Spiny Rat Research Articles

Cytogenetic data from remote areas of amazon: new karyotypes for spiny rats (Rodentia: Echimyidae)

Cytogenetic data from remote areas of amazon: new karyotypes for spiny rats (Rodentia: Echimyidae)

Does climate shape geographical morphological variation of spines in Neotropical spiny rats (Rodentia, Echimyidae, Trinomys)?

Abstract Flattened and flexible spiny hairs, the aristiforms, evolved independently in some lineages of rodents, but unlikely capable of causing severe damage to predators. Their biological roles are not yet clearly known and some different thermoregulatory functions have been proposed, often associated with severe climatic conditions but not yet tested. In this study we investigated whether climate may be a major factor shaping geographic variation of length and width of aristiform hairs of 2 species of Neotropical spiny rats of the genus Trinomys (Echimyidae) occurring in eastern Brazil: T. albispinus and T. setosus. Results revealed clinal variation in these hairs. While bioclimatic factors and geographic distance together accounted for up to a third of the morphometric variation, the exclusive impact of climate was limited, explaining only up to 3% of the observed variation. However, considering the close association between climate and geographic distance, the role of climate in shaping aristiform hair cannot be discounted. While our results did not fully support the hypothesis that well-developed, wide spiny hairs are selected for greater protection against rain for underhairs, they marginally supported their role in facilitating heat loss in warm environments by facilitating water condensation. More consistently, results show that narrow spiny hairs tended to evolve in cold environments, likely enhancing thermal insulation. The length of aristiform hair in T. albispinus also appeared to respond to this function, becoming longer in cold and high-altitude regions. However, we cannot rule out the possibility of an evolutionary response correlated with selection on underhairs. Future experimental studies should test the thermoregulatory function of flexible spiny hairs and investigate the geographic variation of these structures in other rodent species.

Zoonotic Ectoparasite Burden in House Rats (Rattus spp.) in Selected Urban and Rural Areas of NCR and CALABARZON

Rats and other mammalian species co-inhabiting or living in proximity with humans can serve as potential reservoir hosts and may contribute to the transmission of parasitic infections. Aside from endoparasites, ectoparasites such as lice, mites, ticks, and fleas, can also serve as vectors of various pathogens inducing diseases and contaminating the environment. This study aimed to determine the prevalence rate of Polyplax spinulosa (spiny rat louse) infestation among house rats in selected urban and rural areas in the Philippines. A total of 60 Rattus spp. were captured and examined. The overall prevalence rate of Polyplax spinulosa was 71.7% (43/60). Of the infestations, 23.3% (14/60) were recorded in Metro Manila while 48.3% (29/60) were recorded in CALABARZON. These results have revealed that rodents like rats play an important role in both direct and indirect transmission of zoonotic diseases since these pests themselves could be host to a variety of diseases. As a result, there is an immediate need to provide education and raise awareness about the role of rodents as reservoir hosts and vectors of these zoonotic diseases to develop long-term strategies for controlling and preventing rodent populations and the transmission of zoonotic ectoparasite infestation.

Where Are the Formerly Y-linked Genes in the Ryukyu Spiny Rat that has Lost its Y Chromosome?

It has been predicted that the highly degenerate mammalian Y chromosome will be lost eventually. Indeed, Y was lost in the Ryukyu spiny rat Tokudaia osimensis, but the fate of the formerly Y-linked genes is not completely known. We looked for all 12 ancestrally Y-linked genes in a draft T. osimensis genome sequence. Zfy1, Zfy2, Kdm5d, Eif2s3y, Usp9y, Uty, and Ddx3y are putatively functional and are now located on the X chromosome, whereas Rbmy, Uba1y, Ssty1, Ssty2, and Sry are missing or pseudogenized. Tissue expressions of the mouse orthologs of the retained genes are significantly broader/higher than those of the lost genes, suggesting that the destinies of the formerly Y-linked genes are related to their original expressions. Interestingly, patterns of gene retention/loss are significantly more similar than by chance across four rodent lineages where Y has been independently lost, indicating a level of certainty in the fate of Y-linked genes even when the chromosome is gone.

