RESUMO
Many actinopterygian fish groups, including fossil and extant polypteriforms and lepisosteiforms, fossil halecomorphs, and some basal teleosts, have stout bony scales covered by layers of ganoin-an enamel layer ornamented with minute tubercles. Ganoid scales preserve well as disarticulated remains and notably constitute most of the fossil record for polypteriform in both South America and Africa. Based on two variables (tubercle size and distance between tubercles), some authors reported that the ganoin tubercle ornamentation in these scales is constant within a species and differs between species and allows distinguishing species or at least groups of species. However, despite its promising potential for assessing polypteriform paleodiversity, this tool has remained unused, probably because the variables are not well defined, and intraspecific variation does not seem to have been considered. To address this gap, we aimed to test the intraspecific and intra-individual variation in the ornamentation of ganoid scales in the type species Polypterus bichir. We propose three different parameters to describe the tubercle ornamentation: the distance between contiguous tubercles centers, their density, and their relative spatial organization. With these parameters, we investigate the variation in ganoin ornamentation among four specimens and across different regions of the body. Our results show that the distribution of the tubercles is highly variable within a same species, regardless of the body region, and sometimes even between different sectors of a same scale. Moreover, the variation observed in P. bichir overlaps with the distribution described in the literature for several extant and fossil species. Thus far, the ornamentation of ganoid scales is not a reliable diagnostical feature for polypterids.
Assuntos
Escamas de Animais , Animais , Escamas de Animais/anatomia & histologia , Peixes/anatomia & histologia , Peixes/classificação , Especificidade da EspécieRESUMO
The skin of the foot provides the interface between the bird and the substrate. The foot morphology involves the bone shape and the integument that is in contact with the substrate. The podotheca is a layer of keratinized epidermis forming scales that extends from the tarsometatarsus to the toe extremities. It varies in size, shape, amount of overlap and interacts with the degree of fusion of the toes (syndactyly). A study of toe shape and the podotheca provides insights on the adaptations of perching birds. Our analysis is based on micro-CT scans and scanning electron microscopy images of 21 species from 17 families, and includes examples with different orientations of the toes: zygodactyl (toes II and III forward), anisodactyl (toes II, III, and IV forward), and heterodactyl (toes III and IV forward). We show that in these three groups, the skin forms part of a perching adaptation that involves syndactyly to different degrees. However, syndactyly does not occur in Psittacidae that use their toes also for food manipulation. The syndactyly increases the sole surface and may reinforce adherence with the substrate. Scale shape and toe orientation are involved in functional adaptations to perch. Thus, both bone and skin features combine to form a pincer-like foot.
Assuntos
Adaptação Fisiológica , Aves/anatomia & histologia , Aves/fisiologia , Pé/anatomia & histologia , Pele/anatomia & histologia , Escamas de Animais/anatomia & histologia , Animais , Filogenia , Sindactilia , Dedos do Pé/anatomia & histologiaRESUMO
This study describes Characidium nambiquara, a new species from the upper rio Guaporé, rio Madeira basin, Brazil. The new species differs from most congeners by the presence of isthmus and area between the contralateral pectoral-fin bases completely naked. From congeners with some degree of scaleless ventral surface of the body C. nambiquara differs by having 10 circumpeduncular scales. The new species is also distinguished from congeners by the spotted colour pattern on body of the large-sized specimens and by having black dashes on all fins and conspicuous midlateral longitudinal dark stripe or conspicuous vertical bars absent. Characidium nambiquara further differs from most congeners by the presence of 34-36 pored scales on the lateral line, 3 horizontal scale rows above the lateral line and 3 horizontal scale rows from the lateral line to the midventral scale series. Remarks on intraspecific colour variation within the genus, not related to sexual dimorphism, are also provided.
Assuntos
Caraciformes/anatomia & histologia , Caraciformes/classificação , Nadadeiras de Animais/anatomia & histologia , Escamas de Animais/anatomia & histologia , Animais , Brasil , Pigmentação , Rios , Especificidade da EspécieRESUMO
Bryconops cyrtogaster, a poorly known species endemic from the Oyapock River at the border between French Guyana and Brazil, is redescribed herein based on examination of available type material, as well as newly collected material. Additionally, a new rheophilic species from the rio Jari rapids, lower Amazon basin, Brazil, is described. The two species belong to the subgenus Creatochanes and are unique among the congeneres for possessing a posteriorly positioned humeral blotch at the level of the sixth and seventh lateral line scales. They differ from each other by meristic and morphometric characters. The list of endemic species in the rio Jari basin is revised.
Assuntos
Caraciformes/classificação , Escamas de Animais/anatomia & histologia , Animais , Brasil , Caraciformes/anatomia & histologia , Rios , Especificidade da EspécieRESUMO
The quest for new light-weight materials with superior mechanical properties is a goal of materials scientists and engineers worldwide. A promising route in this pursuit is drawing inspiration from nature to design and develop materials with enhanced properties. By emulating the graded mineral content and hierarchical structure of fish scales of the Arapaima gigas from the nano to macro scales, we were able to develop bioinspired laminated composites with improved impact resistance. Activated by the addition of nano-particles of Al2O3 and nano-layers of TiN to a thermoplastic fiber substrate, new energy dissipation mechanisms operating at the nanoscale enhanced the energy absorption and stiffness of the bioinspired material. Remarkably, the newly developed materials are easily transferred to the industry with minimum associated manufacturing costs.
