Chromosomal analysis of three Brazilian "eleutherodactyline" frogs (Anura: Terrarana), with suggestion of a new species (original) (raw)
Related papers
Hereditas, 2009
We report a cytogenetic analysis of three Pristimantis fenestratus frog populations of the Amazon region in Brazil. The specimens were sampled in Borba and Manaus, Amazonas State, and in Rio Branco, Acre State. They were analyzed using Giemsa, silver staining, C-banding and FISH with rDNA probes. The karyotypes of the three populations revealed 2n = 34 chromosomes, but they differed in the number and position of Ag-NORs and in the heterochromatin pattern as well. The NOR was located on the pairs 05 and 07 in the Rio Branco specimens, pair 10 in the Manaus specimens, and pair 1 in the Borba specimens. A small C-band was detected on the telomeric region of the pair 05 in the Borba population, while in the Manaus there was a heterochromatic block adjacent to the centromere of pair 9. An unusual intra-individual variation of chromosome number was observed in metaphases of Rio Branco specimens, comprising fundamental numbers of 33, 34 and 35. Additionally, interchromosome thread connections were detected between telomere – telomere, centromere – telomere and centromere – centromere regions, and among chromosomal heterochromatin-rich sites. The NOR sites were also involved in those connections. We hypothesize that this variation is due to chromosome missegregation during mitosis. The inter- and intraindividual variation in chromosome number suggests chromosomal instability in P. fenestratus, which has not been detected in any other anuran group. Since Borba is the type-locality of P. fenestratus, a taxonomic review of the Manaus and Rio Branco populations should be done, as indicated by the cytogenetic evidence that they could be new species of Pristimantis.
Genetics and Molecular Biology, 2009
A recent substantial rearrangement of the 882 described eleutherodactyline frog species has considerably improved the understanding of their systematics. Nevertheless, many taxonomic aspects of the South American eleutherodactyline species remain unknown and require further investigation using morphological, cytogenetic and molecular approaches. In this work, the karyotypes of the Brazilian species Ischnocnema juipoca (Atibaia and Campos do Jordão, SP), Barycholos cf. ternetzi (Uberlândia, MG, and Porto Nacional, TO), and Pristimantis crepitans (Chapada dos Guimarães and São Vicente, MT) were analyzed using Giemsa staining, Ag-NOR labeling, and C-banding techniques. All individuals had a diploid number of 22 chromosomes, but the Fundamental Numbers were different among species. The herein described low chromosome number of Pristimantis crepitans is unique within this genus, suggesting that cytogenetically this species is not closely related either to its congeneric species or to Ischnocnema. In addition, karyotype differences, mainly in the NOR position, clearly distinguished the two Barycholos populations, besides indicating the existence of a so far undescribed species in this genus. A taxonomic review could clarify the systematic position of P. crepitans and verify the hypothetic new Barycholos species.
South American Journal of Herpetology, 2009
In this study we describe the morphological variation of Ischnocnema ramagii from a population sample within the Municipality of Salvador, Bahia State, Brazil, and characterize two extremely distinct morphotypes within this taxon (striped vs. non-striped dorsum); we describe its karyotype, and compare the karyotypic structure of the distinct morphotypes recognized herein. Specimens with striped dorsa were less common (13-18%) than those with non-striped dorsa (81-86%), the latter group comprising a mix of discrete color pattern states, whose frequencies were not different among juveniles, males, and females. The PCAs on morphometric data resulted in a strong degree of superposition between striped and non-striped dorsa, for both genders. We encountered a diploid number of 30 chromosomes for both males and females, with chromosome pairs 1 to 15 being telocentric. The karyotypic comparison between specimens with striped and non-striped dorsa did not show any noticeable difference. Nevertheless the karyotype of I. ramagii from Salvador, Bahia, differed from the karyotype described for I. paulodutrai from Ilhéus, Bahia, which showed a submetacentric chromosome pair. This result supports the presence of two full "sibling" species in Bahia State, one from the south (I. paulodutrai) and another from the north (I. ramagii), validating the identity of I. paulodutrai as a full species, and refuting the recognition of Salvador samples as I. paulodutrai. The high number of telocentric chromosomes suggests a closer relationship between I. ramagii and "Eleutherodactylinae" species from Central America and the northern region of Brazil.
