Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Neomicroxus, a recently named genus, comprises small-bodied cricetid rodents patchily distributed in high-Andean ranges from Ecuador to Venezuela. Currently, two species of Neomicroxus are recognized, N. bogotensis, endemic to the Cordillera Oriental in Colombia and Cordillera de Mérida and Páramo de Tamá in Venezuela, and N. latebricola that occurs northern Andes of Ecuador. The genus is among the most poorly understood Neotropical rodents and to date no formal assessment about its alpha taxonomy was conducted. Based on DNA evidence of the first portion of the mitochondrial cytochrome b gene (cytb) and the first exon of the interphotoreceptor retinoid binding protein (IRBP), as well as craniodental measurements, we explored the divergence degree, genetic structure and phyletic relationships of the two species currently allocated under Neomicroxus. Our analyses support the monophyly of the genus as well as its uncertain tribal affiliation. Neomicroxus was retrieved as structured in two main branches, in agreement with the traditional recognition of two species. The populations referred to N. bogotensis exhibit deep divergence values (> 6 %) pointing to the existence of undescribed species under its concept. In contrast, populations of N. latebricola show a shallow genetic structure although implying recognizable geographical breaks. A moderate degree of genetic and morphological differentiation supports a new subspecies for the western populations of N. latebricola. Our contribution is the first attempt to better understanding the alpha taxonomy of Neomicroxus, highlighting the importance of the geographic complexity as a barrier to the genetic flow in N. bogotensis and the significance of the subspecies concept to formalize the geographic variation recovered in N. latebricola

The feeding habits of jaguar (Panthera onca) and puma (Puma concolor) were studied in the lower Tuichi, Hondo (PNANMI Madidi) and Quiquibey (RB Pilón Lajas) river valleys. A total of 122 large felid scats were collected and identified by an experienced local guide, with identifications later confirmed by morphometry. Of this total, 54 were also identified using associated tracks. For jaguar, prey species richness was 25 species considering all scats and 20 species only considering those scats associated with tracks. For puma, 28 and 22 prey species were obtained, respectively. The results indicate that there is low trophic niche overlap between both cats (0.46 and 0.44 respectively). The breadth of the trophic niche indicates that the jaguar is more specialized in its diet (0.28 and 0.42 respectively), mainly due to the high consumption of the white-lipped peccary (Tayassu pecari), which contributes significantly to jaguar prey biomass. The puma has a more generalist tendency (0.56 and 0.58 respectively), with the spotted paca (Cuniculus paca) the most frequently consumed prey and also contributing the most biomass. Despite the fact that both felines share most of their prey, jaguar and puma differ in the frequency of prey consumption.

The current issue of Therya includes a number of papers honoring the legacy and notable contributions of Dr. Sydney Anderson (1927-2018) to Bolivian and Neotropical mammalogy.   “El Doc,” as he was warmly referred to by hordes of Bolivians scientists and students, played a central role in the coming of age of mammalogy in Bolivia.  He influenced many aspects of this development, from using his own personal funds to purchase traps and museum cases for the then mammal collection of the Bolivian Museum of Natural History, to serving as a towering example of an unassuming mammalogist who loved and honored his science so much that he enjoyed going out camping and trapping in remote areas of Bolivia for almost three decades from 1964 to 1992, and until he was well into his late 60s.

