Roberta de Melo Valente

Evolutionary trends in derelomine flower weevils (Coleoptera : Curculionidae): from associations to homology

The host-plant associations and life histories of weevils in the pantropical tribe Derelomini are reviewed in light of new phylogenetic insights. The most immediate derelomine ancestor likely had a ‘special association’ with the inflorescences of palms (Arecaceae) involving pollination and oviposition into dispensable male flowers. Case studies of select genus groups show multiple historical forces driving their diversification. In the South and Central American genus Celetes, abundant host shifts are important, though clearly not enough to account for the existence of all species. Females of the Neotropical genus Staminodeus have remarkable morphogical and behavioural modifications for exploiting the staminodes of cyclanth (Cyclanthaceae) inflorescences. The evolution of males in this genus is mostly explained by sexual selection. Cyclanthura illustrates the potential of the weevils for colonising hosts with widely divergent inflorescence biologies, including arums (Araceae) in the genus Anthurium. Members of the Ganglionus–Systenotelus clade, in turn, are exclusively associated with the cyclanth genus Carludovica. A phylogenetic trend in this group to attack the plants’ seeds has led to a series of counteracting transformations in inflorescence morphology. Overall there were at least three independent secondary host shifts to dicots, including one in the taxonomically complex genus Phyllotrox. The results suggest that in this particular tribe of weevils, focusing on the homology of specific biological traits in individual lineages is more likely to produce new knowledge than a formalistic, large-scale approach.

Feeding ecology of Auchenipterichthys longimanus (Siluriformes: Auchenipteridae) in a riparian flooded forest of Eastern Amazonia, Brazil

Neste estudo foram investigados os habitos alimentares do bagre Auchenipterichthys longimanus coletados em rios da Floresta Nacional de Caxiuana (Amazonia Oriental, Brasil) ao longo de diferentes periodos hidrologicos (seco, enchendo, cheio e vazando). Foram coletados 589 especimes durante sete amostragens, entre julho de 2008 e julho de 2009, dos quais 74eram machos jovens, 177 machos adultos, 89 femeas jovens e 249 femeas adultas. A composicao da dieta, analisada pelo Indice de Importância Alimentar (IAi%) foi avaliada por um escalonamento multidimensional nao-metrico (nMDS) e pela analise de similaridade (ANOSIM), que incluiu 37 itens alimentares agrupados em nove categorias (insetos aquaticos, outros invertebrados aquaticos, fragmento de artropodes, peixe, fragmento de planta, sementes, insetos terrestres, outros invertebrados terrestrese vertebrados terrestres). Tambem foram obtidos a amplitude de nicho (Indice de Levins) e o Indice de Replecao (IR%) da dieta do bagre. Foram observadas diferencas na composicao da dieta entre os periodos hidrologicos, principalmente relacionada a estacao seca e cheia, mas nao houve variacao na composicao da dieta entre os sexos e maturidade. No periodo de cheia (especificamente no mes de marco/2009) o bagre mostrou uma alimentacao mais especialista enquanto que no periodo de seca (novembro/2008) os valores de amplitude de nicho classificaram-no com habitos mais generalistas quanto a alimentacao. A quantidade de alimentos ingeridos por A. longimanus com base no Indice de Replecao (IR%), nao diferiram significativamente entre o sexo e maturidade. No entanto, foram evidenciadas diferencas quando comparados os meses estudados. Estes resultados fornecem informacoes biologicas importantes sobre a ecologia trofica de peixes da familia Auchenipteridae. Tendo em vista a maior ocorrencia de itens aloctones na dieta deste bagre, esta pesquisa tambem reforca a importância das matas ciliares em ambientes criticos na manutencao e conservacao das populacoes selvagens de peixes na bacia amazonica.

Feeding ecology of Serrasalmus gouldingi (Characiformes: Serrasalmidae) in the lower Anapu River region, Eastern Amazon, Brazil

Studies on feeding ecology of fishes are important to understand the relationship between species and environmental seasonal variations. In tropical rivers, these relationships are mainly modeled by hydrological patterns. Thereby, this study aimed to assess the influence of fluviometric variation and life stage (juveniles and adults) in the feeding ecology of Serrasalmus gouldingi in the lower Anapu River region, located in Eastern Amazon, Para, Brazil. Specimens were collected bimonthly, considering four different hydrological periods. We assessed the diet composition, feeding intensity and niche breadth of the species. Thirty-two dietary items were identified and grouped into ten categories. A total of 279 stomachs were analyzed, showing a predominance of fish fragments, followed by fruits and seeds. The diet composition of S. gouldingi differed only between drought and flood season, although it did not differ between juveniles and adults. An increase in feeding intensity was recorded during the rise in the water level, with a lower feeding intensity observed during transitional season. Serrasalmus gouldingi showed lower niche breadth during flood season, attributed to the high consumption of fruits and seeds, presenting an omnivorous diet with high tendency towards piscivory. Although less evident than in other Amazon watersheds, the flood pulse in the lower Anapu River region is an important factor influencing the feeding ecology of the species.

