A new species of Echimys Cuvier, 1809 (Rodentia, Echimyidae) from Brazil

Abstract

Here we describe a new species of Echimyidae Amazonian rodent, Echimys vieirai sp. nov., based on two individuals from the south bank of Amazon river between the lower Madeira river to the right bank of the Tapajós, respectively in the Brazilian states of Amazonas and Pará, Brazil. The main diagnostic characteristic of this new species is the presence of a dorsal median dark maroon stripe on the head, running from the rostrum to the nape. Skull morphology is quite similar to that of Echimys chrysurus (Zimmermann, 1780), but our new species differ from other species in the genus by the development of the alisphenoid canal and dp4 morphology. Additionally, we offer a refinement of the diagnosis of the genera Echimys and Makalata.<br>É apresentada a descrição de uma nova espécie de Echimyidae, Echimys vieirai sp. nov., baseado em dois espécimens coletados em Barreirinha, rio Tapajós, Pará e Virgem Guajará, Amazonas. A principal característica diagnóstica desta nova espécie é a presença de uma faixa mediana marrom na cabeça que se extende do dorso até a nuca. A morfologia do crânio é similar a de Echimys chrysurus (Zimmermann, 1780), e difere das demais espécies do gênero em relação ao desenvolvimento do canal do alisfenóide e a morfologia do dp4. É apresentado também uma nova diagnose do gênero Echimys e um refinamento da diagnose dos gênero Makalata

The mammalian faunas endemic to the Cerrado and the Caatinga

“…These aspects strongly suggest that minor and albispinus do not constitute different subspecies of a single species, but rather that they are valid biological species, able to maintain their morphological differences in close geographic proximity and in absence of barriers to dispersal (i.e., virtually in sympatry) – even if they share the same karyotype and shallow genetic divergences. According to Pessôa et al (2015b), Iack-Ximenes (2005 [an unpublished Ph.D. dissertation]) also recommends treating Trinomys minor as a species rather than as a subspecies of Trinomys albispinus . A number of potential causes could explain the yet-to-be-confirmed topology described in the species account by Pessôa et al (2015b), including incomplete lineage sorting and other more technical aspects of the analyses and/or data (e.g., saturation of sequences, biases in nucleotide composition).…”

“…3.1 has not yet attempted to evaluate the extinction risk of Trinomys minor , and although the IUCN acknowledged that the Iack-Ximenes’s (2005) unpublished Ph.D. dissertation concluded that minor merited species-level recognition, it treated minor as a subspecies of Trinomys albispinus (see Bonvicino et al 2016). The species was not included in the official list of threatened species of Brazil (ICMBIO-MMA 2016).…”

The mammalian faunas endemic to the Cerrado and the Caatinga

“…These aspects strongly suggest that minor and albispinus do not constitute different subspecies of a single species, but rather that they are valid biological species, able to maintain their morphological differences in close geographic proximity and in absence of barriers to dispersal (i.e., virtually in sympatry) – even if they share the same karyotype and shallow genetic divergences. According to Pessôa et al (2015b), Iack-Ximenes (2005 [an unpublished Ph.D. dissertation]) also recommends treating Trinomys minor as a species rather than as a subspecies of Trinomys albispinus . A number of potential causes could explain the yet-to-be-confirmed topology described in the species account by Pessôa et al (2015b), including incomplete lineage sorting and other more technical aspects of the analyses and/or data (e.g., saturation of sequences, biases in nucleotide composition).…”

“…3.1 has not yet attempted to evaluate the extinction risk of Trinomys minor , and although the IUCN acknowledged that the Iack-Ximenes’s (2005) unpublished Ph.D. dissertation concluded that minor merited species-level recognition, it treated minor as a subspecies of Trinomys albispinus (see Bonvicino et al 2016). The species was not included in the official list of threatened species of Brazil (ICMBIO-MMA 2016).…”

First records of Echimys saturnus Thomas, 1928 (Rodentia, Echimyidae) for the Peruvian Yungas

“…To date, the only morphological measurements that have been documented on this species are those of the type specimen (Thomas 1928;Iack-Ximenes et al 2005). This lack of data from other individuals limits our understanding of age, sex, and population variability; therefore, our study enriches the description of E. saturnus by adding new measures, both external and craniodental, of two individuals of this species from montane forests populations, one of them being a subadult female.…”

