Echimyid Rodents Research Articles

Litter size and embryo implantation in Neotropical rodents

Diogo Loretto Oecologia Australis 0 0 2014-02-04T21:20:00Z 2014-02-04T21:20:00Z 1 224 1281 UFES 10 3 1502 14.0 Normal 0 false false false PT-BR JA X-NONE Research on the biology of Neotropical small mammals has increased in recent decades, and many studies have emphasized ecological and population attributes, but information on reproduction is still scarce. Reproduction is one of the most important natural history attributes because it is tied to almost every structural, physiological and behavioural adaptation of an individual or a species. Most research on rodent reproduction concentrates in temperate areas and there is an evident lack of data from the Neotropical region. We compared reproductive patterns of sigmodontine and echimyid rainforest rodents. We obtained necropsy data from 135 specimens collected in the field and belonging to 22 species of sigmodontine and 8 species of echimyid rodents. We estimated embryonic litter size by counting the number of embryos or the number and placement of placental scars in pregnant and parous females. Although smaller in body size, sigmodontines have larger litter sizes (3.6 ± 1.2) than echimyids (2.1 ± 0.7), indicating a tendency toward r and k reproductive strategies, respectively. Embryonic litter size in pregnant females was not statistically different from the number of placental scars, so the latter is a reliable estimate of the former in both sigmodontines and echimyids. Embryo implantation is asymmetric regarding uterine horns in sigmodontines, with predominance in the right horn, but not in echimyids. The relevance and biological implications of such patterns are still unknown.

Aggressive and investigative behaviors of two sympatric species of echimyid rodents, Proechimys semispinosus and Hoplomys gymnurus, in Central Panama

An understanding of the mechanisms that allow ecologically similar species to coexist is critical in making effective conservation and restoration decisions. This understanding is especially important when considering species that play critical roles in forest regeneration. Small mammals influence Neotropical forest regeneration following disturbance through their actions as seed dispersers and seed predators. In Panama, the Central American spiny rat (Proechimys semispinosus) and the armored rat (Hoplomys gymnurus) persist sympatrically despite a similar diet and seasonal food resource limitation. To study the relationship between these species, we conducted behavioral arena trials to analyze interspecific and intraspecific interactions. Our goal was to determine whether behavioral dominance between H. gymnurus and P. semispinosus exists, potentially reducing the intensity of aggressive competition and allowing the two species to coexist sympatrically. Aggression data were analyzed using a zero-inflated negative binomial regression model showing that species pairing was a significant predictor of aggression, supporting the existence of behavioral dominance by P. semispinosus over H. gymnurus. Investigative behavior data were analyzed using the Kruskal–Wallis test and showed a significantly higher level of investigative behavior for P. semispinosus towards H. gymnurus during the dry season when resources are scarce compared to the wet season when resources are plentiful.

Spacing patterns and social mating systems of echimyid rodents

Echimyid rodents are widely distributed and abundant throughout most of the Neotropics. I review the available information on spacing patterns and mating systems and develop a general framework for understanding variation among populations and species. In most studied species males have larger home ranges than do females, and overlap with either sex can range from 0% to nearly 100%. Males typically display more overlap with both other males and females than do females. Although lack of overlap has been interpreted as territoriality, most such cases have been from populations at low densities. Individuals of those same species show considerable overlap at higher densities. I suggest that individuals typically are not territorial but instead merely space themselves out when vacant space is abundant. Individuals are then facultatively monogamous because multiple mates are not available. As densities increase male home ranges overlap more simply because their home ranges are larger than those of females. Males then can acquire multiple mates, and polygyny becomes evident. At the highest densities multiple mates are available for both males and females, and promiscuity results. The mating system within a given population of many echimyids therefore depends upon density, which in turn is determined primarily by resource availability.

