and during daily torpor, in a South American marsupial (Dromiciops gliroides). Seasonal trends in blood parameters showed an increase in hematological parameters during winter, and increases in total proteins, albumin and globulin during autumn. In contrast, torpor induced a drastic drop during most blood parameters. PCV dropped significantly 60%, as well as RBC (58%), hemoglobin concentration (58%), WBC (79%), including neutrophils (51%), eosinophils (84%) and lymphocytes (82%). Biochemical parameters also showed reductions: triglycerides (81%), proteins (32%), albumin (24%), globulins (38%), albumin (24%), creatinine (48%) and glucose (42%). Our results confirm some patterns observed in hibernating eutherians, such as leukopenia, probably caused by sequestration of white blood cells in organs. However, red blood cells and hemoglobin concentration also were reduced, which is to the best of our knowledge has not been reported for marsupials. The observed reduction in biochemical parameters suggests that marsupials, as in eutherians, change from carbohydrate-based to lipid-based metabolism during hibernation. However, the absence of increases in beta-hydroxybutyrate is puzzling. Finally, we found an increase (although non-significant after statistical correction for multiple comparisons) of creatine kinase which together with an increase in neutrophil/lymphocyte ratio could be indicative of muscle lysis and inflammation. These results indicate profound changes in standard physiological processes during torpor.

Philodryas chamissonis (Reptilia: Squamata: Colubridae) preys on the arboreal marsupial Dromiciops gliroides (Mammalia: Microbiotheria: Microbiotheriidae)

Philodryas chamissonis, the Chilean long-tailed snake, is a diurnal predator mainly of Liolaemus lizards, but also of amphibians, birds, rodents and juvenile rabbits. Dromiciops gliroides (Colocolo opossum) is an arboreal marsupial endemic of temperate rainforest of southern South America. Little information is available about this marsupial's biology and ecology. Here we report the predation of one Colocolo opossum by an adult female P. chamissonis in a mixed Nothofagus forest, composed mainly by N. dombeyi, N. glauca and N. alpina trees, in the "Huemules de Niblinto" National Reserve, Nevados de Chillán, Chile. Since these two species have different activity and habitat use patterns, we discuss how this encounter may have occurred. Although it could just have been an opportunistic event, this finding provides insights into the different components of food chains in forest ecosystems of Chile.

Aerobic power, huddling and the efficiency of torpor in the South American marsupial, Dromiciops gliroides

SummaryDuring periods of cold, small endotherms depend on a continuous supply of food and energy to maintain euthermic body temperature (Tb), which can be challenging if food is limited. In these conditions, energy-saving strategies are critical to reduce the energetic requirements for survival. Mammals from temperate regions show a wide arrange of such strategies, including torpor and huddling. Here we provide a quantitative description of thermoregulatory capacities and energy-saving strategies in Dromiciops gliroides, a Microbiotherid marsupial inhabiting temperate rain forests. Unlike many mammals from temperate regions, preliminary studies have suggested that this species has low capacity for control and regulation of body temperature, but there is still an incomplete picture of its bioenergetics. In order to more fully understand the physiological capacities of this “living fossil”, we measured its scope of aerobic power and the interaction between huddling and torpor. Specifically, we evaluated: (1) the relation between basal (BMR) and maximum metabolic rate (MMR), and (2) the role of huddling on the characteristics of torpor at different temperatures. We found that BMR and MMR were above the expected values for marsupials and the factorial aerobic scope (from CO2) was 6.0±0.45 (using CO2) and 6.2±0.23 (using O2), an unusually low value for mammals. Also, repeatability of physiological variables was non-significant, as in previous studies, suggesting poor time-consistency of energy metabolism. Comparisons of energy expenditure and body temperature (using attached data-loggers) between grouped and isolated individuals showed that at 20°C both average resting metabolic rate and body temperature were higher in groups, essentially because animals remained non-torpid. At 10°C, however, all individuals became torpid and no differences were observed between grouped and isolated individuals. In summary, our study suggests that the main response of Dromiciops gliroides to low ambient temperature is reduced body temperature and torpor, irrespective of huddling. Low aerobic power and low time-consistency of most thermoregulatory traits of Dromiciops gliroides support the idea of poor thermoregulatory abilities in this species.

