Amazonia has the richest primate fauna in the world. Nonetheless, the diversity and distribution ... more Amazonia has the richest primate fauna in the world. Nonetheless, the diversity and distribution of Amazonian primates remain little known and the scarcity of baseline data challenges their conservation. These challenges are especially acute in the Amazonian arc of deforestation, the 2500 km long southern edge of the Amazonian biome that is rapidly being deforested and converted to agricultural and pastoral landscapes. Amazonian marmosets of the genus Mico are little known endemics of this region and therefore a priority for research and conservation efforts. However, even nascent conservation efforts are hampered by taxonomic uncertainties in this group, such as the existence of a potentially new species from the Juruena–Teles Pires interfluve hidden within the M. emiliae epithet. Here we test if these marmosets belong to a distinct species using new morphological, phylogenomic, and geographic distribution data analysed within an integrative taxonomic framework. We discovered a new...
A Biota Neotropica é uma revista eletrônica e está integral e gratuitamente disponível no endereç... more A Biota Neotropica é uma revista eletrônica e está integral e gratuitamente disponível no endereço http://www.biotaneotropica.org.br Biota Neotropica is an electronic, peer-reviewed journal edited by the Program BIOTA/FAPESP: The Virtual Institute of Biodiversity. This journal's aim is to disseminate the results of original research work, associated or not to the program, concerned with characterization, conservation and sustainable use of biodiversity within the Neotropical region. Biota Neotropica é uma revista do Programa BIOTA/FAPESP-O Instituto Virtual da Biodiversidade, que publica resultados de pesquisa original, vinculada ou não ao programa, que abordem a temática caracterização, conservação e uso sustentável da biodiversidade na região Neotropical. Abstract: The impact of fire and edge effects on the community of small non-volant mammals was investigated in transitional Amazon forest within a matrix of soybean plantations. The animals were live trapped on 24 line transe...
Additional file 6: Figure S2. Ideograms showing the rearrangements among the karyotypes of six sp... more Additional file 6: Figure S2. Ideograms showing the rearrangements among the karyotypes of six species of Neacomys, as assessed based on Hylaeamys megacephalus whole chromosome probes [11]. (H) Indicates large block of constitutive heterochromatin. Karyotype abbreviations as in Table 2.
Additional file 4: Table S3. Chromosomal rearrangements among seven karyotypes of six Neacomys sp... more Additional file 4: Table S3. Chromosomal rearrangements among seven karyotypes of six Neacomys species, based on chromosome painting with Hylaeamys megacephalus probes (HME) [10].
Additional file 3: Table S2. Chromosome character data matrix of non-additive multi-state charact... more Additional file 3: Table S2. Chromosome character data matrix of non-additive multi-state character employed in the Maximum Parsimony analysis.
Additional file 2: Table S1. Non-additive multi-state character list. Character descriptions are ... more Additional file 2: Table S1. Non-additive multi-state character list. Character descriptions are detailed in Additional file 5.
The sigmodontine rodent Oecomys catherinae has been recognized as a species complex that includes... more The sigmodontine rodent Oecomys catherinae has been recognized as a species complex that includes five different lineages distributed throughout Brazil south of the Amazon river, named in literature according to their geographic position (central, eastern, northern, western, and westernmost). The western lineage also has been referred as Oecomys aff. catherinae in the literature, because it may represent a distinct species. Herein, we used molecular and morphological data to investigate the possible species distinctiveness within the O. catherinae complex. From molecular analyses, we recovered the western lineage as a monophyletic group with high genetic divergence from the other lineages of the complex. This lineage can be differentiated from other lineages of the O. catherinae complex and other congeners through a combination of mensural and morphological characters that includes: smaller size; posterior margin of nasals usually surpassing the maxillary–frontal suture; supraorbita...