Pequenos mamíferos não voadores em fragmentos de Mata Atlântica e áreas agrícolas em Viana, Espírito Santo, Brasil

Nós inventariamos os pequenos mamíferos não-voadores em Viana, Espírito Santo, sudeste do Brasil, em 1981-1982 e 2006-2007. Foram capturados 439 pequenos mamíferos não-voadores pertencentes a três ordens (Didelphimorphia, Rodentia e Lagomorpha) e seis famílias (Didelphidae, Sciuridade, Cricetidae, Muridae, Echimyidae e Leporidae). As espécies mais abundantes foram os roedores Akodon cursor e Nectomys squamipes e o marsupial Metachirus nudicaudatus. Registramos pela primeira vez a ocorrência do roedor equimídeo Euryzygomatomys spinosus no estado do Espírito Santo. A riqueza específica (S = 21) e o índice de diversidade de Shannon (H = 2,23) estão entre os maiores registrados para pequenos mamíferos da Mata Atlântica no estado, mesmo quando comparados aos valores obtidos para unidades de conservação. Esses maiores valores de riqueza e diversidade encontrados estão provavelmente associados à heterogeneidade de hábitat e evidenciam a necessidade de conservação dos fragmentos florestais de Viana, os quais são importantes depositários da biodiversidade da Mata Atlântica.

Affiliation in Four Echimyid Rodent Species based on Intrasexual Dyadic Encounters: Evolutionary Implications

AbstractIn this work we explored the evolution of sociality in cursorial echimyids by comparing affiliation among three species of Trinomys and one species of Thrichomys. We captured specimens of Trinomys yonenagae, Trinomys albispinus minor, and Thrichomys apereoides in areas of the Brazilian semiarid Caatinga, and Trinomys iheringi denigratus in one area of Atlantic Forest. For each species, we recorded 12 intra‐sexual dyadic encounters in a neutral arena (six between males and six between females) in order to test the hypothesis that species and sex influence level of affiliation. This response variable was assessed based on an affiliation index, calculated as the proportion of the total number of affiliative behaviors to the total number of social behaviors exhibited by the dyad during each encounter. Hypothesis test was performed by means of a parametric two‐way anova. The test was able to detect significant differences only among species, not among sexes. Trinomys yonenagae was the most affiliative species, while T. apereoides and T. albispinus minor were the most agonistic ones. Trinomys iheringi denigratus showed an intermediate pattern. We suggest, based on out‐group comparison, that affiliation in Trinomys increased in the lineage containing T. iheringi denigratus and T. yonenagae and that higher affiliation in the last species can be adaptive to the life in the desert‐like habitat where it lives.

Late Holocene extinction of Puerto Rican native land mammals

West Indian land mammals have suffered the most severe extinctions of any Holocene mammal faunas. However, 'last-occurrence' dates based on radiometric or robust stratigraphic data remain unavailable for most West Indian species, making it impossible to identify factors responsible for these extinctions. Here, we present new radiometric dates from archaeological and palaeontological sites on Puerto Rico, the only Greater Antillean island to have lost all native land mammals. Although it has been suggested that these species died out earlier than other West Indian mammals, we demonstrate that Puerto Rican mammal last-occurrence dates are in close agreement with those from other Antillean islands, as several species in fact persisted for millennia following Amerindian arrival. Echimyid rodents and nesophontid 'island-shrews' were still present on Puerto Rico approximately 1000 years BP, and probably became extinct following European arrival. The large (13kg) heptaxodontid rodent Elasmodontomys obliquus also appears to have survived for over 2000 years after Amerindian colonization, suggesting that at least some large West Indian mammals became extinct in protracted pre-European 'sitzkrieg'-style events rather than 'blitzkrieg'-style overkill.

LAELAPINE MITES (ACARI: LAELAPIDAE) ASSOCIATED WITH SMALL MAMMALS FROM AMAZONAS, BRAZIL, INCLUDING A NEW SPECIES FROM MARSUPIALS

An intensive survey of ectoparasitic arthropods associated with small mammals in upland forests near Manaus, Brazil, provides information on the taxonomy and host distribution of laelapine mites in the Amazonian Region. We identified 5 genera and 21 species of these mites by comparison with representative museum specimens, the taxonomic literature, and, when possible, the original type specimens. These mites are host specific, with associations ranging from strict monoxeny (18 species) to oligoxeny (1 species) and pleioxeny (2 species). Marsupials were infested with species of Androlaelaps, echimyid rodents with Tur, and sigmodontine rodents with Gigantolaelaps, Laelaps, and Mysolaelaps. Androlaelaps bergalloi, a new species of Laelapinae, is described from the pelage of the marsupial Monodelphis brevicaudata.