Ecological consistency across space: a synthesis of the ecological aspects of Dromiciops gliroides in Argentina and Chile

Dromiciops gliroides is an arboreal marsupial found in the temperate forests of South America (36-43 °S). This species is the sole extant representative of the order Microbiotheria, and is a key seed disperser of many native plant species, including the keystone mistletoe Tristerix corymbosus. Here, we synthesized the current knowledge on the ecological aspects of this species, and compared the available information from Argentina and Chile. Population density (23 ± 2 (mean ± SE) individual/ha) and home range (1.6 ± 0.6ha) appear to be relatively similar across a marked ecological gradient in the mainland, but lower densities (7 ± 2 individual/ha) and smaller home ranges (0.26 ± 0.04ha) were detected at island sites. We detected regional variation in body condition in Chile, but there were no significant differences across a wider E-W gradient. Movement patterns fit a random walk model; such behavior might have important consequences in shaping plant's spatial patterns. Although our data suggest that D. gliroides is more tolerant to habitat disturbance than previously thought, its incapability to disperse across non-forested areas suggests that the rapid rate of habitat loss and fragmentation that characterizes southern temperate forests likely poses a serious threat to this species. These ecological similarities are surprising given that forests studied receive dramatically different rainfall and correspond to distinct forest types. The evidence synthetized here dispels some of the myths about this species but also stresses the need for more comprehensive ecological studies across its distribution range.

Evaporative water loss, relative water economy and evaporative partitioning of a heterothermic marsupial, the monito del monte (Dromiciops gliroides)

We examine here evaporative water loss, economy and partitioning at ambient temperatures from 14 to 33°C for the monito del monte (Dromiciops gliroides), a microbiotheriid marsupial found only in temperate rainforests of Chile. The monito's standard evaporative water loss (2.58 mg g(-1) h(-1) at 30°C) was typical for a marsupial of its body mass and phylogenetic position. Evaporative water loss was independent of air temperature below thermoneutrality, but enhanced evaporative water loss and hyperthermia were the primary thermal responses above the thermoneutral zone. Non-invasive partitioning of total evaporative water loss indicated that respiratory loss accounted for 59-77% of the total, with no change in respiratory loss with ambient temperature, but a small change in cutaneous loss below thermoneutrality and an increase in cutaneous loss in and above thermoneutrality. Relative water economy (metabolic water production/evaporative water loss) increased at low ambient temperatures, with a point of relative water economy of 15.4°C. Thermolability had little effect on relative water economy, but conferred substantial energy savings at low ambient temperatures. Torpor reduced total evaporative water loss to as little as 21% of normothermic values, but relative water economy during torpor was poor even at low ambient temperatures because of the relatively greater reduction in metabolic water production than in evaporative water loss. The poor water economy of the monito during torpor suggests that negative water balance may explain why hibernators periodically arouse to normothermia, to obtain water by drinking or via an improved water economy.

Absence of mammary development in maleDromiciops gliroides: another link to the Australian marsupial fauna

The South American microbiotherian marsupial Dromiciops gliroides is regarded as a sister taxon to the monophyletic Australasian marsupial clade. Mammary anlagen have been documented in male American marsupials but have not been observed in males of any Australian marsupials. The aim of this study was to determine if mammary anlagen were present in developing pouch young (PY) of Dromiciops. The developmental anatomy, particularly the presence of mammary anlagen, was investigated in 3 neonatal male (n 5 2) and female (n 5 1) Dromiciops PY (,15–20 days postpartum). External and internal structures were examined to confirm PY gender and to provide basic information on development, particularly of the genitourinary system. In the female PY early pouch development was observed as well as 4 clearly defined abdominal mammary anlagen. No external teat or mammary anlagen development was seen in the 2 male PY and serial sections from the external genitalia to upper thorax failed to reveal any histological structures similar to mammary anlagen seen in the female. Absence of mammary anlagen in male Dromiciops PY provides further evidence that Dromiciops shares a closer relationship with the Australasian marsupial clade than with the American marsupial fauna.