2014
New World direct-developing frogs (Terrarana) are among the most diverse vertebrate groups in the world. Many Terrarana species are highly variable in colouration and morphology, often rendering it difficult to delineate species. Modern molecular and bioacoustic techniques are a relatively recent tool for understanding the various taxonomic entities. This affects also Pristimantis caryophyllaceus, a complex on which little research has previously been done. We examined the variation of morphology, genetics, and colouration in specimens affiliated to P. caryophyllaceus from Panama, using different Molecular Operational Taxonomic Units (MOTUs) based on molecular phylogenetic lineages. Phylogeny, ecology, and distributional information for this species shed light on the position and species delineation of P. caryophyllaceus and its congeners in Panama. Our results demonstrate a high level of genetic diversity in P. caryophyllaceus-like populations from Panama, which in fact comprise three main lineages that are geographically separated. Specimens from eastern Panama tend to be larger, with more expanded finger disks and toe pads than specimens from western Panama. However, aside from the significant morphological differences between MOTUs, the extent of variation within each MOTU is very large. Based on our extensive and integrative analysis, we suggest treating the three MOTUs of P. caryophyllaceus populations as a single polymorphic species with very deep conspecific lineages as a result of the dynamic geological history of the Isthmus of Panama. The validity of the recently described P. educatoris is not supported by our results and we therefore synonymize it with P. caryophyllaceus.
The genus Pristimantis contains many species and species groups that are difficult to differentiate. These frogs show high intraspecific morphological variability and low morphological divergence between species, which contributes to misclassification of taxa and systematic uncertainties. Morphometric assessments coupled with the use of molecular markers are opening new avenues to resolve the taxonomy of this group, allowing for identification of informative characters. Morphometric and genetic analyses were applied to differentiate three species of Pristimantis (P. calcaratus, P. kelephas, and P. jubatus) previously confused in their identification and description. We evaluated 51 qualitative and quantitative morphological characters with sequences of two mitochondrial (mt) genes (16S and cytochrome oxidase subunit I [COI]). We used discriminant analysis to show that these species could be differentiated by two qualitative morphological characters (posterior surfaces of thighs and longitudinal stripes on the dorsum), whereas one quantitative variable (distance from tympanum to eye) differentiates only adults of the three species. Our genetic data showed highest divergence in comparisons of P. jubatus (>13%) with the other two species, whereas comparisons between P. kelephas and P. calcaratus were 2.6% and 8.3% for 16S and COI, respectively. These differentiations suggest that they are well-delimited species on the basis of morphological and mt deoxyribonucleic acid data. Nevertheless, the genetic differentiation between P. calcaratus and P. kelephas implied a recent divergence and showed the importance of using both morphometric and genetic analysis in species recognition.
Cytogenetics of two hylid frogs from Brazilian Cerrado
Genetics and Molecular Biology
Cytogenetic data can be useful for taxonomic and phylogenetic studies, as well as to provide information about chromosome evolution. Therefore, it may help design conservation priorities for some threatened species, such as anurans. Herein, we describe the karyotypes of Scinax constrictus and Ololygon centralis, native endemic species from the Brazilian Cerrado. Chromosome preparations for both species were stained with Giemsa for morphological analyses and then impregnated by the Ag-NOR method for localization of the nucleolar organizer region (NOR). Both species had 24 chromosomes, as confirmed by meiotic analyses, which showed 12 bivalents. Chromosome morphologies presented the same pattern for Scinax and Ololygon compared to species already karyotyped in both genera. The NOR was interstitially located in the long arm of pair 7 in S. constrictus, whereas in O. centralis it was found near the centromere in the long arm of pair 1, thus diverging from what is commonly found for other Ololygon species. Therefore, we provide the first description of the karyotype of O. centralis and the first report of the localization of the NOR for the karyotype of both species. Our study increases the cytogenetic knowledge in species of the genera Scinax and Ololygon, and provide support for further studies on the taxonomy, ecology, and evolution of hylid anurans.
Zoological studies
- Intrageneric karyotypic variation in Pseudopaludicola (Anura: Leiuperidae) and its taxonomic relatedness. Zoological Studies 50(6): 826-836. Herein, we report karyological data for Pseudopaludicola frogs, with the main objective to investigate the confusing taxonomic identification of these anurans. The samples analyzed included topotypes of P. falcipes and P. ameghini (currently considered a synonym of P. mystacalis) in addition to specimens of P. mystacalis and P. ternetzi and of 8 additional populations of Pseudopaludicola from several regions of Brazil. Interspecific variations in the chromosome number, location of the nucleolar organizer region (NOR), and banding patterns were observed. The karyotype of P. falcipes consisted of 2n = 22 chromosomes, whereas P. ameghini (sensu Cope 1887) and P. ternetzi had 2n = 20 and P. mystacalis had 2n = 16 chromosomes. The chromosome number 2n = 16 was also found in specimens of populations from Santa Fé do Sul, Vitória Brazil, Icém, Palestina (southeastern Brazil), Barreirinhas, Urbano Santos (northeastern Brazil), Poconé, and Santa Terezinha (west-central Brazil). Nevertheless, in some individuals from Icém and Poconé, we found 2n = 20 and 2n = 22 chromosomes, respectively. This variation in chromosome number indicates diverse taxa coexisting in sympatry. The karyotypic patterns of 2n = 20 in P. ameghini (sensu Cope 1887) and 2n = 16 in P. mystacalis are clearly indicative of 2 distinct taxonomic units. Therefore, our data corroborate the removal of P. ameghini from synonymy with P. mystacalis as previously suggested. We define the karyotype of P. falcipes as 2n = 22 and of P. ternetzi as 2n = 20 and reinforce the need for a taxonomic revision of this genus.