The genus Spalacopus includes only one species, S. cyanus, endemic to central Chile and one of the species best adapted to a subterranean lifetyle in the family Octodontidae.  It is a member of the lineage consisting in Octodontomys as a sister clade containing Octodon and of a clade represented by Spalacopus and Aconaemys.  Although the external and cranio-dental morphology have been well studied, little is known of the postcranial morphology of S. cyanus.  Because of the peculiarities of its lifestyle and locomotion among the members of the family, it is interesting to characterize details of the morphology of the postcranial skeleton of this species and to infer their functional aspects of the morphology.  Twenty-nine specimens with postcranial material stored in two collections were studied: Museo de La Plata (MLP), La Plata, Buenos Aires, Argentina and Colección de Mamíferos del Instituto de Ciencias Ambientales y Evolutivas (UACH), Universidad Austral de Chile, Valdivia, Chile.  To describe in detail the morphology of the bone elements, the skeleton was divided in the following regions: axial skeleton, scapular girdle and forelimb, and pelvis girdle and hindlimb.  The structures included in the axial skeleton were mainly described in cranial-caudal orientation and the limbs in proximal-distal orientation.  All structures were observed with stereoscopic microscopes Leica Wild M3Z and Nikon SMZ 745T including pictures to illustrate the descriptions.  Highly conservative characteristics among members of the family Octodontidae were observed in the postcranial morphology of S. cyanus, although some characters are exclusive to this species.  The axial skeleton has seven cervical vertebrae, 12 or 13 thoracic, six or seven lumbar, four sacral, 16 to 18 caudal vertebrae, 12 or 13 ribs and a sternum with five sternebrae.  The elements of the scapular and pelvic girdles as well as forelimbs and hindlimbs are described in detail, except the carpus and tarsus due to their poor state of conservation, or because they not available.  The morphological pattern observed in the postcranial skeleton of S. cyanus conforms to a typical anatomical plan for terrestrial species, and some bones (mainly humerus and ulna) present characteristics associated with digging.  The information obtained provided will allow a better interpretation of the postcranial attributes, functionally related with different lifestyle, in a future, as well as the evolution of the traits in a phylogenetic context.

The Cotapata National Park and Natural Area for Integrated Management (PN-ANMI) is located on the eastern escarpments of the Eastern Cordillera in Bolivia.  It has an altitudinal range between 1,100-5,600 masl, with five altitudinally delimited ecological zones. There is great variability of environments, which generates great animal species diversity, varying according to elevation, and in association with changes in climatic and ecological conditions.  The aim of this study was to determine the pattern of richness and composition of small non-flying mammals along an altitudinal gradient in the PN-ANMI Cotapata and to evaluate responses of these species to the gradient.  We worked at three different elevations: Yungas Forest (1,400 masl), Cloud Forest (2,100 masl) and Yungas Paramo (3,500 masl).  Six temporary replicas were conducted.  For each sampling period we run three 250 m linear transects were placed, separated by 50 m attitudinally.  Each transect contained 25 sampling stations, with two snap traps.  With the exception of Yungas Paramo (due to the rocky ground), we also run transects of pitfall barrier traps (five buckets, every 5 m).  We captured 460 specimens corresponding to 20 species of rodents and two of marsupials.  Although, species richness (S) and diversity (Cinv) were higher in Cloud Forest (intermediate elevation; S = 11, Cinv = 4.30), followed by Yungas Forest (S = 9, Cinv = 3.47), and lower in Yungas Paramo (higher elevation; S = 8, Cinv = 2.12), only the diversity was significantly different (H = 7.0, n = 17, P = 0.03).  Species composition varied between places, showing the greatest turnover between Cloud Forest and Yungas Paramo, with a similarity of only 2 %.  Yungas Paramo had the highest number of exclusive species (seven of the eight registered).  The diversity was higher at medium altitude, giving a positive monoclinal hump-shaped pattern.  This variation, responds to climatic influences associated with changes in vegetation, where Cloud Forest provides a greater diversity of ecological niches.  The lower diversity in Yungas Paramo, and the almost total species turnover responds to inhospitable and stress conditions and to the physiological adaptations of these species to these elevations.