Rhipidomys (Sigmodontinae, Thomasomyini) has 25 recognized species, with a wide distribution rang... more Rhipidomys (Sigmodontinae, Thomasomyini) has 25 recognized species, with a wide distribution ranging from eastern Panama to northern Argentina. Cytogenetic data has been described for 13 species with 12 of them having 2n = 44 with a high level of autosomal fundamental number (FN) variation, ranging from 46 to 80, assigned to pericentric inversions. The species are grouped in groups with low FN (46–52) and high FN (72–80). In this work the karyotypes of Rhipidomys emiliae (2n = 44, FN = 50) and Rhipidomys mastacalis (2n = 44, FN = 74), were studied by classical cytogenetics and by fluorescence in situ hybridization using telomeric and whole chromosome probes (chromosome painting) of Hylaeamys megacephalus (HME). Chromosome painting revealed homology between 36 segments of REM and 37 of RMA. We tested the hypothesis that pericentric inversions are the predominant chromosomal rearrangements responsible for karyotypic divergence between these species, as proposed in literature. Our resu...
The phylogeny of tits has been studied using various molecular markers, but their phylogenetic re... more The phylogeny of tits has been studied using various molecular markers, but their phylogenetic relationships remain controversial. To further investigate their taxonomic status and phylogenetic relationships, the entire mitochondrial genomes (mitogenomes) and five nuclear segments were sequenced from 10 species of tits and two outgroups (Sylviparus modestus and Remiz consobrinus), followed by the comparison of mitogenomic characteristics and reconstruction of phylogenetic relationship based on the different datasets. The results revealed the following: the mitogenomes of 10 ingroup tits, each 16,768-16,800 bp in length, displayed typical mitogenome organization and the gene order found in most previously determined Passeriformes mitogenomes; close relationships existed between Parus major and P. monticolus, between P. montanus and P. palustris, and between P. ater and P. venustulus; and Pseudopodoces humilis was a sister group to P. spilonotus, P. cyanus, or the clade containing P. major and P. monticolus.
To resolve phylogenetic relationships among species of Marmosa we analyzed DNA sequences from one... more To resolve phylogenetic relationships among species of Marmosa we analyzed DNA sequences from one mitochondrial and three nuclear genes for every member of the nomino-typical subgenus and from four species of the subgenus Micoureus. As reported in previous studies, the subgenus Marmosa was found to be paraphyletic, whereas Micoureus was recovered as a robustly supported clade. Species currently referred to the subgenus Marmosa form four strongly supported and morphologically diagnosable groups. Based on these results we recognize a total of five subgenera: Marmosa Gray, 1821 (for macrotarsus, murina, tyleriana, and waterhousei); Micoureus Lesson, 1842 (for alstoni, constantiae, demerarae, paraguayana, phaea, and regina); Stegomarmosa Pine, 1972 (for andersoni and lepida); Eomarmosa, new subgenus (for rubra); and Exulomarmosa, new subgenus (for isthmica, mexicana, robinsoni, simonsi, xerophila, and zeledoni). The best-supported hypothesis of relationships among these clades is 1 Divi...
Rhipidomys (Sigmodontinae, Thomasomyini) has 25 recognized species, with a wide distribution rang... more Rhipidomys (Sigmodontinae, Thomasomyini) has 25 recognized species, with a wide distribution ranging from eastern Panama to northern Argentina. Cytogenetic data has been described for 13 species with 12 of them having 2n = 44 with a high level of autosomal fundamental number (FN) variation, ranging from 46 to 80, assigned to pericentric inversions. The species are grouped in groups with low FN (46–52) and high FN (72–80). In this work the karyotypes of Rhipidomys emiliae (2n = 44, FN = 50) and Rhipidomys mastacalis (2n = 44, FN = 74), were studied by classical cytogenetics and by fluorescence in situ hybridization using telomeric and whole chromosome probes (chromosome painting) of Hylaeamys megacephalus (HME). Chromosome painting revealed homology between 36 segments of REM and 37 of RMA. We tested the hypothesis that pericentric inversions are the predominant chromosomal rearrangements responsible for karyotypic divergence between these species, as proposed in literature. Our resu...
The genus Marmosops comprises small marsupials of the family Didelphidae (≤ 200 g), widely distri... more The genus Marmosops comprises small marsupials of the family Didelphidae (≤ 200 g), widely distributed in a variety of lowland rainforest and montane forest habitats, extending from Panama to southern Bolivia and southeastern Brazil. The smallest species of the genus are included in the “Parvidens” group, which includes M. pakaraimae, M. parvidens and M. pinheiroi. Although the monophyly of this group and species relationships are well defined, molecular studies have indicated that M. pinheiroi may represent a species complex, which has never been tested based on morphological analysis. In this study, we present the taxonomic review of M. pinheiroi based on the largest sample ever analyzed of this species. The external and craniodental morphology of 613 specimens of M. parvidens and M. pinheiroi from the northern, eastern, central and southern Brazilian Amazonia and northern Cerrado were examined. Besides, 28 craniodental dimensions were measured from adult specimens to support univ...