Immunogenetic-pathogen networks shrink in Tome’s spiny rat, a generalist rodent inhabiting disturbed landscapes

Anthropogenic disturbance may increase the emergence of zoonoses. Especially generalists that cope with disturbance and live in close contact with humans and livestock may become reservoirs of zoonotic pathogens. Yet, whether anthropogenic disturbance modifies host-pathogen co-evolutionary relationships in generalists is unknown. We assessed pathogen diversity, neutral genome-wide diversity (SNPs) and adaptive MHC class II diversity in a rodent generalist inhabiting three lowland rainforest landscapes with varying anthropogenic disturbance, and determined which MHC alleles co-occurred more frequently with 13 gastrointestinal nematodes, blood trypanosomes, and four viruses. Pathogen-specific selection pressures varied between landscapes. Genome-wide diversity declined with the degree of disturbance, while MHC diversity was only reduced in the most disturbed landscape. Furthermore, pristine forest landscapes had more functional important MHC–pathogen associations when compared to disturbed forests. We show co-evolutionary links between host and pathogens impoverished in human-disturbed landscapes. This underscores that parasite-mediated selection might change even in generalist species following human disturbance which in turn may facilitate host switching and the emergence of zoonoses.

Identification of a New Enhancer That Promotes Sox9 Expression by a Comparative Analysis of Mouse and Sry-Deficient Amami Spiny Rat

Introduction: Testis differentiation is initiated by the SRY gene on the Y chromosome in mammalian species. However, the Amami spiny rat, Tokudaia osimensis, lacks both the Y chromosome and the Sry gene and acquired a unique Sox9 regulatory mechanism via a male-specific duplication upstream of Sox9, without Sry. In general mammalian species, the SRY protein binds to a testis-specific enhancer to promote SOX9 gene expression. Several enhancers located upstream of Sox9/SOX9 have been reported in mice and humans. In particular, the binding of SRY to the highly conserved enhancer Enh13 is thought to be a common mechanism underlying testis differentiation and sex determination in mammals. Methods: Sequences of T. osimensis homologues of three Sox9 enhancers that were previously reported in mice, Enh8, Enh14, and Enh13, were determined. We performed in vitro assays to confirm enhancer activity involved in Sox9 regulation in T. osimensis. Results: T. osimensis Enh13 showed enhancer activity when co-transfected with NR5A1 and SOX9. Mouse Enh13 was activated by NR5A1 and SRY; however, T. osimensis Enh13 did not respond to SRY, even though the binding sites of SRY and NR5A1 were conserved. To identify the key sequence that is present in mouse but absent from T. osimensis, we performed reporter gene assays using vectors in which partial sequences of T. osimensis Enh13 were replaced with mouse sequences. For T. osimensis Enh13 in which the second half (approximately 430 bp) was replaced with the corresponding mouse sequence, activity in response to NR5A1 and SRY was recovered. Further, reporter assays revealed that multiple regions in the second half of the mouse Enh13 sequence are required for the response to NR5A1 and SRY. The latter 49 bp was particularly important and contained four binding sites for three transcription factors, POU2F1, HOXA3, and GATA1. Conclusion: We showed that there are unknown sequences responsible for the interaction between NR5A1 and SRY and mEnh13 based on comparative analyses of Sry-dependent and Sry-independent species. Our comparative analyses revealed new molecular mechanisms underlying mammalian sex determination.

Pathological features of intrathoracic histiocytic sarcoma in an Amami spiny rat (Tokudaia osimensis).

A 4-year 9-month-old Amami spiny rat reared in a zoo died following a history of anorexia, weight loss, and respiratory distress. At necropsy, neoplastic tissues were found along the pleura and adhered to the thoracic wall, heart, and lungs. Histologically, the tumor was composed of diffuse, patternless sheets of large round to polygonal neoplastic cells with abundant eosinophilic cytoplasm, and multinucleated giant cells were often present. Metastatic lesions were observed in the abdominal lymph nodes. Neoplastic cells were immunopositive for vimentin, Iba-1, and CD204, and negative for E-cadherin and S100. Based on these findings, the tumor was diagnosed as histiocytic sarcoma. Compression of the lungs by the tumor may have caused respiratory failure and led to death.

