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Giemsa-stained (A), NOR-bearing chromosome pair in the inset (B) and C-banded (C) of Brachycephalus ephippium karyotype. Bar = 4 µm.
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... closely related species, the dispersion of the NOR throughout in the genome indicates that chromosomal rearrangements involving the segment that carries the NOR occur frequently across an evolutionary time-span. The C-banding technique showed the association of heterochromatin with the NOR ( figs 1C and 2). All of the chromosomes had a large amount of centromeric heterochromatin that, in almost all chromosomes, was detected as an interstitial band adjacent to the cetromere. ...
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... The other karyotyped species of genera Ischnocnema and Brachycephalus, both within family Brachycephalidae, were substantially diverse from those described herein. Those other species, such as I. guentheri, I. parva and B. ephippium, have the same chromosome number as I. juipoca (2n = 22), but no telocentric chromosomes (Siqueira et al., 2004; Ananias et al., 2006), whereas I. holti and I. lactea present a diploid number of 20 chromosomes (De ). In addition , in B. ephippium the NOR was located interstitially on the metacentric pair 8, while in I. juipoca it was on the telocentric pair 11. ...
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.
... Among the many new clades (and proposed taxonomic rearrangements), both analyses revealed Brachycephalus to be nested within direct-developing leptodactylids. The position of Brachycephalus among anurans has always been controversial (Noble 1931;Griffiths 1963;Izecksohn 1971;McDiarmid 1971;Ananias et al. 2006). However, the hypothesis that this genus may be closely related to the small leptodactylids of the genus Euparkerella first was suggested by Izecksohn (1971;1988) and later supported by Pombal et al. (1998) and Giaretta and Sawaya (1998); recently, it was corroborated by Darst and Cannatella (2004) and Frost et al. (2006). ...
We surveyed the morphology of the auditory region of members of the anuran genus Brachycephalus. The sample included seven of the eleven known species; in addition, Brachycephalus ephippium and B. vertebralis were each represented by several specimens from different localities. All species lack a tympanum, tympanic annulus, stapes, and Eustachian tube. However, the operculum and the m. opercularis remain. The large operculum bears a robust process for the m. opercularis and covers most of the fenestra ovalis. The auditory apparatus of Brachycephalus is distinguished by the large size and the orientation of the fenestra ovalis, which faces posterior, rather than lateral. The morphology of these structures is compared to those of other minute brachycephalid frogs considered to be close relatives of Brachycephalus, and the importance of these characters as evidence of the monophyly of the genus is discussed. We also discuss the importance of other morphological features cited to support close relationships among small-sized brachycephalids, and consider the role of miniaturization in generating convergent pattern of loss of morphological features.
... Among the many new clades (and proposed taxonomic rearrangements), both analyses revealed Brachycephalus to be nested within direct-developing leptodactylids. The position of Brachycephalus among anurans has always been controversial (Noble 1931;Griffiths 1963;Izecksohn 1971;McDiarmid 1971;Ananias et al. 2006). However, the hypothesis that this genus may be closely related to the small leptodactylids of the genus Euparkerella first was suggested by Izecksohn (1971;1988) and later supported by Pombal et al. (1998) and Giaretta and Sawaya (1998); recently, it was corroborated by Darst and Cannatella (2004) and Frost et al. (2006). ...
Dissertação (mestrado)—Universidade de Brasília, Departamento de Ciências Fisiológicas, Brasília, 2007. Texto parcialmente liberado pelo autor. Conteúdo: Sumário, Resumo, Abstract, Capítulo 1 parte 1, Capítulo 1 parte 2, Referências Bibliográficas. O surgimento de novidades morfológicas e o aumento de tamanho e de complexidade são eventos evolutivos raros. Por outro lado, a redução de tamanho e a perda de estruturas e de complexidade talvez sejam os eventos mais comuns no processo evolutivo. No gênero Brachycephalus, encontramos um mosaico dessas duas tendências: simplificação e novidades morfológicas. Na diagnose de todas as espécies deste gênero, menciona-se a presença e ausência de ossificações dérmicas. No entanto, nem todos os trabalhos de descrição usam métodos apropriados para a descrição de dados osteológicos. As placas ósseas associadas às vértebras e ao crânio de Brachycephalus ephippium foram classificadas como osteoderme. Contudo, o desenvolvimento ontogenético dessas estruturas não foi estudado. O recente trabalho de Frost et al. (2006), propões várias mudanças na taxonomia e sistemática na maioria das grandes famílias de anfíbios. De acordo com este trabalho, não existem caracteres morfológicos que suportem a monofiletismo do gênero Brachycephalus. Adicionalmente, este trabalho sugere a proximidade filogenética entre os gêneros Brachycephalus, Euparkerella e Adelophryne, baseada em padrões supostamente homólogos de redução e perda de falanges. Entretanto, essas hipóteses foram baseadas apenas em Brachycephalus ephippium, que por décadas foi a única espécie do gênero. Consequentemente, muito da diversidade osteológica do gênero Brachycephalus não foi considera nestes estudos prévios. Os objetivos desta dissertação foram: 1) a descrição da ontogenia das placas ósseas associadas ao crânio e vértebras de Brachycephalus