In the present study, samples of tick, tissue and blood from free-living wild small mammals (rode... more In the present study, samples of tick, tissue and blood from free-living wild small mammals (rodents and marsupials) captured in two municipalities from the Amazon biome of the Mato Grosso state, were molecularly tested for rickettsial infection. A total of 148 mammal specimens (46 rodents and 102 marsupials) were trapped, and 2,700 Amblyomma ticks (2,000 larvae and 700 nymphs) were collected. Ticks were recognized into four Amblyomma species: Amblyomma cajennense sensu stricto, Amblyomma coelebs, Amblyomma humerale, and Amblyomma scalpturatum, with new data for tick-host associations from small mammals in the Amazon biome. All tissue and blood samples of small mammals tested by PCR for rickettsial detection were negative. However, concerning tick-Rickettsia associations, Rickettsia amblyommatis was detected in all four tick species identified in the present study, being the first record for A. scalpturatum ticks. Furthermore, an uncharacterized species of Rickettsia belonging to th...
Small non-volant mammals (marsupials and small rodents) were captured at three different timepoin... more Small non-volant mammals (marsupials and small rodents) were captured at three different timepoints from 23 forest fragments across three municipalities (Alta Floresta, Sinop and Cláudia) covering the Amazonian biome of the Mato Grosso State in Midwestern Brazil. The animal tissues (liver and spleen) and blood were screened using molecular tools for the detection of Babesia, Coxiella, Cytauxzoon, Hepatozoon, Theileria, and Anaplasmataceae agents. A total of 230 specimens (78 rodents and 152 marsupials) were trapped. Hepatozoon and Piroplasmorida agents were detected in the common opossums (Didelphis marsupialis). In turn, all samples (blood, liver, or spleen) collected from the small mammals were negative for the genus Coxiella and the family Anaplasmataceae, as detected by polymerase chain reaction (PCR). Phylogenetic analyses inferred from partial sequences of the 18S rRNA gene highlighted the occurrence of new Hepatozoon and Piroplasmorida haplotypes. Future studies determining t...
Background: The Neacomys genus is predominantly found in the Amazon region, and belongs to the mo... more Background: The Neacomys genus is predominantly found in the Amazon region, and belongs to the most diverse tribe of the Sigmodontinae subfamily (Rodentia, Cricetidae, Oryzomyini). The systematics of this genus and questions about its diversity and range have been investigated by morphological, molecular (Cytb and COI sequences) and karyotype analysis (classic cytogenetics and chromosome painting), which have revealed candidate species and new distribution areas. Here we analyzed four species of Neacomys by chromosome painting with Hylaeamys megacephalus (HME) whole-chromosome probes, and compared the results with two previously studied Neacomys species and with other taxa from Oryzomyini and Akodontini tribes that have been hybridized with HME probes. Maximum Parsimony (MP) analyses were performed with the PAUP and T.N.T. software packages, using a non-additive (unordered) multi-state character matrix, based on chromosomal morphology, number and syntenic blocks. We also compared the chromosomal phylogeny obtained in this study with molecular topologies (Cytb and COI) that included eastern Amazonian species of Neacomys, to define the phylogenetic relationships of these taxa. Results: The comparative chromosome painting analysis of the seven karyotypes of the six species of Neacomys shows that their diversity is due to 17 fusion/fission events and one translocation, pericentric inversions in four syntenic blocks, and constitutive heterochromatin (CH) amplification/deletion of six syntenic autosomal blocks plus the X chromosome. The chromosomal phylogeny is consistent with the molecular relationships of species of Neacomys. We describe new karyotypes and expand the distribution area for species from eastern Amazonia and detect complex rearrangements by chromosome painting among the karyotypes. Conclusions: Our phylogeny reflects the molecular relationships of the Akodontini and Oryzomyini taxa and supports the monophyly of Neacomys. This work presents new insights about the chromosomal evolution of this group, and we conclude that the karyotypic divergence is in accord with phylogenetic relationships.
