Karyotypic divergence reveals that diversity in the Oecomys paricola complex (Rodentia, Sigmodontinae) from eastern Amazonia is higher than previously thought.

The genus Oecomys (Rodentia, Sigmodontinae) is distributed from southern Central America to southeastern Brazil in South America. It currently comprises 18 species, but multidisciplinary approaches such as karyotypic, morphological and molecular studies have shown that there is a greater diversity within some lineages than others. In particular, it has been proposed that O. paricola constitutes a species complex with three evolutionary units, which have been called the northern, eastern and western clades. Aiming to clarify the taxonomic status of O. paricola and determine the relevant chromosomal rearrangements, we investigated the karyotypes of samples from eastern Amazonia by chromosomal banding and FISH with Hylaeamys megacephalus (HME) whole-chromosome probes. We detected three cytotypes for O. paricola: A (OPA-A; 2n = 72, FN = 75), B (OPA-B; 2n = 70, FN = 75) and C (OPA-C; 2n = 70, FN = 72). Comparative chromosome painting showed that fusions/fissions, translocations and pericentric inversions or centromeric repositioning were responsible for the karyotypic divergence. We also detected exclusive chromosomal signatures that can be used as phylogenetic markers. Our analysis of karyotypic and distribution information indicates that OPA-A, OPA-B and OPA-C are three distinct species that belong to the eastern clade, with sympatry occurring between two of them, and that the "paricola group" is more diverse than was previously thought

Chromosomal phylogeny and comparative chromosome painting among Neacomys species (Rodentia, Sigmodontinae) from eastern Amazonia

Abstract: 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

Microscopia digital das pontas diamantadas para acabamento dos pinos intra radiculares pré-fabricados estéticos

Objetivo: O objetivo deste trabalho foi a avaliação por meio de imagens de microscopia digital utilizando diferentes tipos de acabamento. Métodos: Neste trabalho foram utilizados pinos de fibra de vidro de tamanho n.1, foram realizados acabamento com a seguintes pontas diamantadas: 3195, 3195F e 3195FF, formando um total de 4 grupos sendo grupo controle e os outros 3 pertencente a cada ponta diamantada respectivamente. Posteriormente foi analisado em Microscópio se houve alguma alteração em sua estrutura superficial. Resultados: No primeiro grupo foram realizados acabamentos com a ponta diamantada 3195F, apresentando então menor preservação da estrutura superficial do pino. No segundo grupo foram realizados acabamentos com a ponta diamantada 3195FF, apresentando assim variação quanto a preservação da estrutura superficial do pino. No terceiro grupo foram realizados acabamentos com a ponta diamantada 3195, obtendo assim melhor preservação da estrutura superficial do pino. Já o quarto grupo foi utilizado como grupo controle. Conclusão: A utilização da ponta diamantada 3195 apresentou maior padrão de homogeneidade e preservação da estrutura do material

Comparative genomic mapping reveals mechanisms of chromosome diversification in Rhipidomys species (Rodentia, Thomasomyini) and syntenic relationship between species of Sigmodontinae

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 results show that the genomic diversification between the karyotypes of the two species resulted from translocations, centromeric repositioning and pericentric inversions. The chromosomal evolution in Rhipidomys was associated with karyotypical orthoselection. The HME probes revealed that seven syntenic probably ancestral blocks for Sigmodontinae are present in Rhipidomys. An additional syntenic block described here is suggested as part of the subfamily ancestral karyotype. We also define five synapomorphies that can be used as chromosomal signatures for Rhipidomys

Catálogo Taxonômico da Fauna do Brasil: setting the baseline knowledge on the animal diversity in Brazil

The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the Catálogo Taxonômico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others