Woody plant encroachment (WPE) is reshaping the physiognomy of grasslands and savannahs worldwide.  At the same time, this habitat conversion is accelerating the loss of associated biodiversity.  In general, studies on WPE have focused on abiotic factors, singly or in combination, that trigger this phenomenon.  Despite its ecological relevance, very few studies have tackled the effects of WPE-spurred habitat transformation on animal species dependent on relatively open areas such as grasslands and savannas for survival. We studied a relict and almost extinct population of large, herbivorous guanacos (Lama guanicoe) in the Gran Chaco region, Santa Cruz department, Bolivia.  We tested whether guanacos were using habitats (at particular and distinct stages of WPE) in relation to their availability.  Although this species is considered a generalist herbivore.  We tested variation in habitat use focusing on two spatial scales.  First, at the landscape level, we performed aerial surveys.  Second, at the fine scale, we tracked six groups of guanacos for twenty months and documented the various habitats used within their approximate home ranges.  At both scales, we performed a Manly-Chesson’s index referring to the standardised proportional use of each habitat divided by the proportional availability of each, with the values for all habitats summing to 1.  An index value < 1 or > 1 suggests, respectively, that a habitat is avoided or selected.  We found a disproportionate use of open vegetation (scrubland and grassland) by guanacos in relation to habitat availability at both scales.  In addition, the current distribution range of the species is restricted to less than 800 km2 of the approximately 3,000 km² potentially available in 1998.  We confirmed a contraction between 1996 and 2006 in the distribution of the local Chacoan guanaco population from the area where guanacos were first monitored towards the Kaa-Iya National Park border.  Our results showed that guanacos are restricted to relatively open areas.  Furthermore, the observed reduction in the area previously occupied by the species could be the beginning of a distributional shift and potential loss of the guanaco’s geographic range due to habitat replacement.  The latter was also reflected in a previous dietary study of this population we found that guanacos largely consumed the native grass A. mendocina (Poaceae), which has shrunk in distribution by 90 % in this region over a 40 year period and is gradually being replaced by an invasive forb, Lippia sp.  Therefore, if the overall purpose on evaluating habitat use is to understand the basic requirements to sustain this population of guanacos, we need to highlight the poor quality and acute regression of the current preferred habitat.  In this case, habitat structure can have a profound effect on the success of the guanaco population recovery and its long-term establishment.  Therefore, we urge researchers and decision makers to look beyond the more direct human-induced pressures on the species, such as hunting, competition with domestic livestock and agricultural development and consider the importance of WPE as a direct driver for habitat loss. 

Jaguar populations have declined dramatically in the last century.  The Maya Biosphere Reserve (MBR) within the Selva Maya (SM) is a priority area for jaguar conservation.  Influential factors in the jaguar seasonal distribution include the availability of surface water in wetlands such as the “aguadas” and the availability of prey.  Aguadas are formed by isolated depressions in the landscape and serve as a water supply for wildlife during dry periods.  The goal of this study was to describe the visitation patterns of jaguars to aguadas in a Tropical forest at Dos Lagunas Protected Biotopo, a core zone of the MBR, Guatemala.  We used camera-trap data from seven aguadas during the dry seasons 2014-2017.  We determined visitation rates (VR, records for 1,000 trap-days) and activity patterns (AP) of jaguars for all years, aguadas, and sexes.  We tested for significant differences in AP between sexes, and we estimated the coefficient of overlap (D) for female and male jaguar activity.  We recorded 14 individuals (five females, eight males, and one unsexed) in 60 visit events.  Jaguars have significant more diurnal activity at aguadas, and showed a VR = 13.1 for 1,000 trap-days. VR varied between aguadas (VR = 9.5 – 19.4), years (VR = 1.9 – 39.2) and sexes (VR = 6.1 for females and 5.5 for males).  We did not find significant differences in the AP of female and male jaguars (P > 0.05). The coefficient of overlap between activity of females and males was D = 0.77 (95 % confidence interval: 0.70 to 0.84; P > 0.05).  Aguadas may represent regular sites of jaguar home-ranges overlap for the important resources they provide for wildlife during the dry season.  Aguadas could play an important role in the conservation and management of jaguar populations since the spatial distribution of these bodies of water is scattered, but ecologically important for jaguars within the MBR and the SM.  Aguadas also, are important landscape features that could influence the spatial interactions of individuals. We encourage jaguar researchers to increase investigation on jaguars visiting aguadas and other wetlands in the SM to better understand the jaguar activity patterns and sex-specific habitat requirements.