Chaenothecopsis quintralis, a new species of calicioid fungus

Chaenothecopsis quintralis from southwestern Argentina is described and illustrated as a new species in the family Mycocaliciaceae. It has been found in three localities in the Andean Patagonian temperate forests, growing strictly on dung of an endemic marsupial Dromiciops gliroides. The new species is distinguished by the hemispherical, black capitulum of ascoma, the presence of asci with croziers, one-celled brown ascospores, and its fimicolous habitat. Analysis of partial nuclear large subunit rDNA (LSU) sequences showed that this taxon is within Mycocaliciales.

Description of a new species of Haemogamasus (Mesostigmata, Laelapidae, Haemogamasinae) from Chubut, Río Negro and Neuquén Provinces, Argentina

A new species of Haemogamasus mites is described from Chubut, Neuquén and Río Negro Provinces, Argentina. It was collected primarily from rodents of the genus Abrothrix (65 of 77 collections): Abrothrix longipilis (63), Abrothrix olivaceus olivaceus (1) and Abrothrix olivaceus xanthorhinus (1). Additional collections were made from Geoxus valdivianus (5) and Loxdomtomys micropus (5). Possibly incidental or contaminate collections were recorded from Oligoryzomys longicaudatus (1) and Dromiciops gliroides (1). Most collections came from Río Negro Province (36), with 22 from Neuquén and 19 from Chubut. An identification key is provided to distinguish ♀s of this new species from ♀s of species from the western hemisphere, based on morphological characters.

Population abundance, natural history, and habitat use by the arboreal marsupialDromiciops gliroidesin rural Chiloé Island, Chile

Populations of the endemic and threatened marsupial Dromiciops gliroides were studied in logged and unlogged forest patches and shrublands in a rural area of northern ChiloeI sland (42uS), Chile. We expected to find differences in abundance, with higher densities in unlogged, old-growth remnant forests. Individuals were livetrapped over 4 years (2005-2009) at the peak of their breeding (November) and nonbreeding (February) seasons. We estimated population densities using capture-mark-recapture procedures. Home range, diet (through fecal content), and health status (ectoparasite loads) were assessed for captured individuals. We estimated the length of the breeding season by the levels of reproductive hormones, whereas winter torpor was documented using artificial nest boxes. Population densities varied seasonally in accordance with breeding, with higher densities recorded during summer, and were similar in old-growth and in logged forests, but were considerable higher in forests than in shrublands. D. gliroides reproduced well in both unlogged and logged forests. Social torpor was documented for the 1st time and was fairly frequent (64%), especially among juveniles. Home ranges were 2 times larger for males than for females. We confirmed the omnivorous diet of D. gliroides, with predominant consumption of arthropods, and a higher consumption of fleshy fruits during summer. Habitat and animal age had significant effects on ectoparasite prevalence, with higher incidences among juveniles in logged forests. We conclude that D. gliroides is not a rare species in remnant forests in the rural landscape of ChiloeIsland. This result is crucial for the assessment of its conservation status and offers clues for designing better conservation strategies for this living fossil in anthropogenic landscapes.

Influence of habitat factors on the distribution and abundance of a marsupial seed disperser

Abstract Understanding factors that influence the distribution and abundance of seed dispersers is important because of the role these species play in maintaining plant communities. The temperate forest of Patagonia has an unusually high frequency of mutualisms, including obligate seed dispersal of a keystone mistletoe (Tristerix corymbosus) by the marsupial Dromiciops gliroides. We examined whether the distribution and abundance of D. gliroides was related to the distribution and abundance of this mistletoe, which is a principal food source, or alternatively, whether other habitat features constrain the distribution and abundance of this marsupial. We conducted field surveys for D. gliroides, mistletoe, and other habitat variables and developed a set of habitat models in which model variables were defined a priori. We found that the distribution of D. gliroides was related to bamboo cover. Bamboo is an important source of nest material and nest sites. However, when the minimum requirement for bamboo cove...