Assuntos
Escamas de Animais/anatomia & histologia , Peixes/anatomia & histologia , Óxido de Alumínio/química , Animais , Materiais Biomiméticos , Nanotecnologia , Titânio/químicaRESUMO
We describe the morphology of alar androconia and the female abdominal scent gland of Heliconius erato phyllis, Heliconius ethilla narcaea, and Heliconius besckei. Androconial scales of Heliconius, which are arranged in overlapping wing bands, release pheromones during courtship, probably through vibratory movements of male wings over the female to induce her to mate. An antiaphrodisiac is produced by glands located in the valves of the male and is transferred during copulation to the yellow dorsal abdominal sac present in the virgin female, causing this sac to emit a scent that reduces the attractiveness of the female for courtship with other males. Stereomicroscopy, SEM, and TEM analyses were conducted to describe the morphology of the internal and external scales and the external abdominal scent sac. The findings revealed different sizes of external androconial scales and an internal group of porous structural vesicles that are probably related to the preservation of internal space, reception and storage of secretions, and elimination of volatiles when the male is actively involved in courtship. Translucent projections on the female abdominal scent sac create open reservoirs for the reception, storage, and emission of antiaphrodisiac volatiles along with stink clubs. Male valve denticles vary in form and probably attach securely to the female sac during mating, thus ensuring secretion transfer. These features are discussed in the context of a comparative analysis.
Assuntos
Abdome/anatomia & histologia , Borboletas/anatomia & histologia , Borboletas/metabolismo , Feromônios/metabolismo , Glândulas Odoríferas/anatomia & histologia , Escamas de Animais/anatomia & histologia , Animais , Borboletas/ultraestrutura , Feminino , Masculino , Análise de Componente Principal , Glândulas Odoríferas/ultraestrutura , Diferenciação Sexual , Asas de Animais/anatomia & histologia , Asas de Animais/ultraestruturaRESUMO
Piaractus orinoquensis, a new species of serrasalmid fish, is described from the Orinoco River basin. The new species differs from congeners by having a slenderer body, relatively smaller head and snout, more compressed mid-body, fewer scales above and below the lateral line and diagnostic molecular characters in the coI mitochondrial gene region. We also provide a re-description of Piaractus brachypomus, restricting its geographic distribution to the Amazon River basin. Both species are economically important in their respective basins and need to be independently managed as distinct species.
Assuntos
Caraciformes/classificação , DNA Mitocondrial/química , Complexo IV da Cadeia de Transporte de Elétrons/genética , Nadadeiras de Animais/anatomia & histologia , Escamas de Animais/anatomia & histologia , Animais , Brasil , Caraciformes/anatomia & histologia , Caraciformes/genética , Colômbia , Pesqueiros/organização & administração , Sistema da Linha Lateral/anatomia & histologia , Funções Verossimilhança , Maxila/anatomia & histologia , Mitocôndrias/genética , Filogenia , Pigmentação , Distribuição de Poisson , Rios , Alinhamento de Sequência , Software , Coluna Vertebral/anatomia & histologia , Terminologia como AssuntoRESUMO
The insects of subfamily Triatominae exhibit many morphological features used for taxonomic identification. In some species, however, these features are very similar. The authors have proposed by first time the description of the structure referred as urotergite I process. The objective of the study was analyse the use of urotergite I process in the species of the genus Triatoma as a taxonomic feature that may contribute to the more precise and correct identification of these Trypanosoma cruzi Chagas, 1909 vectors. Scanning electron microscopy (SEM) was used to describe the structure of urotergite I process in ten Triatoma (Hemiptera, Reduviidae, Triatominae) species: Triatoma brasiliensis Neiva, 1911; Triatoma circummaculata Stål, 1859; Triatoma infestans (Klug, 1834); Triatoma maculata (Erichson, 1848); Triatoma pseudomaculata Corrêa & Espínola, 1964; Triatoma rubrovaria (Blanchard, 1843); Triatoma sordida (Stål, 1859); Triatoma tibiamaculata (Pinto, 1926); Triatoma vitticeps (Stål, 1859) and Triatoma wygodzinskyi Lent, 1951. The morphological description of the urotergite I process reflects the taxonomic value of the structure for separating and identifying species of ten specimens of the genus Triatoma. The morphological pattern of the urotergite I process on these ten species was compared, and interspecific variability was observed. We suggest the use of the urotergite I process as a complementary character to identify insects of the subfamily Triatominae. In the future, the use of the urotergite I process in dichotomic keys to identify triatomines may contribute to the improvement of the entomological surveillance of Chagas' disease.
