Resumo em Inglês:

The parasite paradox arises from the dual observations that parasites (broadly construed, including phytophagous insects) are resource specialists with restricted host ranges, and yet shifts onto relatively unrelated hosts are common in the phylogenetic diversification of parasite lineages and directly observable in ecological time. We synthesize the emerging solution to this paradox: phenotypic flexibility and phylogenetic conservatism in traits related to resource use, grouped under the term ecological fitting, provide substantial opportunities for rapid host switching in changing environments, in the absence of the evolution of novel host-utilization capabilities. We discuss mechanisms behind ecological fitting, its implications for defining specialists and generalists, and briefly review empirical examples of host shifts in the context of ecological fitting. We conclude that host shifts via ecological fitting provide the fuel for the expansion phase of the recently proposed oscillation hypothesis of host range and speciation, and, more generally, the generation of novel combinations of interacting species within the geographic mosaic theory of coevolution. Finally, we conclude that taxon pulses, driven by climate change and large-scale ecological perturbation are drivers of biotic mixing and resultant ecological fitting, which leads to increased rates of rapid host switching, including the agents of Emerging Infectious Disease.

Resumo em Inglês:

The effectiveness of auditory signals for long distance communication depends on environmental, biological and behavioral factors. Because the environment is not homogenous, it is expected that vocalizing animals would emit signals from locations (perches) that would facilitate call propagation and perception. Perching behavior has been widely documented in birds, but not in primates. The aim of this study was to ascertain whether golden lion tamarins - Leontopithecus rosalia (Linnaeus, 1766) - emit long calls from places (perch) within the forest strata that are higher above the ground with respect to places used for baseline behaviors. We compared the forest stratum (upper, middle and lower strata) and habitat type (hill, swamp and lowland forests) used for long calls with those used for other behaviors. The focal animal technique (n = 4) of 10 minutes with instantaneous sampling at two minutes were used if the subjects were not emitting long calls, and the all-occurrences technique if a focal individual emitted a two-phrase long call. Golden lion tamarins used all strata in all habitat types, including the ground, when they were not emitting long calls, but vocalized long calls most often from the upper strata, just underneath the canopy, in the three habitats studied. From a total of 29 bouts of long calls, 21 were initiated by individuals that were in the lower stratum; however, these individuals subsequently migrated to the upper stratum, while still vocalizing. Calling from the upper strata of the forest, just underneath canopy could improve sound transmission, perception, visual contact or a combination of these types of communication. Based on these considerations, we hypothetize that by placing themselves in the upper strata of the forest when emitting calls, golden lion tamarins enhance their likelhood to locate other callers, not only be improving sound reception, but also by increasing their chances to make visual contact with them.

Resumo em Inglês:

Information on the diet of Anilius scytale is provided based on the analysis of 162 specimens from the Brazilian Amazonia. Amphisbaenians (Aulura anomala Barbour, 1914; Leposternon polystegumn [Duméril, 1951] and Amphisbaena sp.), which are highly specialized for a fossorial life, accounted for 81.25% of the recorded items, followed by snakes - Anilius scytale (Linnaeus, 1758), and Tantilla melanocephala (Linnaeus, 1758): 12.5% - and caecilians - Caecilia cf. gracilis Shaw, 1802: 6.25%. We found a positive, although not significant, relationship between the snout-vent length of A. scytale and the total length of the prey and a tendency for smaller specimens to ingest proportionately larger prey. Anilius scytale forages mainly on the ground, at night, as well as in aquatic environments. The non-selective capture of either proportionately large or small prey by A. scytale may reflect the opportunistic nature of the encounters. A tendency of the juveniles of this species to ingest proportionately larger prey may be associated with either a low availability of prey with a size compatible to that of the juveniles, or with their inexperience in selecting prey. Ingestion of prey headfirst may be an attempt to minimize the risk of injury the prey could cause through their rigid, pointed and sharp structures or powerful bites.