Phylogenomics and species delimitation of an abundant and little-studied Amazonian forest spiny rat

Species delimitation studies based on integrating different datasets such as genomic, morphometric, and cytogenetics data are rare in studies focused on Neotropical rodents. As a consequence, the evolutionary history of most of these genera remains poorly understood. Proechimys is a highly diverse and widely distributed genus of Neotropical spiny rats with unique traits like multiple sympatry, micro-habitat segregation, and fuzzy species limits. Here, we applied RAD-Seq to infer the phylogenetic relationships, estimate the species boundaries, and estimate the divergence times for Proechimys, one of the most common and least studied small mammals in the Amazon. We tested whether inferred lineages in the phylogenetic trees could be considered distinct species based on the genomic dataset and morphometric data. Analyses revealed the genus is not monophyletic, with Proechimys hoplomyoides sister to a group of Hoplomys gymnurus + all other Proechimys species, contesting the generic status of Hoplomys. There are five main clades in Proechimys stricto sensu (excluding H. gymnurus and P. hoplomyoides). Species delimitation analyses supported 25 species within the genus Proechimys. The five main clades in Proechimys stricto sensu also showed similar ages for their origins, and two rapid diversification events were identified in the Early Pliocene and in the Early Pleistocene. Most cases of sympatry in Proechimys occur among species from the different main clades, and although Proechimys is an inhabitant of the Amazon, three species occupied the Cerrado biome during the Pleistocene. We could associate available nominal taxon, cytogenetics information, and DNA sequences in Genbank to most of the 25 species we hypothesized from our delimitation analyses. Based on our analyses, we estimate that eight forms represent putative new species that need a taxonomic revision.

The distribution of bushmeat mammals in unflooded forests of the Central Amazon is influenced by poaching proxies.

Medium to large rainforest mammals are key conservation flagship groups that offer non-redundant ecosystem functions, but anthropic pressures, such as illegal hunting, may strongly affect their occupancy in Amazonia. We combined camera traps and occupancy models to assess the influence of distance from human settlements, the number of families per settlement and the synergetic effect of the average weight of 27 species on the occupancy probability of mammals. Specifically, we classified mammal species according to the game preferences of hunters (i.e. a group of species depleted for bushmeat, a group of species hunted for retaliation and a group of non-hunted species). We also accounted for the influence on the detection probability of each group of both the number of days each camera operated and the body weight of mammals. The occupancy probability of the bushmeat group (i.e. deer, peccaries, agoutis, pacas and armadillos) was lower at locations closer to human settlements. Still, the number of families correlated positively with occupancy, with the occupancy probability of the group being slightly higher at sites with more families. This difference was probably due to larger and more abundant crops and fruiting trees attracting wildlife at such sites. Conversely, the occupancy probability of the retaliation group (i.e. carnivores) and the non-hunted group (i.e. opossums, spiny rats, squirrels and anteaters) were indifferent to anthropogenic stressors. The detection probability of the non-hunted and particularly the most depleted species correlated negatively with body weight. This may suggest that larger species, especially those from the bushmeat group, are rarer or less abundant in the system, possibly because they are the preferable target of hunters. In the long term, locals will likely need to travel long distances to find harvest meat. Poaching also threatens food security since game bushmeat is an essential source of protein for isolated rural Amazonians.

Spatial and social organization of the burrowing rodent Clyomys laticeps (Thomas, 1909)

Abstract Burrowing rodents display diverse patterns of social organization, ranging from solitary to group living. Differences in social organization are often inferred from patterns of space use, particularly differences in the degree to which individual home ranges overlap. Here, we characterize patterns of space use in a poorly studied species of burrow-dwelling echimyid rodent, the Broad-headed Spiny Rat (Clyomys laticeps). Specifically, we use radiotelemetry studies of a free-living population in Parque Estadual da Serra de Caldas Novas (Goiás, Brazil) to evaluate previous, apparently contradictory reports suggesting that this species is both solitary and social. A total of 20 adult (12 females, 8 males) C. laticeps were monitored via telemetry during two consecutive cycles of annual wet and dry seasons. The resulting data indicate that although overlap of individual home ranges was common, co-occurrence of adults in time and space was rare and was limited to male–female pairs, a pattern that is most consistent with a solitary lifestyle in which individuals occupy distinct burrow systems. Neither sex nor season affected spatial overlap; this outcome is consistent with evidence suggesting that reproduction in this species occurs throughout the year. Although home ranges for males were larger than those for females, areas occupied by both males and females overlapped with multiple opposite-sex individuals, making it difficult to determine from spatial data whether the study population was polygynous or polygynandrous. While genetic data are needed to characterize fully the mating system of these animals, our analyses provide the first detailed information regarding spatial relationships in C. laticeps, thereby allowing more accurate placement of this species within a larger, comparative behavioral framework and facilitating efforts to identify factors contributing to social diversity among burrow-dwelling rodents.