Relationships among extant and fossil echimyids (Rodentia: Hystricognathi)

The echimyid rodents are the most diverse group of Neotropical hystricognaths, with approximately 40 extant and fossil genera. Craniodental characters are proposed in order to formulate hypotheses of phylogenetic relationships within the Echimyidae. A data matrix of 54 taxa and 50 characters is constructed and submitted to parsimony analyses using PAUP and WinClada programs. Analysis of the complete data set results in 47 448 most parsimonious trees 107 steps long. These trees are summarized in a strict consensus tree, which is taken as the main phylogenetic hypothesis resulting from this study. The monophyly of several currently recognized supraspecific taxa is not corroborated. These are: the subfamilies Eumysopinae, Echimyinae, Myocastorinae and Adelphomyinae; and the genera Proechimys, Echimys and Makalata. Conversely, the monophyly of Dactylomyinae and Trinomys is supported. New associations are proposed: (1) a clade comprising the extant Carterodon, Clyomys and Euryzygomatomys and the fossil Pampamys and Theridomysops placed at the base of the crown-group Echimyidae; (2) a clade uniting Proechimys, Hoplomys and Trinomys, which is the sister-taxon of (3) a clade including Mesomys, Lonchothrix, Myocastor and a clade with extant dactylomyines and echimyines and associated fossil taxa. Based on this phylogenetic hypothesis, patterns of tooth evolution in Echimyidae are discussed, and minimum ages for the divergence events within the family are estimated.

Ultrastructure of echimyid and murid rodent spines

AbstractAristiform spines of the rodents Niviventer fulvescens, Maxomys surifer, Hoplomys gymnurus and 17 species of Proechimys (representing both recognized subgenera and all nine species groups) were studied qualitatively using scanning electron microscopy (SEM) and quantitatively by measuring seven linear dimensions. SEM was used to examine spine tips, bases, longitudinal furrows and cross sections. Spines of the murid rodents N. fulvescens and M. surifer differed from those of the echimyid rodents H. gymnurus and Proechimys spp. in possessing a smaller base with a longer, narrower neck, scaled rather than ridged longitudinal furrows, and a solid internal core and large lacunae at the spine margins. Spines of H. gymnurus differed from those of Proechimys spp. in being considerably more robust with a stout neck at the base, an abruptly‐tapering tip and a dense inner layer with a series of smaller lacunae at the spine margins. A factor analysis of spine measurements revealed major differences among N. fulvescens, M. surifer, H. gymnurus, the Proechimys subgenus Trinomys and the nine Proechimys species groups within the subgenus Proechimys. However, all Proechimys species groups clustered closely together. A discriminant function analysis of the nine Proechimys species groups provided generally limited discriminatory power. Although spines are distinct at the generic and subgeneric levels, spines may possess limited diagnostic structure at the level of species within the subgenus Proechimys.

Karyological and morphometric variation in the genus Thrichomys (Rodentia: Echimyidae)

Summary We describe two new karyotypes for the echimyid rodent genus Thrichomys , based on samples from the type locality of Thrichomys apereoides (Lund, 1839), Lagoa Santa, Minas Gerais, eastern Brazil, and from the north Pantanal region, near Cuiaba, state of Mato Grosso, western Brazil. These karyotypes are described using GTG- and CBG-banding and silver staining techniques, and compared with karyotypes from northeastern Brazil previously described for the genus. The karyotype of Thrichomys apereoides from Lagoa Santa shows 2n = 28 and FN 50, with constitutive heterochromatin showing pericentromeric bands in all autosomes except in two pairs, and nucleolar organizing regions (Ag-NOR sites) coincident with the secondary constriction on the short arm of pair two. The karyotype of the specimens from the north Pantanal region shows 2n = 34 and FN = 64, with C-bands restricted to the sexual chromosomes, whereas Ag-NOR sites are coincident with the secondary constrictions. A multivariate analysis of craniometric traits including the type series of Thrichomys apereoides (Lund) from Lagoa Santa, deposited in the Copenhagen Museum, the sample from the north Pantanal region (Mato Grosso) and a sample from Jaiba in the north of the state of Minas Gerais was also performed. The results show that the samples from the north Pantanal region and Lagoa Santa are completely separated from each other with respect to a main axis of variation summarizing cranial shape. These results, gauged by the analysis of the karyological variation among samples from different localities support the revalidation of Thrichomys pachyurus (Wagner, 1845).

A new species of laelapine mite (Acari: Parasitiformes: Laelapidae) associated with Proechimys dimidiatus in the Atlantic forests of Brazil.