Assuntos
Escamas de Animais/anatomia & histologia , Escamas de Animais/ultraestrutura , Doença de Chagas/transmissão , Insetos Vetores/anatomia & histologia , Insetos Vetores/classificação , Triatoma/anatomia & histologia , Triatoma/classificação , Animais , Brasil , Classificação , Trypanosoma cruzi/isolamento & purificaçãoRESUMO
Ectothermic vertebrates are sensitive to thermal fluctuations in the environments where they occur. To buffer these fluctuations, ectotherms use different strategies, including the integument, which is a barrier that minimizes temperature exchange between the inner body and the surrounding air. In lizards, this barrier is constituted by keratinized scales of variable size, shape and texture, and its main function is protection, water loss avoidance and thermoregulation. The size of scales in lizards has been proposed to vary in relation to climatic gradients; however, it has also been observed that in some groups of Iguanian lizards it could be related to phylogeny. Thus, here, we studied the area and number of scales (dorsal and ventral) of 60 species of Liolaemus lizards distributed in a broad latitudinal and altitudinal gradient to determine the nature of the variation of the scales with climate, and found that the number and size of scales are related to climatic variables, such as temperature and geographical variables as altitude. The evolutionary process that best explained how these morphological variables evolved was the Ornstein-Uhlenbeck model. The number of scales seemed to be related to common ancestry, whereas dorsal and ventral scale areas seemed to vary as a consequence of ecological traits. In fact, the ventral area is less exposed to climate conditions such as ultraviolet radiation or wind and is, thus, under less pressure to change in response to alterations in external conditions. It is possible that scale ornamentation, such as keels and granulosity, may bring some more information in this regard.
Assuntos
Escamas de Animais/anatomia & histologia , Clima , Lagartos/anatomia & histologia , Escamas de Animais/fisiologia , Animais , Evolução Biológica , Regulação da Temperatura Corporal , Lagartos/fisiologia , Filogenia , Especificidade da EspécieRESUMO
A re-evaluation of the armoured catfish species of Hypostomus in the Rio Jaguaribe, north-eastern Brazil, was prompted by the discovery of specimens with pale spots on a dark background collected from that basin c. 1936 and deposited at the Academy of Natural Sciences of Philadelphia. Recent field collections in the Rio Jarguaribe basin confirmed the presence of the pale-spotted specimens and its distinctiveness as a new species. Hypostomus sertanejo n. sp. is diagnosed from other species of Hypostomus by having fins and dermal-plated regions of head and body with pale spots or vermiculations on darker background, teeth slender, asymmetrically bicuspid and numerous (34-75) on dentary and premaxilla, depressed dorsal-fin spine not reaching adipose spine, unbranched pectoral-fin spine longer than unbranched pelvic-fin ray, seven branched dorsal-fin rays and one (rarely two) predorsal plate(s) bordering supraoccipital. Ancistrus salgadae Fowler 1941 is hypothesized to be a junior synonym of Hypostomus carvalhoi (Miranda-Ribeiro, 1937), a dark-spotted Hypostomus described from the Rio Granjeiro, a tributary to the upper Rio Salgado.
Assuntos
Peixes-Gato/anatomia & histologia , Nadadeiras de Animais/anatomia & histologia , Escamas de Animais/anatomia & histologia , Animais , Brasil , Peixes-Gato/classificação , Ecossistema , Pigmentação da Pele , Dente/anatomia & histologiaRESUMO
The fish body is entirely covered by a thin, smooth and glandular epidermis, closely attached to the scales inserted on the dermis. The descriptive work on this tissue dates to twenty or thirty years ago, bears very little photographic record and does not focus on the scale epithelium, despite the fact that it is in direct contact with the environment. Thereupon, the present study characterizes the scale epithelium of Prochilodus lineatus, a robust species of fish. The observations show that the scale is completely covered by epithelium thicker on the proximal end of the scale, multilayered on the dorsal surface and undifferentiated on the ventral surface, and covered by mucous producing cells, mostly acid mucous. The scale is formed by plywood-like collagen matrix of collagen type III and supported by a network of elastic fibers on the ventral face. Differentiated cellular types are present, such as club cells, considered to be responsible for the release of alarm substances, which suggests possible use in environmental assessment as a non-invasive technique.(AU)
O corpo dos peixes é inteiramente coberto por uma epiderme fina, lisa e grandular intimamente aposta às escamas inseridas na derme. Os trabalhos descritivos sobre este assunto datam de vinte ou trinta anos atrás e possuem pouco registro fotográfico, além de não se focarem no epitélio da escama, apesar do fato de este estar em contato direto com o ambiente. Portanto, o presente estudo pretende caracterizar o epitélio das escamas de Prohilodus lineatus, uma espécie de peixe robusto. As observações mostram que a escama é completamente recoberta por epitélio, mais grosso na extremidade proximal da escama, estratificado na superfície dorsal, indiferenciado na superfície ventral e coberto por células mucosas, principalmente de muco de ácido. A escama é formada por uma matriz de colágeno de estrutura semelhante a madeira compensada de colágeno tipo III e se apóia em uma rede de fibras elásticas na superfície ventral. Tipos celulares diferenciados são presentes, como células club, consideradas responsáveis pela liberação de substâncias de alarme, o que sugere possível uso como técnica não invasiva para monitoramento ambiental.(AU)