Influence of tree-fall gaps on directional seed dispersal by small mammals in Central Panama

Small mammals, particularly rodents, are often important seed-dispersal agents in Neotropical forests. Directional seed dispersal into tree-fall gaps may enhance seedling survival of light-demanding species and thus influence forest regeneration. To examine this proposition, we tracked seeds of a light-demanding palm (Attalea butyracea), with a focus on spiny rats (Proechimys semispinosus), the most-likely seed-removal agents. We established seed-removal stations at three distances relative to 28 gaps (gap center, gap edge, and intact forest 10 m from a gap edge) in a lowland forest in Central Panama. We placed five fresh fruits (with their seed) in semi-permeable exclosures to exclude larger mammals at each station and tracked the directions in which seeds were moved and deposited intact. More seeds were moved toward or into gaps when removed from gap center or edge stations; however, seeds dispersed from intact forest stations showed no such directionality. Small mammals may have dispersed seeds into and within tree-fall gaps because they favored caching seeds in areas that offered increased cover, which is typical of gaps, and consequently protection from predation. The lack of directional dispersal from intact forest stations may have been because spiny rats were able to find sufficient cover in the young intact forest that was closer than the gaps. In older forest, the contrast between intact forest and gaps may be greater, resulting in directed dispersal into gaps.

Concerns over the declining human Y-chromosome and social functioning

In humans, like other mammals, females have two X chromosomes and males have one X and one Y chromosome. The Y chromosome contains a sex-determining gene SRY that kick-starts male development in the embryo and activates other genes that regulate the testicular development. Researchers have found that the Y chromosome seems to be disappearing, as seen in many other mammals, including rodents. The male eastern Europe vole and the spiny rats of Japan have completely lost their Y chromosomes and the Sry gene. However, the SOX9 protein plays a key role there in determining their sex. The new finding so support the possibility that humans too, may evolve a new sex determining mechanism. The sex chromosome genes act within cells to cause differences in phenotypes of XX and XY cells throughout the body. In the gonad, they determine the type of gonad, leading to differences in secretion of testicular vs. ovarian hormones, which cause further sex differences in tissue function. The human brains, as shown by neuroimaging, demonstrate variation in different areas of the brain that are associated with both differences in gonadal hormones, and in the number of X and Y chromosomes. In humans, males and females are different because of innate biological differences, and also they have different social and physical environments. Biologists tend to emphasize the importance of biological variables, and sociologists tend to emphasize the role of gendered environments. The Sry and the other Y-linked genes not only determine the differences in gonad development, they are also linked to maintaining gender balance (biologically) and various functions in the brain, including appropriate social responses by supporting behavioral flexibility, attention and emotion. In this article, we have reviewed the function of the Y chromosome and the Sry gene and their possible alternatives in case of their future extinction.

Diversification of Amazonian spiny tree rats in genus Makalata (Rodentia, Echimyidae): Cryptic diversity, geographic structure and drivers of speciation.

Amazonian mammal diversity is exceptionally high, yet new taxonomic discoveries continue to be made and many questions remain for understanding its diversification through time and space. Here we investigate the diversification of spiny rats in the genus Makalata, whose species are strongly associated with seasonally flooded forests, watercourses and flooded islands. We use a biogeographical approach based on a mitochondrial cytochrome b gene through divergence time estimation and reconstruction of ancestral areas and events. Our findings indicate an ancient origin of Makalata for the Guiana Shield and Eastern Amazonia as ancestral area. A first cladogenetic event led to a phylogeographic break into two broader clades of Makalata through dispersal, implying a pattern of western/Eastern Amazonian clades coinciding with the Purus Arch (middle Miocene). Most of subclades we infer originated between the late Pliocene to the early Pleistocene, with few recent exceptions in the early Pliocene through dispersal and vicariant events. The hypothesis of rivers as dispersal barriers is not corroborated for Makalata, as expected for mammalian species associated with seasonally flooded environments. We identify two key events for the expansion and diversification of Makalata species: the presence of geologically stable areas in the Guiana and Brazilian shields and the transition from lacustrine conditions in western Amazonia (Acre system) to a river system, with the establishment of the Amazon River transcontinental system and its tributaries. Our results are congruent with older geological scenarios for the Amazon basin formation (Miocene), but we do not discard the influence of recent dynamics on some speciation events and, mainly, on phylogeographic structuring processes.