Tur megistoproctus, a new species of Laelapinae, is described from the pelage of the echimyid rodent Proechimys dimidiatus from the Atlantic forests of Ilha Grande, south of Rio de Janeiro. Measurements and illustrations are included for females and males. Another laelapine mite species, Tur turki Fonseca, co-occurred with T. megistoproctus in our studies and was recorded from the same host individuals and localities. These 2 laelapine mite species appear to be exclusively associated with a complex of echimyid rodent species (subgenus Trinomys) in the Atlantic forests of southeastern Brazil.

Activity Pattern of Echimyid Rodent Species from the Brazilian Caatinga in Captivity

The activity patterns of two closely related echimyid rodents (spiny rats) of the Brazilian Caatinga were studied. One species, Proechimys [Trinomys] yonenagae, is a fossorial dweller of fixed sand dunes. P. [T.] albispinus, inhabits remnants of the Atlantic rainforest areas. A third species, Trichomys apereoides, collected in granite formations in the Caatinga was also studied. The animals were kept individually in cages under controlled conditions and light-dark cycle of 12:12 h. Data were collect by Scan sampling every 2 h, over 3 days, and were analyzed by Cosinor method. All species were nocturnal. P. yonenagae showed a regular pattern of circadian activity and restricted its activity to subjective night. P. albispinus showed an intermittent pattern of activity, especially in the dark phase. T. apereoides showed a bimodal pattern with high crepuscular peaks of activity. A high level of synchrony was found in the activity among individual P. yonenagae. No sex differences were found in behavioral patterns of either P. yonenagae or P. albispinus. Since the two species of Proechimys share a common ancestor, the differences that were found stress the importance of external selection over circadian rhythmicity.

Evolution of South American spiny rats (Rodentia, Echimyidae): the star-phylogeny hypothesis revisited

We analyzed the phylogenetic relationships of echimyid genera based on sequences of the cytochrome b, 12S, and 16S mitochondrial genes. Our results corroborate the monophyly of Octodontoidea and the rapid diversification of echimyid rodents as previously proposed. The analyses indicate that the family Echimyidae, including Myocastor to the exclusion of Capromys, is paraphyletic, since Capromys and Myocastor are well-supported sister-taxa. We therefore suggest the inclusion of both Capromys and Myocastor in the family Echimyidae. Five other suprageneric clades are well supported: Dactylomys + Kannabateomys, Euryzygomatomys + Clyomys, Proechimys + Hoplomys, Mesomys + Lonchothrix, and Makalata + ( Echimys + Phyllomys). Trinomys and Thrichomys have no clear close relatives, and Isothrix emerged as sister to Mesomys + Lonchothrix, but with no support. We suggest that most of the cladogenesis leading to the extant echimyid genera probably occurred during the Late Miocene, about eight million years ago.

GEOGRAPHIC VARIATION IN CRANIAL MORPHOLOGY IN THRICHOMYS APEREOIDES (RODENTIA: ECHIMYIDAE). I. GEOMETRIC DESCRIPTORS AND PATTERNS OF VARIATION IN SHAPE

Geometric descriptors were used to describe variation in cranial shape within and among populations of the echimyid rodent Thrichomys apereoides from localities in northeastern, central, and southeastern Brazil. Variation in shape based on dorsal, ventral, and lateral views of the skull, as inferred from contribution of uniform components and partial warps, was attributable to localized rather than global changes in morphology of the skull. Each view of the skull showed characteristic variability in shape among populations and provided different perspectives on patterns of geographic variation. The lateral view of the skull provided the most information content in terms of populations that share similarity in cranial shape and continuity over geographic space.

GEOGRAPHIC VARIATION IN CRANIAL MORPHOLOGY IN THRICHOMYS APEREOIDES (RODENTIA: ECHIMYIDAE). II. GEOGRAPHIC UNITS, MORPHOLOGICAL DISCONTINUITIES, AND SAMPLING GAPS

Abstract Geographic variation in cranial shape was examined in 20 samples of the echimyid rodent Thrichomys apereoides from northeastern, central, and southeastern Brazil. Canonical variate analysis and a dendrogram based on geometric shape descriptors revealed 2 groups of populations diagnosable by features of cranial shape and geographic continuity. The observed morphological discontinuity between the 2 groups of populations corresponds with a gap in sampling of T. apereoides, as represented by the museum series used. A positive, significant relationship between morphological and geographic distances was found among populations within each of the 2 groups but not between populations in the 2 groups. The indirect, statistical approach suggests that discontinuity in cranial shape in T. apereoides results from historical processes of differentiation rather than from an artifact caused by a gap in the available samples.