Chromosomal Variation in the Species of the Physalaemus henselii Group (Anura: Leiuperidae
Journal of Herpetology, 2009
In this work, we studied chromosome morphology, Ag-NOR, and C-banding patterns in the Neotropical leiuperid frogs that compose the Physalaemus henselii species group: Physalaemus fernandezae, Physalaemus henselii, and Physalaemus riograndensis. The chromosome diploid complement in all species was 2n = 22 and consisted of seven large to medium and four small chromosome pairs. Chromosome fundamental number (FN) varied, because pair 11 was metacentric in P. henselii and P. riograndensis (FN = 44) but telocentric in P. fernandezae (FN = 42). Each species presented a single pair of Ag-NORs, which are located in the secondary constriction of pair 11 in the case of P. fernandezae, in pair 8 in P. riograndensis (as in many other Physalaemus species), and in pair 5 in P. henselii, which is a unique character state among leiuperids. There were no substantial interspecific differences in C-banding pattern, and the heterochromatic bands were mainly located in the centromeric regions of all chromosomes. Noncentromeric C-bands adjacent to NORs were detected in P. riograndensis and P. fernandezae, as already reported for other species of this genus. The karyotype of P. fernandezae was quite similar to that of species in the P. signifer group and of the leiuperid Eupemphix nattereri. Neither karyotypic data nor adult and larval morphology support the P. henselii species group as currently defined.
Chromosome analysis of five Brazilian species of poison frogs (Anura: Dendrobatidae)
Journal of Genetics, 2011
Dendrobatid frogs have undergone an extensive systematic reorganization based on recent molecular findings. The present work describes karyotypes of the Brazilian species Adelphobates castaneoticus, A. quinquevittatus, Ameerega picta, A. galactonotus and Dendrobates tinctorius which were compared to each other and with previously described related species. All karyotypes consisted of 2n = 18 chromosomes, except for A. picta which had 2n = 24. The karyotypes of the Adelphobates and D. tinctorius species were highly similar to each other and to the other 2n = 18 previously studied species, revealing conserved karyotypic characteristics in both genera. In recent phylogenetic studies, all Adelphobates species were grouped in a clade separated from the Dendrobates species. Thus, we hypothesized that their common karyotypic traits may have a distinct origin by chromosome rearrangements and mutations. In A. picta, with 2n = 24, chromosome features of pairs from 1 to 8 are shared with other previously karyotyped species within this genus. Hence, the A. picta data reinforced that the C-banding pattern and the NOR location are species-specific traits in the genus Ameerega. Moreover, the Ameerega monophyletism proposed by previous phylogenetic studies indicates that the karyotypic differences among species in this genus result from a long divergence time.
Ecology and Evolution, 2021
Archolaemus, one of the five genera of Neotropical freshwater fish of the family Sternopygidae (Gymnotiformes), was long considered a monotypic genus represented by Archolaemus blax. Currently, it consists of six species, most of them occurring in the Amazon region. There are no cytogenetic data for species of this genus. In the present study, we used classical cytogenetics (conventional staining and C‐banding) and molecular cytogenetics (probes of telomeric sequences and multigenic families 18S rDNA, 5S rDNA, and U2 snDNA) to study the karyotype of Archolaemus janeae from Xingu and Tapajós rivers in the state of Pará (Brazil). The results showed that the two populations have identical karyotypes with 46 chromosomes: four submetacentric and 42 acrocentric (2n = 46; 4m/sm + 42a). Constitutive heterochromatin occurs in the centromeric region of all chromosomes, in addition to small bands in the interstitial and distal regions of some pairs. The 18S rDNA occurs in the distal region of the short arm of pair 2; the 5S rDNA occurs in five chromosome pairs; and the U2 snDNA sequence occurs in chromosome pairs 3, 6, and 13. No interstitial telomeric sequence was observed. These results show karyotypic similarity between the studied populations suggesting the existence of a single species and are of great importance as a reference for future cytotaxonomic studies of the genus.