“…These measurements and their definitions are as follow: greatest skull length (GSL), anterior-most projection of nasals to posteriormost projection of occipital region on midline of skull; nasal length (NL), greatest length of nasals at midline; rostral length (RL), diagonal distance from anterior edge of orbit lateral to lacrimal to anterior edge of nasals at midline; orbital length (OL), greatest length of orbits; rostral breadth (RB), breadth of rostrum at the suture between premaxilla and maxilla; interorbital constriction (IOC), least distance between bony orbits; mastoid breadth (MB), distance across cranium at mastoid processes; zygomatic breadth (ZB), maximum width across outside margins of zygomatic arches; condyloincisive length (CIL), anterior edge of upper incisors to posterior-most projection of occipital condyle; basilar length (BaL), posterior margins of upper incisors to anterior edge of foramen magnum; diastema length (D), posterior alveolar margin of upper incisors to anterior alveolar edge of PM4; maxillary toothrow length (MTRL), anterior alveolar edge of PM4 to posterior alveolar edge of M3; palatal length a (PLa), midline distance between posterior margins of upper incisors to anterior margin of mesopterygoid fossa; palatal length b (PLb), anterior edge of PM4 to anterior edge of mesopterygoid fossa; incisive foramina length (IFL), length of opening of foramina; bullar length (BuL), maximal distance from anterior to posterior edges of tympanic bulla; postpalatal length (PPL), posterior margin of inner aspect of zygomatic arch to a line perpendicular and tangent to greatest projection of occipital region; mesopterygoid fossa width (MPF), maximum width taken at the suture between palatine and pterygoid bones; first molar breath (M1B), greatest distance from lingual to buccal borders of crown; maxillary breadth (MaxB), greatest breadth of maxilla on outside of M3; occipital condyle width (OccW), width across outside margins of the occipital condyles; rostral depth (RD), depth of rostrum at the suture between premaxilla and maxilla; mandible length (MBL), from the lingual border of the incisors' alveoli to the posteriormost border of the postcondyloid process; mandible height (MH), shortest distance taken vertically from the uppermost part of the condyloid process to a plane passing from the lower edge of the symphiseal suture to the lowermost edge of the angular process; cranial depth (CD), vertical distance from ventral margin of bulla to top of cranium; cranial depth at M1 (CDM1). The measurements of the holotype were taken from Thomas (1928) and Iack-Ximenes et al (2005). In addition, we compared our specimens with photographs from…”

“…Emmons (2005),Iack-Ximenes et al (2005),Blake et al (2010),Emmons et al (2015), andMosquera et al (2016).…”

The mammalian faunas endemic to the Cerrado and the Caatinga

“…These aspects strongly suggest that minor and albispinus do not constitute different subspecies of a single species, but rather that they are valid biological species, able to maintain their morphological differences in close geographic proximity and in absence of barriers to dispersal (i.e., virtually in sympatry) – even if they share the same karyotype and shallow genetic divergences. According to Pessôa et al (2015b), Iack-Ximenes (2005 [an unpublished Ph.D. dissertation]) also recommends treating Trinomys minor as a species rather than as a subspecies of Trinomys albispinus . A number of potential causes could explain the yet-to-be-confirmed topology described in the species account by Pessôa et al (2015b), including incomplete lineage sorting and other more technical aspects of the analyses and/or data (e.g., saturation of sequences, biases in nucleotide composition).…”

“…3.1 has not yet attempted to evaluate the extinction risk of Trinomys minor , and although the IUCN acknowledged that the Iack-Ximenes’s (2005) unpublished Ph.D. dissertation concluded that minor merited species-level recognition, it treated minor as a subspecies of Trinomys albispinus (see Bonvicino et al 2016). The species was not included in the official list of threatened species of Brazil (ICMBIO-MMA 2016).…”

First records of Echimys saturnus Thomas, 1928 (Rodentia, Echimyidae) for the Peruvian Yungas

“…To date, the only morphological measurements that have been documented on this species are those of the type specimen (Thomas 1928;Iack-Ximenes et al 2005). This lack of data from other individuals limits our understanding of age, sex, and population variability; therefore, our study enriches the description of E. saturnus by adding new measures, both external and craniodental, of two individuals of this species from montane forests populations, one of them being a subadult female.…”

“…These measurements and their definitions are as follow: greatest skull length (GSL), anterior-most projection of nasals to posteriormost projection of occipital region on midline of skull; nasal length (NL), greatest length of nasals at midline; rostral length (RL), diagonal distance from anterior edge of orbit lateral to lacrimal to anterior edge of nasals at midline; orbital length (OL), greatest length of orbits; rostral breadth (RB), breadth of rostrum at the suture between premaxilla and maxilla; interorbital constriction (IOC), least distance between bony orbits; mastoid breadth (MB), distance across cranium at mastoid processes; zygomatic breadth (ZB), maximum width across outside margins of zygomatic arches; condyloincisive length (CIL), anterior edge of upper incisors to posterior-most projection of occipital condyle; basilar length (BaL), posterior margins of upper incisors to anterior edge of foramen magnum; diastema length (D), posterior alveolar margin of upper incisors to anterior alveolar edge of PM4; maxillary toothrow length (MTRL), anterior alveolar edge of PM4 to posterior alveolar edge of M3; palatal length a (PLa), midline distance between posterior margins of upper incisors to anterior margin of mesopterygoid fossa; palatal length b (PLb), anterior edge of PM4 to anterior edge of mesopterygoid fossa; incisive foramina length (IFL), length of opening of foramina; bullar length (BuL), maximal distance from anterior to posterior edges of tympanic bulla; postpalatal length (PPL), posterior margin of inner aspect of zygomatic arch to a line perpendicular and tangent to greatest projection of occipital region; mesopterygoid fossa width (MPF), maximum width taken at the suture between palatine and pterygoid bones; first molar breath (M1B), greatest distance from lingual to buccal borders of crown; maxillary breadth (MaxB), greatest breadth of maxilla on outside of M3; occipital condyle width (OccW), width across outside margins of the occipital condyles; rostral depth (RD), depth of rostrum at the suture between premaxilla and maxilla; mandible length (MBL), from the lingual border of the incisors' alveoli to the posteriormost border of the postcondyloid process; mandible height (MH), shortest distance taken vertically from the uppermost part of the condyloid process to a plane passing from the lower edge of the symphiseal suture to the lowermost edge of the angular process; cranial depth (CD), vertical distance from ventral margin of bulla to top of cranium; cranial depth at M1 (CDM1). The measurements of the holotype were taken from Thomas (1928) and Iack-Ximenes et al (2005). In addition, we compared our specimens with photographs from…”