The New World filarial genus Molinema Freitas & Lent, 1939 (Nematoda: Onchocercidae), with a description of four new species parasitic in the Echimyidae (Rodentia).

Four new species of Molinema (Filarioidea: Onchocercidae), parasites of echimyid rodents in South America, are described: M. algardneri n. sp. from Proechimys amphichoricus, M. barbarae n. sp. from P. cayennensis, both in Venezuela (Rio Negro and Cerro La Neblina, respectively), M. peruviensis n. sp. from P. steerei in Peru (lower Urubamba), and M. nattereri n. sp. (= Filaria diacantha Molin, 1858 pro parte) from Echimys ? didelphoides (= Loncheres rufa) in Brazil (Matto Grosso). They differ from each other and from the previously described species in the following characters: flat or concave head, cephalic ratio (distance between cephalic papillae in median view/lateral view), size and shape of the buccal capsule, length of the oesophagus, cuticular ornamentation of the female body, length of the ovijector, thick or slim female tail, area rugosa, long or short filament in the left spicule, heel in the right spicule, respective position of postcloacal papilla pairs 5 and 6, shape of the caudal lappets, terminal point present or absent, and the microfilariae. Molinema, which belongs to the worldwide Dipetalonema line, is distributed in two of the ten families of the Caviomorpha (South American Hystrichognathi have extended their distribution in South America since the early Oligocene). Nine species are parasitic in the Echimyidae (suborder Caviida); they have a short oesophagus and a complete or reduced set of precloacal papillae (four or three pairs). Two species are parasitic in the Erethizontidae (Erethizontida) and might be more primitive in having a well-developed oesophagus. However, the type-species M. diacantha, of which a female specimen was studied, has a large buccal capsule and has evolved concave head, while M. arbuta has a reduced buccal capsule and primitive flat head. This last species is a parasite of a Nearctic porcupine and probably represents a small line of Molinema which migrated to the north with its hosts when communications were established between the two American continents 3 mya (Pleistocene). M. sprenti, the unique parasite of the Castoridae in North America, is considered to be derived from this group by capture.

Sounds of Neotropical Rainforest Mammals: An Audio Field Guide

L. H. Emmons, B. M. Whitney, D. L. Ross Jr. 1998. Sounds of Neotropical Rainforest Mammals: An Audio Field Guide. The University of Chicago Press, Chicago, Illinois. ISBN 0-938-02740-9, price $24.95. This compact disc set will be useful to anyone conducting field research in the Neotropics. Tropical forest mammals are more often seen than heard, and their sounds are often difficult to discern from the cacophony of sounds in a tropical forest, especially for the untrained ear. These recordings will aid both researchers and naturalists alike, whether they are experienced or not, to identify mammalian sounds of the Neotropical rainforest. The 2 compact disc set contains recordings of 109 species and subspecies of mammals: 55 nonprimates and 54 primates. These are arranged into broad taxonomic classes, which themselves are not in strict taxonomic order but are in a logical order nonetheless. Compact disc 1 (CD 1) consists of nonprimate mammals, including marsupials (number of species and subspecies recorded = 1), anteaters (3), armadillos (1), bats (3), canids (2), procyonids (6), mustelids (3), felids (3), dolphins (1), tapirs (1), peccaries (2), deer (2), manatees (2), squirrels (11), murid rodents (4), porcupines (1), capybaras (1), agoutis (2), pacas (1), and echimyid rodents (5). Compact disc 2 (CD 2) is dedicated entirely to primates and includes calls of marmosets, including Cebuella (1) and Callathrix (5); tamarins ( Saguinus ), which are divided into the saddleback group (3), the mustached group (4), and the bare-faced group (4); lion tamarins (3); Goeldi's monkeys (1); …