Mauritinus seferi Bondar, 1960: bionomy, description of immature stages and redescription of adult (Coleoptera, Curculionidae)

Mature larvae of Mauritinus seferi Bondar, 1960 were collected in the mesocarp of murity palm (Mauritia flexuosa Linnaeus), in the State of Para, Brazil. Larvae were reared to pupa and adults in the laboratory. Mature larva and pupa are described and adult redescribed. Adult and immature are illustrated for the first time. Observations about bionomy are included and discussed.

The first Amazonian species of Andranthobius Kuschel (Coleoptera: Curculionidae), with records of new host palms for the genus.

Andranthobius setirostris sp. nov. is the first species of Andranthobius Kuschel described from the Amazon. It is distinguished from other species within the genus by an anterior obtuse tubercle on the lateral margin of the pronotum, the rostrum of the males with a lateroventral row of tubercles and comb of setae, and a much larger body. Adult specimens were originally collected in flowers of the palms Syagrus vermicularis Noblick and Syagrus cocoides Mart., and additional collections suggest that this association is specific. Both species of palms are recorded for the first time as host plants of Andranthobius.

The floral biology and reproductive system of Mauritia flexuosa (Arecaceae) in a restinga environment in northeastern Brazil

Studies of the floral biology of the buriti palm, Mauritia flexuosa, have presented conflicting results with respect to the mechanism of pollination, indicating either cantharophily or anemophily. To resolve this question, the floral biology of M. flexuosa was studied in a coastal restinga environment in northeastern Brazil. The reproductive system was studied experimentally, and floral visitors were collected by bagging inflorescences. In this environment, M. flexuosa, a dioecious species, has several gender-specific floral features that function to attract pollinators, especially beetles. The male flowers produce large amounts of pollen as a reward, and male and female inflorescences produce similar odors that attract pollinators to female flowers, which offer only a nectar secretion as a reward. When feeding on the female flowers, the visitors frequently come into contact with the stigmata. To increase the chances of pollination, the female flowers persist longer than the male ones, and the viability of the pollen grain is very high. A curculionid beetle species of the genus Grasidius was found to be an effective pollinator. We suspect that wind also contributes to the pollination of M. flexuosa in the study area, but in a relatively minor way.

Reproductive phenology of Mauritia flexuosa L. (Arecaceae) in a coastal restinga environment in northeastern Brazil

The buriti, Mauritia flexuosa, is the most common palm in Brazil, where it has considerable ecological and economic importance. However, few data are available on the phenology of the species, mainly in coastal restinga ecosystems. The present study monitored the reproductive phenology of M. flexuosa in the restinga of Barreirinhas, in the Brazilian Northeast, and investigated the relationship between phenophases and climatic variables. The presence/absence of flowers and fruits was recorded monthly in 25 individuals of each sex between August, 2009, and October, 2012. There was no difference in the phenology of male and female specimens, with flowering and fruiting occurring exclusively in the dry season. We believe that the specific abiotic characteristics of the study environment, such as the intense sunlight and availability of water in the soil, contribute to the reproductive success of M. flexuosa in the dry season, with consequent germination and establishment of seedlings occurring during the subsequent rainy season.

Damage by Homalinotus depressus in commercial coconut palm crops in the Amazonian region of Brazil

The coconut palm (Cocos nucifera L., Arecaceae) has great economic and social importance for many industrial and non-industrial products. Pests can reduce its productivity and cause its death. In 2005, larvae and adults of a Curculionidae were observed damaging the floral stalk of coconut palms in commercial plantations in the municipality of Moju, Pará State, in the Brazilian Amazon. Insects were identified as the black coconut bunch weevil, Homalinotus depressus (L.) (Coleoptera: Curculionidae: Cholini). This is the first report of this pest damaging coconut palms in Brazil.