“…Emmons (2005),Iack-Ximenes et al (2005),Blake et al (2010),Emmons et al (2015), andMosquera et al (2016).…”

The mammalian faunas endemic to the Cerrado and the Caatinga

“…These aspects strongly suggest that minor and albispinus do not constitute different subspecies of a single species, but rather that they are valid biological species, able to maintain their morphological differences in close geographic proximity and in absence of barriers to dispersal (i.e., virtually in sympatry) – even if they share the same karyotype and shallow genetic divergences. According to Pessôa et al (2015b), Iack-Ximenes (2005 [an unpublished Ph.D. dissertation]) also recommends treating Trinomys minor as a species rather than as a subspecies of Trinomys albispinus . A number of potential causes could explain the yet-to-be-confirmed topology described in the species account by Pessôa et al (2015b), including incomplete lineage sorting and other more technical aspects of the analyses and/or data (e.g., saturation of sequences, biases in nucleotide composition).…”

“…3.1 has not yet attempted to evaluate the extinction risk of Trinomys minor , and although the IUCN acknowledged that the Iack-Ximenes’s (2005) unpublished Ph.D. dissertation concluded that minor merited species-level recognition, it treated minor as a subspecies of Trinomys albispinus (see Bonvicino et al 2016). The species was not included in the official list of threatened species of Brazil (ICMBIO-MMA 2016).…”

First records of Echimys saturnus Thomas, 1928 (Rodentia, Echimyidae) for the Peruvian Yungas

“…To date, the only morphological measurements that have been documented on this species are those of the type specimen (Thomas 1928;Iack-Ximenes et al 2005). This lack of data from other individuals limits our understanding of age, sex, and population variability; therefore, our study enriches the description of E. saturnus by adding new measures, both external and craniodental, of two individuals of this species from montane forests populations, one of them being a subadult female.…”

“…These measurements and their definitions are as follow: greatest skull length (GSL), anterior-most projection of nasals to posteriormost projection of occipital region on midline of skull; nasal length (NL), greatest length of nasals at midline; rostral length (RL), diagonal distance from anterior edge of orbit lateral to lacrimal to anterior edge of nasals at midline; orbital length (OL), greatest length of orbits; rostral breadth (RB), breadth of rostrum at the suture between premaxilla and maxilla; interorbital constriction (IOC), least distance between bony orbits; mastoid breadth (MB), distance across cranium at mastoid processes; zygomatic breadth (ZB), maximum width across outside margins of zygomatic arches; condyloincisive length (CIL), anterior edge of upper incisors to posterior-most projection of occipital condyle; basilar length (BaL), posterior margins of upper incisors to anterior edge of foramen magnum; diastema length (D), posterior alveolar margin of upper incisors to anterior alveolar edge of PM4; maxillary toothrow length (MTRL), anterior alveolar edge of PM4 to posterior alveolar edge of M3; palatal length a (PLa), midline distance between posterior margins of upper incisors to anterior margin of mesopterygoid fossa; palatal length b (PLb), anterior edge of PM4 to anterior edge of mesopterygoid fossa; incisive foramina length (IFL), length of opening of foramina; bullar length (BuL), maximal distance from anterior to posterior edges of tympanic bulla; postpalatal length (PPL), posterior margin of inner aspect of zygomatic arch to a line perpendicular and tangent to greatest projection of occipital region; mesopterygoid fossa width (MPF), maximum width taken at the suture between palatine and pterygoid bones; first molar breath (M1B), greatest distance from lingual to buccal borders of crown; maxillary breadth (MaxB), greatest breadth of maxilla on outside of M3; occipital condyle width (OccW), width across outside margins of the occipital condyles; rostral depth (RD), depth of rostrum at the suture between premaxilla and maxilla; mandible length (MBL), from the lingual border of the incisors' alveoli to the posteriormost border of the postcondyloid process; mandible height (MH), shortest distance taken vertically from the uppermost part of the condyloid process to a plane passing from the lower edge of the symphiseal suture to the lowermost edge of the angular process; cranial depth (CD), vertical distance from ventral margin of bulla to top of cranium; cranial depth at M1 (CDM1). The measurements of the holotype were taken from Thomas (1928) and Iack-Ximenes et al (2005). In addition, we compared our specimens with photographs from…”

“…Emmons (2005),Iack-Ximenes et al (2005),Blake et al (2010),Emmons et al (2015), andMosquera et al (2016).…”