Resumo em Inglês:

The habitat use and feeding habits of a set of nektonic fish species often found in small low-gradient streams in Brazil were investigated. The core species in the present study was Knodus moenkhausii (Eigenmann & Kennedy, 1903), the most abundant of five species in the nektonic guild. Records of the species in 22 streams indicate that K. moenkhausii is associated, on a mesohabitat scale, with runs, and on a microhabitat scale, with sandy bottoms, intermediate depth, and open sites without coverage or submerged vegetation. During snorkeling observations, two additional nektonic registered species showed spatial segregation from K. moenkhausii with respect to foraging microhabitats. Feeding habits of the observed nektonic species were significantly correlated with riparian vegetation. The six species studied appear to use different resources, as suggested by a non-metric ordination of diet, and sites with characteristic riparian vegetation. The studied species may be considered generalists with a tendency to insectivory, with K. moenkhausii feeding on the widest variety of resources. Such opportunism explains its ability to successfully occupy instream habitats with low complexity.

Resumo em Inglês:

Ischnocnema (Brachycephalidae) includes many species that are important members of the leaf litter frog communities in the Atlantic Rainforest of Brazil. Ischnocnema parva (Girard, 1853) is endemic to the Atlantic Rainforest biome and is restricted to the forests of southeastern Brazil. Currently, the available information about the ecology of I. parva is scarce. We studied the diet, the habitat use, reproduction and density of I. parva in an area of Atlantic Rainforest at the Concórdia mountain range, Rio de Janeiro. Individuals of I. parva were captured in April 2005 using different sampling methods: time constrained search (transects), plots of 5 x 5 m (25 m²) on the litter, and pitfall traps with drift fences. We found 240 frogs; 35 females and 205 males. Females (mean SVL = 19.1 mm) were significantly larger (F1,238 = 143.016, R² = 0.375, p < 0.001) than males (13.2 mm). The species preyed mainly on arthropods, with ants and isopods being the most important items, both showing high values of importance index (Ix = 50.0 and 26.7, respectively). Ischnocnema parva is a terrestrial species whose preferential microhabitat at the Serra da Concórdia was the litter of the forest floor (78.7%). The activity was predominantly crepuscular-nocturnal and the estimated density of I. parva was 24.9 ind/100 m². For the eight ovigerous females captured, the mean number of mature oocytes per female was 25 (range: 22-30) and the oocyte mean diameter was 1.11 mm (N = 40 oocytes). Oocyte number increased with female body size (R² = 0.504, F1,6 = 6.107, p < 0.05, N = 8), indicating that as females increase in size they produce larger clutches. Some ecological aspects such as diet and microhabitat use were similar to that observed for an insular population of I. parva, whereas reproductive traits differed. Thus, long term studies are necessary to understand the extent to which these differences are explained by environmental factors.

Resumo em Inglês:

The thin-spined porcupine Chaetomys subspinosus (Olfers, 1818) is a species endemic to the extremely disturbed and fragmented Brazilian Atlantic forest. Little is known about its natural history. We analyzed the preferences of porcupine diurnal roost and home range, based on one relocated adult male that was radio-monitored during 1999. The individual was captured in the urban zone of Santa Teresa, Brazil, and relocated to a forest reserve 6 km from the capture site. The thin-spined porcupine feeds only on leaves. It prefers intermediate forest stratum (6-15 m of height) for roosting during daytime, generally using inclined branches with a diameter of 2 to 5 cm. Most observations indicated a prehensile tail position. Home range was relatively large (15.81 ha) for an arboreal animal of this size and new areas were still being explored after five months of monitoring.

Resumo em Inglês:

Despite limited natural dispersal, some species of ascidians can be transported vast distances via oceanic petroleum platforms, ship hulls and ballast water and therefore may be good indicators of bioinvasion. Usually non indigenous species (NIS) are abundant in harbors. This is caused in part because of the higher propagule delivery rate in these areas. An alternative explanation of why invasion is enhanced in harbor and marinas is that environmental degradation commonly found in these habitats favors the establishment of NIS. Most surveys for introduced species were not comprehensive and targeted mainly ports and marinas. Angra dos Reis is an excellent system that provides an opportunity to compare the potential distribution of introduced and native species of Ascidiacea between port and natural environments. Here, we compared the colonization of experimental subtidal plates placed in harbors and marinas with the colonization of plates placed in nearby natural areas. With 27 taxa (15 identified to species), species richness was greater in port environments (25 versus 8). Six taxa were common to both environments while 19 taxa were exclusively found in ports. Among the identified species in ports, three were introduced, five were cryptogenic and only one was native. Only three species were found exclusively in the natural sites and all were cryptogenic. The presence of introduced species only in the port areas of Angra dos Reis reinforces the need for continued, periodic monitoring in the region for early detection of new, potentially invasive, species as well as for better understanding of abnormal population growth of the already known species. Management to reduce the transfer of exotics to natural habitats must be implemented.