ephippium; 2) a descrição da diversidade morfológica das placas ósseas entre espécies do gênero Brachycephalus e 3) avaliar a importância da osteologia do aparato auditivo de Brachycephalus para o monofiletismo do gênero. Adicionalmente, reavaliamos os dados da literatura sobre redução de falanges no grupo e as conseqüências taxonômicas envolvidas. Exemplares de Brachycephalus ephippium foram coletados em Atibaia, Cotia, Mogi das Cruzes e Itamonte. Incluímos também espécimes de B. brunneus, B. hermogenesi, B. nodoterga, B. pernix, B. cf. vertebralis, B. vertebralis, e duas espécies não descritas aqui referidas como Brachycephalus sp1 (de Nova Friburgo e Petrópolis) e B. sp2 (Faz. Capricórnio, Ubatuba). Os espécimes foram mortos por injeção de cloridrato de bupivicaína 0,2% e então submetidos às seguintes preparações: maceração e microscopia eletrônica de varredura; diafanização e coloração com alizarina e azul de alcian e microscopia de luz. Nossos resultados indicam que as placas ósseas de B. ephippium são estruturas independentes aqui classificadas como ossos ordinários e não como osteoderme. Existem três tipos de placas ósseas: 1) a placa parótica, localizada na porção postero-lateral do crânio; 2) as placas espinhais, fusionadas aos processos espinhais de todas as vértebras e 3) as placas para-vertebrais, associadas aos processos transversos das vértebras IV e V. O tipo de ossificação das placas ósseas é intermembranoso (também conhecido como ossificação dérmica). Entretanto, a formação das placas não ocorre no tegumento, como mencionado em trabalhos anteriores. Adicionalmente, encontramos evidências histológicas de que o pericôndrio das vértebras em crescimento contribui com células que formam a membrana perióstea das placas paravertebrais e espinhais. A possibilidade de participação de células da derme na formação do periósteo das placas ósseas não foi descartada. No entanto, estas estruturas não cabem no termo osteoderme, que até o momento, está definido de forma confusa, agrupando uma série de estruturas possivelmente não homólogas. Não existem precedentes na literatura de registro de estruturas semelhantes às placas paróticas. As placas associadas às vértebras, entretanto, estruturas possivelmente análogas são encontradas em outros gêneros como Dendrobates, Ceratophrys e Lepdobatrachus. Todavia, serão necessários estudos osteológicos. ____________________________________________________________________________ ABSTRACT The rising of morphological novelties, growth of body size and structural complexity are uncommon evolutionary events. On the order hand, the miniaturization of body size and morphological simplification may be the most usual tendencies in the evolutionary process. Incredibly, both morphological novelties and morphological simplification could be observed in species of Brachycephalus. In the genus Brachycephalus, in all species diagnosis, the presence and absence of dermal ossifications is mentioned. Nevertheless, not all descriptions use appropriate methods for osteological studies. The plates associated with vertebrae and skull of B. ephippium were, previously, identified as osteoderm. Though, there are not any studies on ontogens and development of these structures in Brachycephalus. The recent work of Frost et al. (2006) proposes taxonomic and systematic changes in most amphibians family clades. According to this article, there are no currently known morphological characters that support the monophyly of the genus Brachycephalus. In addition, Frost et al (2006) corroborate the hypothesis of a close relationship among geni Brachycephalus, Euparkerella and Adellophryne, based on digital reduction and loss patterns. Though, these considerations were made using only B. ephippium, and thus, too much osteological diversity among Brachycephalus species were not evaluated in previous works. The goals of this dissertation are:1) ontogenetic description of the bony plates present in vertebrae and skull of B. ephippium; 2) description of morphological variations in this plates in species of the genus Brachycephalus; 3) evaluate the importance of the auditory region osteology and falangeal formulae to the monophyly of the genus Brachycephalus. We also reevaluate the available information on digital reduction and its importance to the systematics of the taxa involved. Units of B. ephippium were collected in Atibaia, Cotia, Mogi das Cruzes, Teresópolis and Itamonte. In addition, we included units of B. brunneus, B. hermogenesi, B. nodoterga, B. pernix, B. cf. vertebralis, B. vertebralis, and two undescribed species: Brachycephalus sp1 (from Nova Friburgo and Petrópolis, RJ Brazil) and Brachycephalus sp2 (from Faz. Capricórnio, in Ubatuba, SP Brazil). The specimens were killed with bupivicaine chloridrate (0.2%) and submitted at scanning electronic microscopy. Other specimens were fixed in formalin solution (10%), cleared and double stained with alizarin red and alcian blue Juvenile xi specimens of B. ephippium were submitted to histological techniques for ontogenetic description of the bony plates. We report that the bony plates are new, independent, and ordinary bone structures, that arise in early development stages. There are three types of bony plates, where named: 1) parotic plates, found in the postero-lateral portion of skull; 2) spinal plates, fused with spinal processes of all vertebrae and 3) paravertebral plates, associated with transverse processes of IV and V vertebrae.The bony plates type of ossification is intermembranous (named also as dermal ossification). However, its rising does not take place in integument, like proposed previously in literature. In addition, we found histological evidences that the