Relationships of South American marsupials (Didelphimorphia, Microbiotheria and Paucituberculata) and hard ticks (Acari: Ixodidae) with distribution of four species of Ixodes

Historical information shows that South American marsupials are irrelevant hosts for South American hard ticks (Ixodidae Murray) of the genera Haemaphysalis Koch, Rhipicephalus Koch and Dermacentor Koch. Twenty two Amblyomma Koch species were occasionally found on Didelphimorphia Gill, but some records are doubtful (i.e., A. dissimile Koch, 1844) and only A. fuscum Neumann, 1907 appears to be a relevant parasite of this type of host. Twelve species of Ixodes Latreille were determined on these hosts, although one of them, I. longiscutatus Boero, 1944, is probably misidentified. Four species, I. amarali Fonseca, 1935b, I. loricatus Neumann, 1899, I. luciae Sénevet, 1940 and I. venezuelensis Kohls, 1953 are usual parasites of Didelphimorphia. These species (I. venezuelensis excluded) have adult ticks feeding mostly on Didelphidae Gray, and sub-adult ticks feeding mostly on Didelphidae and several species of sigmodontine rodents. All parasitic stages of I. venezuelensis were recorded from Didelphimorphia although rodents are also of importance for its life cycle. Records from marsupials and nonmarsupial hosts show that I. amarali is established in eastern Brazil, and I. venezuelensis in Venezuela, Colombia, Panama and Costa Rica. The alleged southernmost record of I. luciae in Central Argentina was found to be erroneous and its southern limit is located in northwestern Argentina and its way northwards includes Bolivia, Peru, western Brazil, French Guiana, Surinam, Trinidad & Tobago, Panama, Guatemala, Belize and southern Mexico with unconfirmed but probably valid records for Ecuador, Colombia, Costa Rica, Nicaragua and Honduras. The distribution of I. loricatus has been historically considered to range from southern Argentina to southern Mexico but southernmost and northernmost records are now considered doubtful along with Venezuelan populations for this tick, while the only records for Panama and Colombia were based on wrong tick identifications. Bona fide populations of I. loricatus range from central-eastern Argentina and southern Uruguay to Paraguay up to north-eastern Brazil. Dromiciops gliroides Thomas, the only member of Microbiotheria Ameghino is the exclusive host of Ixodes neuquenensis Ringuelet, 1947. There is only one record of tick infestation (Ixodes jonesae Kohls, Sonenshine & Clifford, 1969) of Paucituberculata Ameghino, indicating that these marsupials are of no apparent importance for maintenance of South American hard ticks. We speculate that the species of Ixodes feeding on Didelphimorphia and Sigmodontinae Wagner are a clade derived from ancestors feeding exclusively on Didelphidae that radiated after the invasion of South America by Sigmodontinae or their ancestors. Ixodes neuquenensis (established in south-western South America) is considered a relatively new species that radiated from Ixodes parasites of Sigmodontinae invaders in southern South America.

Communal nesting, activity patterns, and population characteristics in the near-threatened monito del monte, Dromiciops gliroides

The “living fossil,” Dromiciops gliroides (monito del monte), is an endemic marsupial inhabiting the temperate rain forests of South America. It is cavity-dependent and faces high energetic costs associated with thermoregulation during the austral winter. Although D. gliroides is well known for seed dispersal in temperate rain forests, its ecology, behavior, and long-term population dynamics have received little attention. We monitored a population of D. gliroides and studied variation in abundance and density and seasonal changes in body mass and body condition index (BCI). In addition, we monitored activity and communal nesting with camera traps and nest boxes, respectively. Over 4 years we documented a mean population density of 26 (95% confidence interval = 19–32) individuals/ha. We found significantly greater body mass and BCI for females than for males, suggesting different energetic strategies during the prehibernation period. Animals were nocturnal and active until dawn. Communal nesting occurred during summer and early fall, but torpor by single individuals and small groups was increasingly frequent during winter. Communal nesting could be a key behavioral strategy affecting survival. However, given the greater frequency in warm seasons and groups composed of postreproductive females and juveniles, communal nesting might be more related to parental care associated with kin selection than to thermoregulation.