Resumo em Inglês:

Gastropod shells occupied by hermit crabs are an important attachment substrate for epifauna, and these shells are often damaged. The present study aimed to characterize the epibionts and extent of damage for gastropod shells occupied by the hermit crab Loxopagurus loxochelis (Moreira, 1901). Samples were collected monthly over a period of one year (from July 2002 through June 2003), in the Caraguatatuba and Ubatuba regions, on the northern coast of São Paulo, Brazil. The sampling was performed using a fishing boat equipped with double-rig nets. The shells were identified and weighed. Loxopagurus loxochelis occupied 14 gastropod shell species in Caraguatatuba and five in Ubatuba. In the two areas, approximately 55% of these gastropod shells bore epibionts, and a significantly large number (p < 0.05) showed no damage. The presence of epibionts did not significantly change the mean weight of shells. This cover may provide camouflage to the animals when they are associated with the sandy substrate, which possibly affects the occupancy of the shells by the hermit crabs. Undamaged shells may reflect a high availability of shells in good condition in the environment.

Resumo em Inglês:

The gross morphology of foregut was investigated and described in detail for four freshwater crab species: a pseudothelphusid, Fredius reflexifrons (Ortmann, 1897) and three trichodactylids - Sylviocarcinus pictus (H. Milne-Edwards, 1853), Valdivia serrata White, 1847, and Dilocarcinus septemdentatus (Herbst, 1783). In general, the gastric mills of freshwater crabs showed a similar degree of complexity in relation to other marine species of Anomura and Brachyura previously described in the literature. However, significant morphological differences were observed among the analyzed species, as in ossicle numbers, features and connection types. A total of 38 ossicles were described for S. pictus and V. serrata and 37 ossicles for D. septemdentatus and F. reflexifrons, respectively. The latter species can be distinguished from the others by the presence of a wide cardiac sac resembling two sacs. Most of the ossicles were connected through a rigid connection, and few ossicles were fused. The degree of calcification varied little among the studied species. The differences found among the species suggest that the morphological aspects of the foregut may be useful in the identification of similar species.

Resumo em Inglês:

The original description of Temnocephala iheringi Haswell, 1893 was based on specimens collected by Hermann von Ihering from undetermined ampullariid apple snails, which at that time were identified as Ampullaria sp., and sent to William H. Haswell, with the type locality simply indicated as Brazil. The type specimens studied by Haswell were not found in the scientific collections of Brazil, Europe or Australia, and should be considered lost. In 1941, Pereira & Cuocolo collected specimens from apple snails, identified as Pomacea lineata (Spix in Wagner, 1827), at two localities (Guaicurús and Salobra) in the state of Mato Grosso do Sul, central Brazil. These specimens could not be located either and should, thus, be considered lost as well. Pomacea canaliculata (Lamarck, 1822), the main host of T. iheringi in southern Brazil, is known to have a geographical distribution that reaches Uruguay and 400 km beyond the province of Buenos Aires, Argentina. Three hundred and one mollusks were collected from 1999 to 2007. Temnocephalans found in the pallial cavity presented a greenish body pigmentation (adults) and lacked eye pigment of any color, including the red-eye pigment, typical of Neotropical species of Temnocephala Blanchard, 1849; straight cirrus, with a thick band at base of the introvert' swelling; and a single, circular, asymmetric vaginal sphincter, wider in diameter in the posterior portion. As the species occurs concurrently with two other species, at least in P. canaliculata from Rio Grande do Sul, the eggs of T. iheringi could not be reliably distinguished. A redescription of the species is provided. A comparison of data from the present work with those of earlier papers published on T. iheringi from Argentina showed that the Argentinean specimens had the smallest measurements.