Oecomys tapajinus (Tapajós Oecomys) is currently a junior synonym of Oecomys roberti (Robert's Oe... more Oecomys tapajinus (Tapajós Oecomys) is currently a junior synonym of Oecomys roberti (Robert's Oecomys), a widely distributed Amazonian mouse, which probably represents a complex of cryptic species. We investigated the taxonomic status of O. tapajinus by integrating phylogenetic analyses of DNA sequences and morphological analyses of museum specimens. We were able to confirm that O. tapajinus is a valid species from eastern Amazonia and the transition to the Brazilian Cerrado, where it is sympatric with O. roberti. Oecomys tapajinus is characterized by a unique combination of morphological traits, high morphological variation, and genetic differentiation and structure related to the complex system of the Amazon River. Potential additional entities within the O. roberti complex emerged from our analyses, and further investigation with larger series may shed light on the taxonomic status of this species complex. Oecomys tapajinus (rato-da-árvore do Tapajós) é atualmente considerado um sinónimo júnior de Oecomys roberti (rato-da-árvore de Robert), um roedor amplamente distribuído na Amazônia, e que provavelmente representa um complexo de espécies crípticas. Neste trabalho investigamos o status taxonômico de O. tapajinus, integrando análises filogenéticas de sequências de ADN e análises morfológicas de espécimes de museus. Confirmamos o status de O. tapajinus como uma espécie válida que ocorre no este da Amazônia e na transição com o Cerrado Brasileiro, onde é simpátrico com O. roberti. Oecomys tapajinus é caracterizado por uma combinação única de caracteres morfológicos, uma alta variação morfológica, e uma diferenciação e estrutura genética associada ao sistema complexo do Rio Amazonas. Este trabalho também revelou outras potenciais unidades dentro do complexo O. roberti que merecem investigação adicional com maiores séries amostrais e que irão ajudar a clarificar o status taxonômico deste complexo de espécies.
Amazonia has the richest primate fauna in the world. Nonetheless, the diversity and distribution ... more Amazonia has the richest primate fauna in the world. Nonetheless, the diversity and distribution of Amazonian primates remain little known and the scarcity of baseline data challenges their conservation. These challenges are especially acute in the Amazonian arc of deforestation, the 2500 km long southern edge of the Amazonian biome that is rapidly being deforested and converted to agricultural and pastoral landscapes. Amazonian marmosets of the genus Mico are little known endemics of this region and therefore a priority for research and conservation efforts. However, even nascent conservation efforts are hampered by taxonomic uncertainties in this group, such as the existence of a potentially new species from the Juruena–Teles Pires interfluve hidden within the M. emiliae epithet. Here we test if these marmosets belong to a distinct species using new morphological, phylogenomic, and geographic distribution data analysed within an integrative taxonomic framework. We discovered a new...
A Biota Neotropica é uma revista eletrônica e está integral e gratuitamente disponível no endereç... more A Biota Neotropica é uma revista eletrônica e está integral e gratuitamente disponível no endereço http://www.biotaneotropica.org.br Biota Neotropica is an electronic, peer-reviewed journal edited by the Program BIOTA/FAPESP: The Virtual Institute of Biodiversity. This journal's aim is to disseminate the results of original research work, associated or not to the program, concerned with characterization, conservation and sustainable use of biodiversity within the Neotropical region. Biota Neotropica é uma revista do Programa BIOTA/FAPESP-O Instituto Virtual da Biodiversidade, que publica resultados de pesquisa original, vinculada ou não ao programa, que abordem a temática caracterização, conservação e uso sustentável da biodiversidade na região Neotropical. Abstract: The impact of fire and edge effects on the community of small non-volant mammals was investigated in transitional Amazon forest within a matrix of soybean plantations. The animals were live trapped on 24 line transe...
Additional file 6: Figure S2. Ideograms showing the rearrangements among the karyotypes of six sp... more Additional file 6: Figure S2. Ideograms showing the rearrangements among the karyotypes of six species of Neacomys, as assessed based on Hylaeamys megacephalus whole chromosome probes [11]. (H) Indicates large block of constitutive heterochromatin. Karyotype abbreviations as in Table 2.