Rodents of the subfamily Sigmodontinae (Myomorpha: Cricetidae) as hosts for South American hard ticks (Acari: Ixodidae) with hypotheses on life history

Historical information shows that Sigmodontinae are irrelevant hosts for South American ticks of the genera Haemaphysalis Koch, Rhipicephalus Koch and Dermacentor Koch. Nine Amblyomma Koch species were found on Sigmodontinae but only Amblyomma triste Koch, 1844 appears strongly related to them. Eighteen species of Ixodes Latreille were determined on these hosts. Four species sporadically infest Sigmodontinae; eight are found mostly on Sigmodontinae but the records are too few for any inference. Six: I. amarali Fonseca, 1935, I. longiscutatus Boero, 1944, I. loricatus Neumann, 1899, I. luciae Sénevet, 1940, Ixodes sigelos Keirans, Clifford and Corwin, 1976 and I. venezuelensis Kohls, 1953 are usual parasites of Sigmodontinae. It is proposed that the Ixodes-Sigmodontinae relationship evolved from a South American tick ancestor parasite of Didelphidae. Their descendants are two extant clades, one formed by I. loricatus-I. luciae defined by analysis of 16S rDNA sequences further including I. amarali and I. schulzei by morphological affinities. These species (I. schulzei excluded) have adult ticks feeding on Didelphidae and sub-adult ticks feeding on Didelphidae and several species from five sigmodontin tribes. The second clade is formed by I. abrocomae Lahille, 1916 (known from few specimens, mostly collected from Sigmodontinae), I. sigelos (mainly a parasite of Sigmodontinae), I. stilesi Neumann, 1911 (parasite of deer), and possibly I. taglei Kohls, 1969 (parasite of deer) by morphological affinity. This clade is related to I. neuquenensis Ringuelet, 1947, an exclusive parasite of Dromiciops gliroides Thomas (Microbiotheriidae Ameghino).

Environmental and ecological architects: Guidelines for the Chilean temperate rainforest management derived from the monito del monte (Dromiciops gliroides) conservation

El cambio de uso de la tierra es una de las principales amenazas a la biodiversidad. Habitats naturales como el bosque templado lluvioso de Sudamerica han sido degradados, fragmentados y eliminados rapidamente. En consecuencia, es prioritario el manejo y conservacion de los remanentes, para lo que es necesario contar con una politica ambiental acorde. Las acciones de conservacion referentes al bosque lluvioso templado se han abordado mayormente desde una perspectiva de especies individuales, con poco enfasis en la conservacion a nivel de ecosistema. Mas aun, la informacion generada en este ambito tampoco ha permeado en el desarrollo de politicas ambientales. Utilizamos el estudio de caso del monito del monte (Dromiciops gliroides) para ilustrar como el conocimiento actual en ecologia y conservacion de una especie puede ser utilizado para generar una nueva politica ambiental. Dromiciops gliroides es una especie dependiente del bosque, con un importante rol ecologico y un gran interes evolutivo y de conservacion. Para garantizar su persistencia, proponemos dos componentes de gestion del habitat, a incorporarse en los planes de manejo: la estructura y la conectividad. La estructura hace referencia al arreglo espacial y la presencia de elementos estructurales clave que influyen en la calidad del habitat, mientras que conectividad se refiere a la conectividad funcional del paisaje. Conservando al monito del monte, se conservarian tambien otras especies dependientes del bosque y asi las interacciones ecologicas y los procesos ecoevolutivos, que determinan finalmente la conservacion del bosque lluvioso templado.