Species diversity, abundance, and movement of small mammals in the dry evergreen forest at Khao Yai National Park, Thailand

Abstract. Chanachai Y, Nathalang A, Duengkae P, Sukmasuang R. 2022. Species diversity, abundance, and movement of small mammals in the dry evergreen forest at Khao Yai National Park, Thailand. Biodiversitas 23: 5892-5901. Small mammals play an integral role in the forest ecosystem. This research was conducted on The Mo Singto Forest Dynamics Plot, Khao Yai National Park. Trapping of small mammals was carried out in June-September 2019 and from January-April 2020 based on a total of 64 Tomahawk for small mammal live traps were systematically placed in an 8×8 grid of 20 m intervals, ripe bananas and palm oil as bait was used. Trap cages were opened for 3 consecutive months per season in each study period covering a total study period of 1 year. The result showed that a total of 4015 individuals from 9 species, 9 genera, 4 families and 3 orders were captured with a sampling effort of 32,555 trap nights. The most common species were Red Spiny Rat (Maxomys surifer), followed by Northern Tree Shrew (Tupaia belangeri), Long-tailed Giant Rat (Leopoldamys sabanus), Indochinese Ground Squirrel (Menetes berdmorei), Asian House Rat (Rattus tanezumi), Indomalayan Niviventer (Niviventer fulvescens), Savile's Bandicoot Rat (Bandicota savilei), (Tamiops mcclellandii), and Short-tailed Gymnure (Hylomys suillus) respectively. Considering the number of small mammals caught, Maxomys surifer was the most abundant, accounting for 61.69% of all mammals caught. The sex ratio was found to somewhat favor females in both seasons. This study indicated that the small mammal diversity was high in the primary dry evergreen forest. These results have important implications not only for conservation but are also useful for further investigation if there is any disturbance or change in the area or any potential disasters that may occur in the future.

Occurrence of the mite Acanthonyssus proechimys (Mesostigmata: Macronyssidae) on a spiny rat in Brazil

ABSTRACT Macronyssid mites are ectoparasites of terrestrial vertebrates. We slide-mounted and re-examined mite material collected in a 1987-1989 expedition to Maracá Ecological Station, Roraima State, Brazil. The specimens were identified as Acanthonyssus proechimys Yunker and Saunders (Mesostigmata: Macronyssidae), which were collected parasitizing a South American spiny rat, Proechimys sp. This represents the first record of Acanthonyssus in Brazil.

DIVERSITY OF NON-VOLANT SMALL MAMMALS IN PULAU TINGGI, JOHOR, MALAYSIA

A non-volant small mammal survey was conducted at Pulau Tinggi between July and September 2019. This study aimed to provide baseline data for non-volant small mammals in Pulau Tinggi by setting 55 cage traps and 20 pitfalls for 44 trapping nights. A total of 20 individuals of non-volant small mammals were documented, representing five species from three families: Soricidae, Sciuridae and Muridae. The Rajah spiny rat (Maxomys rajah) and the Red spiny rat (Maxomys surifer) were the most abundant species (n=6) of non-volant small mammals in Pulau Tinggi. The Malayan field rat (Rattus tiomanicus) was the least species (n=1). The Malayan shrew (Crocidura malayana) is the only shrew recorded on the island. The analysis of similarities between our study site and other Malaysian islands reveals that Pulau Tinggi shares more similarities with Pulau Pangkor and Pulau Perhentian than Pulau Tioman. The small mammal richness on Pulau Tinggi is relatively low compared to other islands, most likely due to the study site’s limited coverage and time constraints. Long-term monitoring is required to determine the true diversity of species and distribution of small mammals on Pulau Tinggi.