perichondrial membrane of the growing vertebrae, releases cells to form a periosteal membrane of the paravertebral and spinal plates. The possibility of participation of dermal cells in the formation of precursor tissue of bony plates was not discarded. However, we decided that these structures are not osteoderms. This term is confused, and possibly enclose many non homologous structures. That is the first time that a structure like the parotic plate is being reported in literature. However, the spinal and paravertebral plates may have analogous structures in other genus, as Ceratophrys, Lepidobatrachus and Dendrobates. Nevertheless, a complementary comparative osteological studies will be necessary to analyzed the semblance among the bony plates in other geni. The morphological variations of the bony plates in the genus Brachycephalus suggest that there are monophyletic groups in the genus, that may be recognized by following patterns:1- absence of bony plates (occurring in B. brunneus, B. didactylus, B. ferruginus, B. hermogenesi, B. izecksohni, B. pernix and B. pombali); 2- presence of parotical plates and spinal and paravertebral plates of variable size and degree of ossification and ornamentation (occurring in B. ephippium, B. nodoterga, B. vertebralis, B. sp1 and B. sp2). Nevertheless, the monophyly of these groups remind to be tested in a phylogenetic analysis, using data from different sources. The auditory apparatus of most anurans is composed of a tympanic membrane, connected to the stapes. It is connected to the operculum, which conduces the sound vibrations to the inner ear. In Brachycephalus species the tympanic membrane and the stapes are absent. In addition, we discovered a new set of characters that may corroborate the monophyly of the genus: 1) the posterior orientation of the fenestra ovalis; 2) the enlarged operculum that nearly xii fills the fenestra ovalis; 3) bears a large process for the attachment of the m. opercularis and 4) absence of one phalange in digit V. Analyzing the osteology of species that were recently included in Brachycephalidae, and other miniaturized species among other groups, we conclude that these characters are unique to Brachycephalus genus, and support its monophyly. Other important conclusion is that the digital morphology does not corroborate a close relationship between Brachycephalus and Euparkerella or either Adeloprhyne, as suggested by Frost et al. (2006). The position of Brachycephalus in the Brachycephalidae remains to be analyzed in further investigations.
Mountains of the Brazilian Atlantic Forest can act as islands of cold and wet climate, leading to the isolation and speciation of species with low dispersal capacity, such as the toadlet species of the genus Brachycephalus. This genus is composed primarily by diurnal species, with miniaturized body sizes (<2.5 cm), inhabiting microhabitats in the leaf litter of montane forests. Still, little is known about the geographical distribution, altitudinal range, and ecological limits of most Brachycephalus species. In this study, we review the available data on the geographical and altitudinal distribution of Brachycephalus based on occurrence records compiled from literature and museums, both for the genus as a whole and separately for the three recently proposed groups of species (ephippium, didactylus, and pernix). The final ensemble dataset comprised 333 records, 120 localities, 28 described species, and six undescribed ones. Species were recorded in six relief units, the richest of which being the Serra do Mar, with 30 species. When the Serra do Mar is subdivided into three subunits, Northern, Central and Southern Serra do Mar, the number of species increase from north to the south, with records of six, nine, and 16 species, respectively. We were able to estimate the extent of occurrence of nearly half of the described species, and the resulting estimates indicate that many of them show remarkably small ranges, some of which less than 50 ha. Brachycephalus species are present from sea level to roughly 1,900 m a.s.l., with the highest richness being found between 751 and 1,000 m a.s.l. (21 spp.). The species with the broadest altitudinal range were B. didactylus (1,075 m) and Brachycephalus sp. 1 (1,035 m), both in the didactylus group, and B. ephippium (1,050 m), of the ephippium group. The broadest altitudinal amplitude for species of the pernix group was recorded for B. brunneus (535 m). The lowest altitudinal records for the pernix group were at
We surveyed the morphology of the auditory region of members of the anuran genus Brachycephalus. The sample included seven of the eleven known species; in addition, Brachycephalus ephippium and B. vertebralis were each repre-sented by several specimens from different localities. All species lack a tympanum, tympanic annulus, stapes, and Eus-tachian tube. However, the operculum and the m. opercularis remain. The large operculum bears a robust process for the m. opercularis and covers most of the fenestra ovalis. The auditory apparatus of Brachycephalus is distinguished by the large size and the orientation of the fenestra ovalis, which faces posterior, rather than lateral. The morphology of these structures is compared to those of other minute brachycephalid frogs considered to be close relatives of Brachycephalus, and the importance of these characters as evidence of the monophyly of the genus is discussed. We also discuss the importance of other morphological features cited to support close relationships among small-sized brachycephalids, and consider the role of miniaturization in generating convergent pattern of loss of morphological features.
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