First record of the association of the weevil Loncophorus longinasus with the fruit of munguba, Pseudobombax munguba in Central Amazonia, Brazil

We report the first record of occurrence of Loncophorus longinasus in fruits of munguba, Pseudobombax munguba, in the state of Amazonas, Brazil. Some morphological and biological aspects of L. longinasus are presented. Adults were obtained through natural emergence from munguba fruits that opened for seed dispersal. The fruits had perforations leading to galleries through the exocarp. Inside the fruit, larvae were found at the seed insertion points on the central seed attachment structure. The pupae developed in a cocoon at the same structure and turned mature simultaneously with the capsule opening. Together with the larvae, the presence of ants (Pseudomyrmex sp.) was observed, that apparently maintained the galleries open for access and feeding on larval exudates. (AU)

First record of the association of the weevil Loncophorus longinasus with the fruit of munguba, Pseudobombax munguba in Central Amazonia, Brazil / Primeiro registro da associação do gorgulho Loncophorus longinasus ao fruto de munguba, Pseudobombax munguba, na Amazônia Central, Brasil

We report the first record of occurrence of Loncophorus longinasus in fruits of munguba, Pseudobombax munguba, in the state of Amazonas, Brazil. Some morphological and biological aspects of L. longinasus are presented. Adults were obtained through natural emergence from munguba fruits that opened for seed dispersal. The fruits had perforations leading to galleries through the exocarp. Inside the fruit, larvae were found at the seed insertion points on the central seed attachment structure. The pupae developed in a cocoon at the same structure and turned mature simultaneously with the capsule opening. Together with the larvae, the presence of ants (Pseudomyrmex sp.) was observed, that apparently maintained the galleries open for access and feeding on larval exudates.(AU)

Este é o primeiro registro de ocorrência de Loncophorus longinasus em frutos da árvore munguba, Pseudobombax munguba, no Estado do Amazonas, Brasil. Alguns aspectos morfológicos e biológicos de L. longinasus são apresentados. Adultos foram obtidos quando emergiam naturalmente durante a abertura do fruto da munguba para a dispersão das sementes. Os frutos apresentaram perfurações que formavam galerias através do exocarpo. Dentro do fruto, foram encontradas larvas em pontos de inserção de sementes na estrutura central. Pupas foram encontradas em casulos na mesma estrutura central, e se transformaram em adultos simultaneamente com a abertura da cápsula. Junto às larvas, detectamos a presença de formigas (Pseudomyrmex sp.), que possivelmente mantêm abertas as galerias no exocarpo para acesso e consumo dos exsudatos das larvas.(AU)

Acacia trees with parasitic ants have fewer and less spacious spines than trees with mutualistic ants.

Obligate ant-defended plants provide food and shelter in exchange for protection against herbivores. Mesoamerican acacia trees have an obligate ant mutualism, but parasitic non-defending ants can also nest on the tree. We assessed whether rewards corresponded to ant defense within a plant species. As we expected, we found that parasite-inhabited trees had fewer swollen spines than ant-defended trees. Spine diameter was smaller in parasite-inhabited plants, but there were no differences in spine length, suggesting that spines serve as mechanical protection against herbivory. Parasite-inhabited plants may have reduced rewards because of plant differences when establishing, a plastic response to limited resources, or differential energy allocation when sensing the lack of defense.

Ontogenetic trajectories of direct and indirect defenses of myrmecophytic plants colonized either by mutualistic or opportunistic ant species.