The ocelot is one of the six species of felids distributed in Mexico. This species is threatened with extinction and thus protected by the Mexican government. Knowledge about the environmental factors that affect its presence is a crucial step in identifying key areas and designing strategies for the conservation of this species. The aim of this study was to document the presence of the ocelot to determine its potential distribution and identify important conservation areas in the southern Sierra Madre Oriental and Sierra Negra of Puebla (as part of the northern Sierra Madre del Sur). We conducted camera-trap surveys from October 2013 through January 2014, placing 63 camera-trap stations distributed in both areas. The overall sampling effort was 2,381 trap-days. The presence of the ocelot was recorded in the Sierra del Abra-Tanchipa Biosphere Reserve, in San Luis Potosi and Sierra Negra in Puebla. An estimated 78 % of the study sites hold suitable environmental conditions for the potential presence of ocelots. The variables that jointly accounted for 65 % of the potential distribution were related to precipitation, namely precipitation of the driest trimester, of the wettest month, and of the warmest trimester. Our potential distribution models suggest the existence of priority regions for ocelot conservation. This research updates the present status of the ocelot in the Sierra Madre Oriental and Sierra Negra in Puebla, sites that have been subject to high habitat encroachment by human settlements.

The tapir (Tapirella bairdii) and the jaguar (Panthera onca) are two of the largest Neotropical mammal species suffering population declines caused by habitat loss and degradation and hunting. Tapirs and jaguars are considered endangered and near threatened, respectively, by the IUCN, and in Mexico, both species are listed as endangered and considered species with priority for conservation. These species are usually associated with large and remote areas of preserved forest. To evaluate local diversity of medium and large sized mammals, we placed five camera traps, three in old forest and two in secondary forest (445 trap days) at Ejido Ramos Millán (municipality of Minatitlán), on the northernmost part of the Uxpanapa Valley, in the Gulf of Mexico coastal plain, state of Veracruz, Mexico. This region has been highly transformed by human activities, where agricultural and livestock activities have caused the loss of most of its natural forests, resulting in a highly fragmented landscape, dominated by livestock fields, crops and secondary forests. Here we document images of three adult individuals of jaguar and two adult individuals of tapir, one of which was a lactating female, and one adult male tapir. The new records were 23 Km north of the most recent reports located in well preserved primary forests in the Uxpanapa/Chimalapas border area. Our results suggest that the highly fragmented tropical landscapes composed of both old-growth and secondary forests remnants, are able to provide sufficient resources to maintain at least temporarily individuals of jaguars and tapirs.

The genus Nephelomys comprises at least 13 taxa with altitudinal distribution ranging from 900 to 4,000 meters above sea level. Three species are currently known to occur in Venezuela, but some authors suggest that two additional taxa are present in Venezuelan Andes populations and consider N. meridensis as a species complex. We conducted geometric morphometric analyses of skulls and jaws from populations assignable to the monotypic species N. meridensis from the Venezuelan Andes, in order to examine and compare morphological variations in this species. We compared four localities (including the type locality of N. meridensis) situated in northern, central, and western portions of Cordillera de Mérida and the Tamá páramo. We created morphological landmarks on dorsal, ventral, lateral, and jaw views of each skull using the tpsDIG software. Significant differences were found in skull shape and isometric size in most of the populations examined. The discrimination and morphological differentiation of some of these groups with respect to the population from the type locality (Mérida) were aligned with the results from multivariate and cytogenetic analyses carried out previously by other authors. Our data support recognizing N. meridensis as a species complex, comprising at least three still undescribed taxa from the Yacambú National Park (cordillera de Mérida), La Trampita (cordillera de Mérida) and the Tamá páramo (Tamá massif). A more detailed taxonomic study of Nephelomys from Venezuela, molecular and linear morphometric analyses, and revision of morphological characters, are necessary to describe potential new taxa and determine the geographical distribution of the species in this genus.