Turnover of mammal sex chromosomes in the Sry-deficient Amami spiny rat is due to male-specific upregulation of Sox9

Mammalian sex chromosomes are highly conserved, and sex is determined by SRY on the Y chromosome. Two exceptional rodent groups in which some species lack a Y chromosome and Sry offer insights into how novel sex genes can arise and replace Sry, leading to sex chromosome turnover. However, intensive study over three decades has failed to reveal the identity of novel sex genes in either of these lineages. We here report our discovery of a male-specific duplication of an enhancer of Sox9 in the Amami spiny rat Tokudaia osimensis, in which males and females have only a single X chromosome (XO/XO) and the Y chromosome and Sry are completely lost. We performed a comprehensive survey to detect sex-specific genomic regions in the spiny rat. Sex-related genomic differences were limited to a male-specific duplication of a 17-kb unit located 430 kb upstream of Sox9 on an autosome. Hi-C analysis using male spiny rat cells showed the duplicated region has potential chromatin interaction with Sox9. The duplicated unit harbored a 1,262-bp element homologous to mouse enhancer 14 (Enh14), a candidate Sox9 enhancer that is functionally redundant in mice. Transgenic reporter mice showed that the spiny rat Enh14 can function as an embryonic testis enhancer in mice. Embryonic gonads of XX mice in which Enh14 was replaced by the duplicated spiny rat Enh14 showed increased Sox9 expression and decreased Foxl2 expression. We propose that male-specific duplication of this Sox9 enhancer substituted for Sry function, defining a novel Y chromosome in the spiny rat.

Effects of water restriction and dirt on grooming behavior in neotropical rodents (Trinomys setosus and T. yonenagae) (Echimyidae)

Grooming in rodents presents an evolutionarily conserved behavioral pattern that may cause water loss since saliva is deposited during washing onto large body surfaces. Trinomys yonenagae and Trinomys setosus are sister species of spiny rats occurring in Brazil, the former inhabiting a paleodesert of fixed dunes in the Caatinga, the latter being found in mesic environments of the Atlantic Forest. Consequently, it is expected that both species evolved under different selective pressures related to water balance, with T. yonenagae presenting mechanisms for dealing with water deprivation not found in T. setosus. Reduction of self-cleaning expression seems to offer a possible way to save water, as previously suggested by studies of the sand-dwelling spiny rat. Therefore, we propose to investigate grooming under four conditions: 'control' (C), a regimen of 'water restriction' (WR), of 'dirt' (D), and the combination of both conflicting stimuli (WR + D), in T. setosus, T. yonenagae, and Rattus norvegicus to compare the behavioral responses of these species. The main differences are observed in the forest dweller: T. setosus expresses a low relative duration of face washing under C, whose value is intermediate between the ones found in the two other species. WR treatment does not alter this pattern, however, the addition of dirt (D, WR + D) significantly increases the relative duration of washing in relation to C. Locomotor activity is decreased both in T. setosus and Wistar rats when they are under WR, a situation that could jeopardize antipredatory performance. T. yonenagae, the sand dweller, maintains a significantly lower expression of washing under C, as previously suggested, and under WR, D and WR + D. In addition, differently from the other two species the sand dweller maintains a normal activity level during all treatments. This study suggests differences in grooming as a strategy alluding to water balance by the two spiny rats inhabiting different ecosystems. A significantly clear pattern that saves water is observed in T. yonenagae, which probably has contributed to his evolution in one of the hottest semiarid areas of the world.

Hidden diversity of the genus Trinomys (Rodentia: Echimyidae): phylogenetic and populational structure analyses uncover putative new lineages

Abstract Trinomys, one of the most species-rich spiny rat genera in Brazil, is widely distributed in Caatinga, Cerrado and Atlantic Forest biomes, and currently includes ten recognized species, three of which are polytypic. Although some studies employing molecular data have been conducted to better characterize phylogenetic relationships among species, 19 nominal taxa have been suggested, implying considerable incongruence regarding species boundaries. We addressed this incongruence by intensively sampling all species across the geographic distribution of the genus. In addition to publicly available data, we generated 182 mt-Cytb gene sequences, and employed phylogenetic and computational species delimitation methods to obtain a clearer picture of the genus diversity. Moreover, we evaluated populational diversity within each accepted species, considering their geographical distribution and a timescale for the evolution of the genus. Beyond confirming the general patterns described for the evolution of the group, this new analysis suggests that Trinomys is comprised of at least 16 evolutionary lineages, 13 of them recognized as species or subspecies, and three never before characterized. This study highlights the importance of increased sample sizes and computational species delimitation methods in uncovering hidden diversity in Trinomys.

Pelvic sexual dimorphism and its association with cranial morphology in Neotropical spiny rats (Rodentia, Echimyidae)

Pelvic sexual dimorphism and its association with cranial morphology in Neotropical spiny rats (Rodentia, Echimyidae)