Additional file 4: Table S3. Chromosomal rearrangements among seven karyotypes of six Neacomys sp... more Additional file 4: Table S3. Chromosomal rearrangements among seven karyotypes of six Neacomys species, based on chromosome painting with Hylaeamys megacephalus probes (HME) [10].
Additional file 3: Table S2. Chromosome character data matrix of non-additive multi-state charact... more Additional file 3: Table S2. Chromosome character data matrix of non-additive multi-state character employed in the Maximum Parsimony analysis.
Additional file 2: Table S1. Non-additive multi-state character list. Character descriptions are ... more Additional file 2: Table S1. Non-additive multi-state character list. Character descriptions are detailed in Additional file 5.
The sigmodontine rodent Oecomys catherinae has been recognized as a species complex that includes... more The sigmodontine rodent Oecomys catherinae has been recognized as a species complex that includes five different lineages distributed throughout Brazil south of the Amazon river, named in literature according to their geographic position (central, eastern, northern, western, and westernmost). The western lineage also has been referred as Oecomys aff. catherinae in the literature, because it may represent a distinct species. Herein, we used molecular and morphological data to investigate the possible species distinctiveness within the O. catherinae complex. From molecular analyses, we recovered the western lineage as a monophyletic group with high genetic divergence from the other lineages of the complex. This lineage can be differentiated from other lineages of the O. catherinae complex and other congeners through a combination of mensural and morphological characters that includes: smaller size; posterior margin of nasals usually surpassing the maxillary–frontal suture; supraorbita...
Rhipidomys (Sigmodontinae, Thomasomyini) has 25 recognized species, with a wide distribution rang... more Rhipidomys (Sigmodontinae, Thomasomyini) has 25 recognized species, with a wide distribution ranging from eastern Panama to northern Argentina. Cytogenetic data has been described for 13 species with 12 of them having 2n = 44 with a high level of autosomal fundamental number (FN) variation, ranging from 46 to 80, assigned to pericentric inversions. The species are grouped in groups with low FN (46–52) and high FN (72–80). In this work the karyotypes of Rhipidomys emiliae (2n = 44, FN = 50) and Rhipidomys mastacalis (2n = 44, FN = 74), were studied by classical cytogenetics and by fluorescence in situ hybridization using telomeric and whole chromosome probes (chromosome painting) of Hylaeamys megacephalus (HME). Chromosome painting revealed homology between 36 segments of REM and 37 of RMA. We tested the hypothesis that pericentric inversions are the predominant chromosomal rearrangements responsible for karyotypic divergence between these species, as proposed in literature. Our resu...
The phylogeny of tits has been studied using various molecular markers, but their phylogenetic re... more The phylogeny of tits has been studied using various molecular markers, but their phylogenetic relationships remain controversial. To further investigate their taxonomic status and phylogenetic relationships, the entire mitochondrial genomes (mitogenomes) and five nuclear segments were sequenced from 10 species of tits and two outgroups (Sylviparus modestus and Remiz consobrinus), followed by the comparison of mitogenomic characteristics and reconstruction of phylogenetic relationship based on the different datasets. The results revealed the following: the mitogenomes of 10 ingroup tits, each 16,768-16,800 bp in length, displayed typical mitogenome organization and the gene order found in most previously determined Passeriformes mitogenomes; close relationships existed between Parus major and P. monticolus, between P. montanus and P. palustris, and between P. ater and P. venustulus; and Pseudopodoces humilis was a sister group to P. spilonotus, P. cyanus, or the clade containing P. major and P. monticolus.