Resumo em Inglês:

Coenosiinae is an important component of the Neotropical Muscidae diversity due to the high diversity of species and high population numbers. Based on the examination of type-specimens of some species of Coenosiini, the following taxonomic changes are proposed: Neodexiopsis medinai Snyder, 1957 stat. rev., Pilispina xanthogaster (Albuquerque, 1958) comb. nov., Pilispina differa Couri & Carvalho, 1999 is a junior synonym of Pilispina pilitibia Albuquerque, 1954, Neodexiopsis barbiventris Couri & Albuquerque, 1979 is a junior synonym of Neodexiopsis flavipalpis Albuquerque, 1956 and a neotype is proposed for Coenosia latitibia Albuquerque 1957. In all cases, remarks include reevaluation of relevant characters.

Resumo em Inglês:

Nine new species of Phenacogaster Eigenmann, 1907 are described: Phenacogaster capitulatus sp. nov. from the Neshuya River system, Ucayali River basin; Phenacogaster maculoblongus sp. nov. from the upper Cuyuni River, and tributaries of the lower Orinoco River; Phenacogaster napoatilis sp. nov. from the Napo River system, upper Amazon River basin; Phenacogaster ojitatus sp. nov. from the Xingu River system; Phenacogaster prolatus sp. nov. from the Orinoco River, canal Casiquiare and upper and middle Negro River; Phenacogaster retropinnus sp. nov. from the Negro, Madeira and Xingu river systems; Phenacogaster simulatus sp. nov. from the Potaro River, Essequibo drainage; Phenacogaster wayampi sp. nov. from the Oiapoque River, and Phenacogaster wayana sp. nov. from the Corantijn (Suriname), Maroni, Mana, Sinnamary and Approuague rivers (French Guiana). The geographic distribution of P. megalostictus, previously recorded for the Negro River, Amazon River system, is restricted to the Essequibo River system, Guiana. The distribution of P. carteri, previously known only from the type-locality (Cuyuni River, Guyana), is extended to the lower Orinoco River. The reduction of the latero-sensory canal, mentioned in the literature as an autapomorphy for P. tegatus was observed in three additional species of Phenacogaster. The posterior humeral spot, found only in P. tegatus, is herein considered autapomorphic for the species. Diagnoses are given for previously described species based on the analysis of type material and additional specimens, and a key to the species of the genus is provided.

Resumo em Inglês:

Gadila elongata comb. nov. was described in 1920 from the northern Gulf of Mexico. Until recently, it was only known from the type locality. Herein we present the first record of G. elongata from Brazil (Northeast coast, Ceará state, collected at 177 m) and a morphometrics analysis of the Brazilian species of Gadila. A multivariate Discriminant Function Analysis, based on nine shell morphometric variables (length, maximum diameter, length to maximum diameter ratio, distance of point of maximum diameter from anterior aperture, maximum curvature, anterior aperture height to anterior aperture width ratio, apical aperture height, apical aperture width and apical aperture height to apical aperture width ratio) enabled the distinction between all species studied. Comparisons of shell morphometrics show that length and length to maximum diameter ratio are the most important variables in the differentiation of Gadila species.

Resumo em Inglês:

Phylloicus monneorum sp. nov. is described and illustrated based on specimens collected in the Mantiqueira mountain range, Itatiaia, state of Rio de Janeiro, Brazil. The new species is the smallest within the genus. The male can be distinguished by the preanal appendages short, wide, flattened and with irregular margins, and by the deeply V-shaped tergum X. The female is also described and figured. The immature stages are unknown.

Resumo em Inglês:

The male of Dossenus guapore Silva, Lise & Carico, 2007 is described and illustrated for the first time, based on material from Bonito, Mato Grosso do Sul, Brazil. The spider genus Dossenus Simon, 1898 is distributed from Panama to southern Brazil and can be distinguished by the other known genera of Trechaleidae by the median dark brown band on the carapace that extends to the abdomen and by the spoon-like shape of the median apophysis of the male palpus. A new species of Dyrines Simon, 1903, D. brescoviti sp. nov., is described and illustrated based on material collected in Sergipe and Paraná, Brazil. The representatives of this spider genus are relatively small and can be distinguished from the other genera by the longitudinal dark brown bands on the legs. New records of Dyrines striatipes (Simon, 1898) are presented.