Marmosops (Sciophanes) pinheiroi

Marmosops (Sciophanes) pinheiroi (Pine, 1981) Marmosa parvidens pinheiroi Pine, 1981: 61. Marmosops pinheiroi: Voss et al. 2001: 49 (part); name combination. M [armosops]. pirenhoi Flores, 2004: 133 (part); incorrect spelling of Marmosops pinheiroi (Pine, 1981). [Marmosops Schiophanes] pinheiroi: Díaz-Nieto et al. 2016: 928; first use of the current name combination. Holotype. USNM 461459 (original numbers T-391 and L5049) consists of the skin and skull of an adult female collected on 08 May, 1969, by personnel of the Institute Evandro Chagas. Type locality. Serra do Navio (0º59’N, 52º03’W), left bank of the Rio Amapari, state of Amapá, Brazil. Geographic distribution. It occurs in the Guiana Shield and east of the Negro River, from southeastern Ven-ezuela to the Amazon River, through Guyana, Suriname, French Guiana and the states of Amapá, Roraima and Pará in Brazil (Figure 5). Amended diagnosis. Dorsal coloration grayish-brown; tail length (LT: 120–167 mm) much longer than head and body length (HBL: 75–115 mm); ventral coloration ranging from white to cream, with wide lateral bands of gray-based and white-tipped hairs, which usually join on the throat and do not extend to the inner surface of the hind limbs; lacrimal foramina exposed in lateral view; supraoccipital with slightly convex shape in dorsal view; upper third molar (M3) with anterior and posterior portions of the stylar shelf projected labially in the same proportion (in occlusal view); upper molars with preprotocrista and anterolabial cingulum seperated, not forming a continuous shelf along the anterior margin of the tooth crown; metaconule of the upper molars slightly developed; and talonid of the lower fourth molar (m4) usually bicuspid. Morphological description. Marmosops pinheiroi (s.s) has a head and body size of 75–115 mm and longer tail (LT: 120–167 mm; Tables 4 and 5); dorsal hairs 6–8 mm long; dorsal fur smooth, grayish-brown, being slightly lighter laterally; rostrum lighter than the top of the head, presenting light brown coloration, with some pale red and gray hairs; mask around the eyes blackish, with conspicuous posterior portion; cheeks with a greater amount of white hairs, but gray-based and white-tipped hairs also present; hands covered dorsally by whitish hairs; tail bicolor, generally grayish brown dorsally (73.8%, n=42); tail scales arranged in a spiral, each with three hairs inserted in the posterior margin; the central hair of the triplet clearly thicker and more pigmented than the lateral ones; venter varying from cream to white, with wide lateral bands of gray-based and white-tipped hairs (except in MPEG 40017, 40027, 40406, 40407, which have slightly narrower lateral bands), usually joining on the throat (74%, n=42) and not extending to the inner surface of the hind limbs (64.3%, n=42); hands with lateral spoon shaped carpal tubercle in adult males. Craniodentally, Marmosops pinheiroi (s.s.) exhibits a zygomatic process of the squamosal widely overlapped dorsally by the jugal; lacrimal foramina exposed in lateral view (except in MPEG 39972 and 40025, in which foramina are not exposed); supraorbital margin slightly rounded with non-prominent crest; long nasal bones (ex-tending slightly behind the lacrimal) and wider posteriorly than anteriorly (except in MPEG 2277; MNRJ 70256, 70359, 70362 70730, 70798, whose nasal bones are similarly wide along all extension); supraoccipital with slightly convex shape in dorsal view; paraoccipital process generally long and narrow (77.7%, n=36); tympanic process of alisphenoid with ventral surface usually oval (75.7% n=37); cochlear fenestrae exposed in ventral view (except in MNRJ 70256, 70730); palatine fenestrae absent, but diminutive perforations in the palatine and/or maxillary bones may be present (MPEG 40002, 40005, 40013, 40017, 40406; MNRJ 70256); upper canines (C1) with anterior and posterior accessory cusps in males and females; upper third molar (M3) with anterior and posterior portions of the stylar shelf projected labially in the same proportion; upper molars with preprotocrista and anterolabial cingulum separated, not forming a continuous shelf along the anterior margin of the tooth crown; metaconule of the upper molars; Figures 7B and C) undeveloped; lower canine (c1) premolariform, with posterior accessory cusp, subequal (63%, n=35) or slightly higher (37%, n=35) to the first lower premolar (p1); paraconid of the second lower molar (m2) higher than the entoconid of the lower first molar (m1); and talonid of the lower fourth molar (m4) usually bicuspid (61%, n=38). Geographic variation. We did not observe any geographic variation among samples of M. pinheiroi examined in this report. Comparisons with M. parvidens and other species of the “Parvidens” group (Table 6). Comparisons between M. pinheiroi (s.s.) and M. marina are provided above. Externally, M. pinheiroi (s.s.) is distinguished from M. parvidens and M. woodalli by exhibiting