To resolve phylogenetic relationships among species of Marmosa we analyzed DNA sequences from one... more To resolve phylogenetic relationships among species of Marmosa we analyzed DNA sequences from one mitochondrial and three nuclear genes for every member of the nomino-typical subgenus and from four species of the subgenus Micoureus. As reported in previous studies, the subgenus Marmosa was found to be paraphyletic, whereas Micoureus was recovered as a robustly supported clade. Species currently referred to the subgenus Marmosa form four strongly supported and morphologically diagnosable groups. Based on these results we recognize a total of five subgenera: Marmosa Gray, 1821 (for macrotarsus, murina, tyleriana, and waterhousei); Micoureus Lesson, 1842 (for alstoni, constantiae, demerarae, paraguayana, phaea, and regina); Stegomarmosa Pine, 1972 (for andersoni and lepida); Eomarmosa, new subgenus (for rubra); and Exulomarmosa, new subgenus (for isthmica, mexicana, robinsoni, simonsi, xerophila, and zeledoni). The best-supported hypothesis of relationships among these clades is 1 Divi...
Rhipidomys (Sigmodontinae, Thomasomyini) has 25 recognized species, with a wide distribution rang... more Rhipidomys (Sigmodontinae, Thomasomyini) has 25 recognized species, with a wide distribution ranging from eastern Panama to northern Argentina. Cytogenetic data has been described for 13 species with 12 of them having 2n = 44 with a high level of autosomal fundamental number (FN) variation, ranging from 46 to 80, assigned to pericentric inversions. The species are grouped in groups with low FN (46–52) and high FN (72–80). In this work the karyotypes of Rhipidomys emiliae (2n = 44, FN = 50) and Rhipidomys mastacalis (2n = 44, FN = 74), were studied by classical cytogenetics and by fluorescence in situ hybridization using telomeric and whole chromosome probes (chromosome painting) of Hylaeamys megacephalus (HME). Chromosome painting revealed homology between 36 segments of REM and 37 of RMA. We tested the hypothesis that pericentric inversions are the predominant chromosomal rearrangements responsible for karyotypic divergence between these species, as proposed in literature. Our resu...
The genus Marmosops comprises small marsupials of the family Didelphidae (≤ 200 g), widely distri... more The genus Marmosops comprises small marsupials of the family Didelphidae (≤ 200 g), widely distributed in a variety of lowland rainforest and montane forest habitats, extending from Panama to southern Bolivia and southeastern Brazil. The smallest species of the genus are included in the “Parvidens” group, which includes M. pakaraimae, M. parvidens and M. pinheiroi. Although the monophyly of this group and species relationships are well defined, molecular studies have indicated that M. pinheiroi may represent a species complex, which has never been tested based on morphological analysis. In this study, we present the taxonomic review of M. pinheiroi based on the largest sample ever analyzed of this species. The external and craniodental morphology of 613 specimens of M. parvidens and M. pinheiroi from the northern, eastern, central and southern Brazilian Amazonia and northern Cerrado were examined. Besides, 28 craniodental dimensions were measured from adult specimens to support univ...
In the present study, samples of tick, tissue and blood from free-living wild small mammals (rode... more In the present study, samples of tick, tissue and blood from free-living wild small mammals (rodents and marsupials) captured in two municipalities from the Amazon biome of the Mato Grosso state, were molecularly tested for rickettsial infection. A total of 148 mammal specimens (46 rodents and 102 marsupials) were trapped, and 2,700 Amblyomma ticks (2,000 larvae and 700 nymphs) were collected. Ticks were recognized into four Amblyomma species: Amblyomma cajennense sensu stricto, Amblyomma coelebs, Amblyomma humerale, and Amblyomma scalpturatum, with new data for tick-host associations from small mammals in the Amazon biome. All tissue and blood samples of small mammals tested by PCR for rickettsial detection were negative. However, concerning tick-Rickettsia associations, Rickettsia amblyommatis was detected in all four tick species identified in the present study, being the first record for A. scalpturatum ticks. Furthermore, an uncharacterized species of Rickettsia belonging to th...
Small non-volant mammals (marsupials and small rodents) were captured at three different timepoin... more Small non-volant mammals (marsupials and small rodents) were captured at three different timepoints from 23 forest fragments across three municipalities (Alta Floresta, Sinop and Cláudia) covering the Amazonian biome of the Mato Grosso State in Midwestern Brazil. The animal tissues (liver and spleen) and blood were screened using molecular tools for the detection of Babesia, Coxiella, Cytauxzoon, Hepatozoon, Theileria, and Anaplasmataceae agents. A total of 230 specimens (78 rodents and 152 marsupials) were trapped. Hepatozoon and Piroplasmorida agents were detected in the common opossums (Didelphis marsupialis). In turn, all samples (blood, liver, or spleen) collected from the small mammals were negative for the genus Coxiella and the family Anaplasmataceae, as detected by polymerase chain reaction (PCR). Phylogenetic analyses inferred from partial sequences of the 18S rRNA gene highlighted the occurrence of new Hepatozoon and Piroplasmorida haplotypes. Future studies determining t...