Bioenergetics and intestinal phenotypic flexibility in the microbiotherid marsupial (Dromiciops gliroides) from the temperate forest in South America

The microbiotherid marsupial Dromiciops gliroides inhabits the temperate forests of the Southern hemisphere, facing seasonal nutritional and energetic bottlenecks due to its apparently facultative insectivory/frugivory. In order to understand the physiological processes behind this ecological pattern, we studied the morpho-physiological changes that D. gliroides exhibits after dietary acclimation, in a sample of 21 wild-caught individuals fed over 1month with ad libitum diet of: (1) fruit, (2) insects or (3) a mix of insects and fruit. In addition, we measured oxygen consumption (VO2) at resting conditions. We also performed enzyme assays (sucrase, maltase, trehalase and aminopeptidase N) and measurements of organ morphology. We found that D. gliroides cannot fulfil its nutrient requirements only from insects or fruit. It needs a mixed diet in order to maintain its body mass and energy balance. However, as a response of diet acclimation, individuals showed several-fold changes in the activities of aminopeptidase-N, maltase and sucrase (but not trehalase). This result, both the magnitude of change and the simultaneous effects on three enzymes suggests that D. gliroides could exhibit adaptive phenotypic plasticity in the activity of intestinal enzymes. This study suggests also that D. gliroides, the only living representative of the Microbiotheria order, exhibits physiological adaptations to a generalist diet.

Legítima dispersión de semillas Ugni molinae Turcz. (Myrtaceae), por monito del monte, Dromiciops gliroides

We investigated if the marsupial Dromiciops gliroides (Microbiotheriidae) is a legitimate seed disperser of Ugni molinae (Myrtaceae). We compared the germination rate of defecated and not-defecated seeds. The results show that defecated seeds are viable and show a high germination rate than no-defecated seeds. We conclude that D. gliroides is a legitimate seed disperser of U. molinae, and it may affect their reproductive success. These results are the first evidence of a seed disperser for U. molinae, and also support the proposal that D. gliroides have an important role as a seed disperser in the temperate forest of southern South America.

Acari, Laelapidae (ectoparasitic mites), central and southern Chile

Laelapidae mites include ectoparasites of small mammals. The fauna of mites of many Neotropical areas is still understudied, and such is the case of Chile. We report the results of a survey carried out in central and southern Chile: Acanthochela chilensis Ewing 1933 is reported from Dromiciops gliroides Thomas 1894; Lukoschus maresi Radovsky and Gettinger 1999 from Abrothrix olivaceus (Waterhouse 1837); Laelaps echidninus Berlese 1887 from Rattus rattus (Linnaeus 1758) and R. norvergicus (Berkenhout 1769); and Gigantolaelaps wolffsohni (Oudemans 1910) and Mysolaelaps microspinosus Fonseca 1936 from Oligoryzomys longicaudatus (Bennett 1832). The association of Abrothrix sanborni Osgood 1943 with G. wolffsohni and M. microspinosus was accidental, since these mites are common ectoparasites of oryzomine rodents (Rodentia, Cricetidae, Sigmodontinae). Laelaps maresi, L. echidninus and M. microspinosus are reported for the first time for Chile. The results of this study increase the number of ectoparasitic laelapid mites known from Chile to five species.

Geographic distribution and historical occurrence ofDromiciops gliroidesThomas (Metatheria: Microbiotheria)

Occurrence records represent the key to understanding species distribution patterns. I analyzed the historical and geographical occurrence of Dromiciops gliroides, a marsupial endemic to the temperate rain forests of southern Chile and Argentina and the sole living representative of the order Microbiotheria. Eighty-eight localities spanning 7°31′ latitude (∼850 km) and 3°13′ longitude (∼350 km) are known for the species and were taken from previous works and museum specimens and integrated in a geographic information system. Species distribution was analyzed in a historical, geographic, and biogeographic context, with the use of maps at different scales (region, subregion, province, ecoregion, and forest type). The software MaxEnt was used to generate 2 potential distribution models with environmental data. Generated models show a northern contraction and southern expansion in the species’ potential distribution, with variation in habitat suitability throughout the current species range. Precipitation and some temperature-related variables influenced both generated models. The species’ occurrence lies within the Andean region; Subantarctic and Patagonia subregions; and Maule, Valdivian, and Subandean Patagonia provinces. At a smaller scale, most of the localities occur within the Valdivian Temperate Forests ecoregion, and in the majority of the forest types described for it, implying broader ecological requirements than expected. Identification of critical areas through potential distribution modeling may have implications on species conservation and biogeographic patterns.