MAMMALS OF THE RIO JURUÁ AND THE EVOLUTIONARY AND ECOLOGICAL DIVERSIFICATION OF AMAZONIA

We describe the nonvolant mammal fauna of the Rio Juruá of the western Amazon of Brazil, based on collections made during a year-long survey of the river. We, along with our colleagues Drs. Claude Gascon and Carlos Peres, designed the field project to examine the effects of the river on the differentiation among terrestrial vertebrates (mammals, birds, and amphibians and reptiles) at both the community and population levels. This monograph examines only the patterns of geographic variation and community structure of the small-bodied mammals. Species inventories were made at 16 primary trapping localities divided into eight pairs of cross-river sites, with two pairs in each of four regions from near the mouth to the headwaters of the Rio Juruá. A total of 81 species of nonvolant mammals were obtained, including nine new to science. Four of these are described herein; the others have been described elsewhere. We used a standardized trapping protocol to assess community structure at each of the 16 localities that included terrestrial and canopy trap stations in floodplain (várzea) and upland (terra firme) forest formations. Supplemental trapping was done in secondary habitats at all sites. We describe these sites, the trap effort expended, and the placement of trap stations relative to local habitats. We also describe each species of marsupial, sciurid rodent, murid rodent, and echimyid rodent encountered; comment on their systematics; and summarize aspects of habitat use, life history, geographic distribution, and geographic differentiation based on morphological and molecular traits. We examine patterns of differentiation in the mitochondrial cytochrome-b gene for samples of 41 of the 45 species of marsupials and rodents obtained within the Rio Juruá Basin, and discuss these patterns from the perspective of the entire Amazon and, in some cases, the Mata Atlântica of coastal Brazil. We also examine patterns of community organization within the Rio Juruá basin and throughout Amazonia, drawing attention to the geographic distribution of what appear to be major faunal units that are independent of habitat differences. Finally, we use principles of phylogeography to analyze patterns of geographic differentiation among the nonvolant mammals with regard to the Riverine Barrier Hypothesis. We show that, while there are few examples of taxa for which the Rio Juruá is apparently a barrier, most taxa either are largely undifferentiated throughout the basin or are sharply divided into reciprocally monophyletic mtDNA haplotype clades separable into upriver and downriver units. We argue that the concordance in the geographic placement of clade boundaries suggests a common history; moreover, both the age of these clades and their geographic position in relation to underlying geological features suggest that landform evolution has been an important, but underappreciated component of diversification within western Amazonia.

Cranial differentiation and evolution in Thrichomys apereoides (Rodentia: Echinyidae)

Thrichomys apereoides is an echimyid rodent which ranges in distribution from north‐eastern and central Brazil into Paraguay, and currently five subspecies are recognized. Recent morphometric analyses of population samples formally assignable to T. a. laurentius and T. a. inermis, which occur in north‐eastern Brazil, have shown that a major group of populations including both subspecies differ in cranial shape from a single population allocated to T. a. laurentius. In this study we employed mathematical models of evolutionary quantitative genetics to assess the role that random drift and selection may have played in the evolution of cranial shape differences in T. apereoides. The hypothesis of evolution due to drift was rejected and the selective forces necessary to account for shape differences were estimated. Minimum selective mortalities of the order of 10‐3 of per generation were sufficient to explain the observed morphologic differentiation.

The Simultaneous Diversification of South American Echimyid Rodents (Hystricognathi) Based on Complete Cytochrome b Sequences

Variation in the complete nucleotide sequence of the mitochondrial cytochrome b gene was examined for 32 individuals representing 12 supraspecific taxa of South American rodents of the family Echimyidae (Hystricognathi). Representative genera of four other New World hystricognath families, the Old World porcupineHystrix,and the myomorph murid rodentsRattusandMuswere used as outgroups in phylogenetic reconstructions. Monophyly of the family Echimyidae is strongly supported, a result fully consistent with existing morphological and paleontological data relative to the taxa examined. However, relationships among most supraspecific taxa within the family are poorly resolved. Poor resolution appears not to result from lack of data, but to a rapid, nearly simultaneous divergence of most Recent taxa. Generic groupings that are moderately to strongly supported include the tree rats of the Brazilian Atlantic Forest (Nelomys) and Amazonia (Echimys, Makalata) and the Amazonian arboreal spiny ratsMesomysandLonchothrix.However, the two subgenera of the terrestrial spiny rats,Proechimys,do not form a monophyletic unit, and elevation of the Atlantic ForestTrinomysto generic status is supported. The genusHoplomysis closely related toProechimys(sensu stricto), a finding supported by other molecular data.