Background: The Neacomys genus is predominantly found in the Amazon region, and belongs to the mo... more Background: The Neacomys genus is predominantly found in the Amazon region, and belongs to the most diverse tribe of the Sigmodontinae subfamily (Rodentia, Cricetidae, Oryzomyini). The systematics of this genus and questions about its diversity and range have been investigated by morphological, molecular (Cytb and COI sequences) and karyotype analysis (classic cytogenetics and chromosome painting), which have revealed candidate species and new distribution areas. Here we analyzed four species of Neacomys by chromosome painting with Hylaeamys megacephalus (HME) whole-chromosome probes, and compared the results with two previously studied Neacomys species and with other taxa from Oryzomyini and Akodontini tribes that have been hybridized with HME probes. Maximum Parsimony (MP) analyses were performed with the PAUP and T.N.T. software packages, using a non-additive (unordered) multi-state character matrix, based on chromosomal morphology, number and syntenic blocks. We also compared the chromosomal phylogeny obtained in this study with molecular topologies (Cytb and COI) that included eastern Amazonian species of Neacomys, to define the phylogenetic relationships of these taxa. Results: The comparative chromosome painting analysis of the seven karyotypes of the six species of Neacomys shows that their diversity is due to 17 fusion/fission events and one translocation, pericentric inversions in four syntenic blocks, and constitutive heterochromatin (CH) amplification/deletion of six syntenic autosomal blocks plus the X chromosome. The chromosomal phylogeny is consistent with the molecular relationships of species of Neacomys. We describe new karyotypes and expand the distribution area for species from eastern Amazonia and detect complex rearrangements by chromosome painting among the karyotypes. Conclusions: Our phylogeny reflects the molecular relationships of the Akodontini and Oryzomyini taxa and supports the monophyly of Neacomys. This work presents new insights about the chromosomal evolution of this group, and we conclude that the karyotypic divergence is in accord with phylogenetic relationships.
Oecomys tapajinus (Tapajós Oecomys) is currently a junior synonym of Oecomys roberti (Robert's Oe... more Oecomys tapajinus (Tapajós Oecomys) is currently a junior synonym of Oecomys roberti (Robert's Oecomys), a widely distributed Amazonian mouse, which probably represents a complex of cryptic species. We investigated the taxonomic status of O. tapajinus by integrating phylogenetic analyses of DNA sequences and morphological analyses of museum specimens. We were able to confirm that O. tapajinus is a valid species from eastern Amazonia and the transition to the Brazilian Cerrado, where it is sympatric with O. roberti. Oecomys tapajinus is characterized by a unique combination of morphological traits, high morphological variation, and genetic differentiation and structure related to the complex system of the Amazon River. Potential additional entities within the O. roberti complex emerged from our analyses, and further investigation with larger series may shed light on the taxonomic status of this species complex. Oecomys tapajinus (rato-da-árvore do Tapajós) é atualmente considerado um sinónimo júnior de Oecomys roberti (rato-da-árvore de Robert), um roedor amplamente distribuído na Amazônia, e que provavelmente representa um complexo de espécies crípticas. Neste trabalho investigamos o status taxonômico de O. tapajinus, integrando análises filogenéticas de sequências de ADN e análises morfológicas de espécimes de museus. Confirmamos o status de O. tapajinus como uma espécie válida que ocorre no este da Amazônia e na transição com o Cerrado Brasileiro, onde é simpátrico com O. roberti. Oecomys tapajinus é caracterizado por uma combinação única de caracteres morfológicos, uma alta variação morfológica, e uma diferenciação e estrutura genética associada ao sistema complexo do Rio Amazonas. Este trabalho também revelou outras potenciais unidades dentro do complexo O. roberti que merecem investigação adicional com maiores séries amostrais e que irão ajudar a clarificar o status taxonômico deste complexo de espécies.
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