Myrmecophytic plants are expected to produce greater direct defenses when young and switch towards indirect defenses once they reach the size and vigor to produce enough rewards for their ant mutualists. The presence of opportunistic ant species, however, is likely to promote the variation in these ontogenetic trajectories. When plants do not obtain benefits from ants, they cannot rely on this indirect defense. Hence, the expression of direct defenses is expected to remain constant or even increase during the development of plants colonized by opportunistic ants, whereas a reduction in resource allocation to indirect defenses should be observed. To assess if myrmecophytic plants adjust their ontogenetic trajectories in defense as a function of the colonizing ant species, we estimated direct and indirect defenses at four ontogenetic stages of the myrmecophytic plant Vachellia hindsii colonized by either mutualistic or opportunistic ant partners. We report that cyanogenic potential decreased while leaf thickness and the production of sugar in extrafloral nectaries increased along plant development. The magnitude of these ontogenetic changes, however, varied as a function of the identity of the colonizing ants. As expected, when colonized by opportunistic ants, plants produced more direct defenses and reduced the production of rewards. We suggest that facultative changes in the expression of ontogenetic trajectories in direct and indirect defenses could be a mechanism to reduce the fitness costs associated with opportunistic interactions.

Specialization and group size: brain and behavioural correlates of colony size in ants lacking morphological castes.

Group size in both multicellular organisms and animal societies can correlate with the degree of division of labour. For ants, the task specialization hypothesis (TSH) proposes that increased behavioural specialization enabled by larger group size corresponds to anatomical specialization of worker brains. Alternatively, the social brain hypothesis proposes that increased levels of social stimuli in larger colonies lead to enlarged brain regions in all workers, regardless of their task specialization. We tested these hypotheses in acacia ants (Pseudomyrmex spinicola), which exhibit behavioural but not morphological task specialization. In wild colonies, we marked, followed and tested ant workers involved in foraging tasks on the leaves (leaf-ants) and in defensive tasks on the host tree trunk (trunk-ants). Task specialization increased with colony size, especially in defensive tasks. The relationship between colony size and brain region volume was task-dependent, supporting the TSH. Specifically, as colony size increased, the relative size of regions within the mushroom bodies of the brain decreased in trunk-ants but increased in leaf-ants; those regions play important roles in learning and memory. Our findings suggest that workers specialized in defence may have reduced learning abilities relative to leaf-ants; these inferences remain to be tested. In societies with monomorphic workers, brain polymorphism enhanced by group size could be a mechanism by which division of labour is achieved.

A catalogue of the Pseudomyrmecinae ants type specimens (Hymenoptera, Formicidae) deposited in the Museu de Zoologia da Universidade de São Paulo, Brazil

This catalogue lists the type specimens of 37 species of Pseudomyrmecinae ants deposited in the Hymenoptera Formicidae collection of the Museu de Zoologia da Universidade de São Paulo, which holds types of the only two genera that occur in the Neotropics, Pseudomyrmex Lund and Myrcidris Ward. We record the label information, condition of the specimens, nomenclatural changes, type status, and provide an index of the listed taxa.

Este catálogo lista espécimes tipos de 37 espécies de formigas Pseudomyrmecinae depositadas na coleção de Formicidae da seção de Hymenoptera do Museu de Zoologia da Universidade de São Paulo, e que pertencem aos dois gêneros que ocorrem na Região Neotropical, Pseudomyrmex Lund e Myrcidris Ward. São apresentados os dados dos rótulos, estado de conservação dos exemplares, mudanças nomenclaturais, status taxonômicos e um índice para os táxons catalogados.

A catalogue of the Pseudomyrmecinae ants type specimens (Hymenoptera, Formicidae) deposited in the Museu de Zoologia da Universidade de São Paulo, Brazil

This catalogue lists the type specimens of 37 species of Pseudomyrmecinae ants deposited in the Hymenoptera Formicidae collection of the Museu de Zoologia da Universidade de São Paulo, which holds types of the only two genera that occur in the Neotropics, Pseudomyrmex Lund and Myrcidris Ward. We record the label information, condition of the specimens, nomenclatural changes, type status, and provide an index of the listed taxa.

Este catálogo lista espécimes tipos de 37 espécies de formigas Pseudomyrmecinae depositadas na coleção de Formicidae da seção de Hymenoptera do Museu de Zoologia da Universidade de São Paulo, e que pertencem aos dois gêneros que ocorrem na Região Neotropical, Pseudomyrmex Lund e Myrcidris Ward. São apresentados os dados dos rótulos, estado de conservação dos exemplares, mudanças nomenclaturais, status taxonômicos e um índice para os táxons catalogados.