grayish-brown dorsal color (Figure 4C), versus slightly reddish brown in M. parvidens (Figure 4B) and usually dark brown in M. woodalli (Figure 4D); ventral coloration varying from cream to white (Figure 4C), versus cream in M. parvidens (Figure 4B) and white in M. woodalli (Figures 4D); lateral bands of gray-based hairs wide on the venter, usually joining on the throat and not extending to the inner surface of the hind limbs (Figure 4C), versus usually absent in M. parvidens, whose venter is covered with a continuous band of cream colored hairs extending along the inner surface of the anterior and posterior limbs (Figure 4B), and narrow and irregularly arranged, joining or not on the throat and/or mid-chest in M. woodalli (Figure 4D). Is also differs from M. parvidens by exhibiting conspicuous blackish facial mask around the eyes that extends posteriorly (versus usually inconspicuous; Table 6). Finally, M. pinheiroi (s.s) has, on average, longer feet (Tables 4 and 5) and shorter dorsal fur than M. woodalli (6.9 mm in the former versus 7.6 mm in the latter species). Craniodentally, M. pinheiroi (s.s.) differs from M. parvidens and M. woodalli by exhibiting lacrimal foramina exposed (versus variably exposed) in lateral view; tympanic process of the alisphenoid with ventral surface usually oval, versus usually globose in M. parvidens and variable in M. woodalli; and talonid of the lower fourth molar (m4) usually bicuspid (versus usually tricuspid). It also differs from M. parvidens by exhibiting preprotocrista and anterolabial cingulum separated, not forming a continuous shelf on the anterior margin of crown of the upper molars (versus attached, forming a continuous shelf on the anterior margin of crown of the upper molars; Figures 7B and C); and small accessory cusp between the metaconid and the entoconid of lower molars absent (Figure 8 A-B). Marmosops pinheiroi (s.s.) can also be discriminated from Marmosops woodalli by exhibiting a slightly convex supraoccipital (versus rounded and markedly convex; Figures 9 A-B); anterior and posterior stylar portions of the M3 projected labially in the same proportion (versus posterior portion more projected labially than anterior portion; Figures 6 A-B). Habitats and sympatry. Marmosops pinheiroi (s.s.) extends along Humid Forests of Uatumã-Trombetas and Savannas of Guiana ecoregions (sensu Olson et al. 2001). The species has been recorded in sympatry with M. parvidens in Floresta Estadual de Faro, on the left bank of the Nhamundá River, state of Pará, Brazil; in Floresta Estadual de Trombetas, Óbidos, Pará, Brazil; in Oriximiná, Pará, Brazil (Figure 5); in Paracou, French Guiana (Voss et al. 2001; Voss et al. 2013; Díaz-Nieto & Voss 2016); and in Demerara-Mahaica, French Guiana (Voss et al. 2013; Díaz-Nieto & Voss 2016). a Cream in 54.7% and white in 45.3% (n=42). b Exposed in 55% and not exposed in 45% (n=11). c Exposed in 59% and not exposed in 41% (n = 70). d Diminutive perforations are present in the palatine and/or maxillary bones of 45% of examined specimens (n=70). e Attached, forming a very narrow shelf along the anterior margin of molar crown in 8.6% of the examined specimens (n=70). Natural history data. Mammary formula 4–1–4 = 9. Lactating females were recorded in March and April in Parque Nacional Viruá, state of Roraima, Brazil. Specimens examined (n=69). BRAZIL - Amapá: Macapá, rigth bank of Rio Amapari, 0°2’N, 51°4’W, 1 M (MPEG 2277); Serra do Navio, Rio Amapari, 0º54’3”N, 52º0’14”W, 1 M, 1 F (MPEG 15255, 15256); Serra do Navio, Rio Amapari, 0°59’N, 52°03’W, 1 F (USNM 461459, photograph of the holotype). Pará: Floresta Estadual Faro (Flota Faro), left bank of Rio Nhamundá, 1°16’44”S, 58°2’24”W, 1 F (MPEG 39972); Parque Estadual de Monte Alegre, Monte Alegre, 2°3’6”S, 54°10’58”W, 1 M (MPEG 38171); Óbidos, Flota Trombetas, 0°58’0”S, 55°30’60”W, 19 M, 6 F, 2? (MPEG 40002, 40005, 40012, 40013, 40016-40019, 40023-40027, 40030, 40032, 40033, 40037, 40402, 40405-40409, 40410-40412; MPEG: CN063); Oriximiná, 1°45’S, 55°51’W, 1 M, 1 F (MPEG 39805, 39806). Roraima: Caracaraí, Parque Nacional Viruá, 01º15’N, 61º9’W, 23 M, 10 F, 2? (MNRJ 70256, 70359, 70362, 70389, 70396, 70397, 70410, 70412, 70421, 70422, 70487, 70730, 70738, 70745, 70746, 70753, 70754, 70757, 70760, 70762, 70763, 70765, 70772, 70793-70795, 70798, 70802, 70819, 70833, 70856, 70923, 70950, 70953).Published as part of Ferreira, Claudilívia, Oliveira, Ana Cristina Mendes De, Lima-Silva, Luan Gabriel & Rossi, Rogério Vieira, 2020, Taxonomic review of the slender mouse opossums of the " Parvidens " group from Brazil (Didelphimorphia: Didelphidae: Marmosops), with description of a new species, pp. 201-233 in Zootaxa 4890 (2) on pages 222-225, DOI: 10.11646/zootaxa.4890.2.3, http://zenodo.org/record/430182

Chromosomal phylogeny and comparative chromosome painting among Neacomys species (Rodentia, Sigmodontinae) from eastern Amazonia

Abstract: 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