Cléa dos Santos Ferreira Mariano

Contribution of cocoa plantations to the conservation of native ants (Insecta: Hymenoptera: Formicidae) with a special emphasis on the Atlantic Forest fauna of southern Bahia, Brazil

By maintaining a forest-like structure, shaded cocoa plantations contribute to the conservation of ants that usually live in the soil, leaf litter or canopy of tropical forests. Here we synthesize the available information on the diversity and community structure of ants in shaded cocoa plantations in the Atlantic forest region of Brazil, compare ant assemblages in cocoa agroforests with forests and other forms of agriculture, and discuss how these shaded plantations contribute to the conservation of the ants in the Atlantic Forest region. We also discuss ants of economical importance and of special interest, including Camponotus, Dolichoderus, Gnamptogenys, Pachycondyla, Pseudomyrmex and other litter dwelling genera. We discuss the situation of the tramp ant Wasmannia auropunctata in the Bahian cocoa-producing region where it is considered as native, and that of the two cryptobiotic genera Thaumatomyrmex and Typhlomyrmex, as well as that of proven and possible endangered army ant and Ponerini species. A total of 192 ant species from four strata were found in extensive sampling of a cocoa plantation with a relatively simple shade canopy (comprised primarily of Erythrina). Species richness in the cocoa plantations corresponded roughly to that of low diversity native forests, and species composition of cocoa plantations was most similar to native habitats (forest and mangroves) while ant composition in other agricultural habitats was most similar to that of urban areas. Although occurrences of Wasmannia auropunctata were similar in cocoa plantations and forests, abundance of Thaumatomyrmex and Typhlomyrmex, generally thought to be rare ants, was relatively high in cocoa plantations. These results, from cocoa plantations with relatively simple shade, demonstrate the importance of cocoa for ant conservation in the Atlantic forest region of Brazil. It is likely that cocoa plantations with a greater number of vegetation strata and higher tree species richness (such as traditional cabruca plantations) provide even more important habitat for ants generally and for ant species of conservation concern.

As formigas como indicadores biológicos do impacto humano em manguezais da costa sudeste da Bahia

Mangroves are common in estuaries along the Atlantic coast of Brazil. Although plant diversity is low, this ecosystem supports a range of animals, offering some resources for non-aquatic organisms. Many insects live in mangroves and, between them, many ant species that are exclusively arboreous. Mangroves throughout the world suffer from high levels of human impact, and this is particularly true for southeastern Bahia, where land-uses include traditional crab and fish exploitation, urban development, refuse pollution, recreation, and timber extraction. The ants of 13 mangrove sites, representing a range of levels of human use, have been studied along 250 km of the southern Bahia littoral, between Itacaré and Porto Seguro. Ants were sampled both inside and on the periphery of the tidal zone, using entomological rainbow, baiting, collect of hollow branches and pit-fall. A total of 108 species have been collected, with the richest genera being Camponotus and Pseudomyrmex, and the most frequent belonging to the genera Azteca and Crematogaster. The ant community living on the periphery of mangrove areas is rather homogeneous regardless of the degree of environmental perturbation, but varies markedly with the disturbance inside the mangroves themselves. The evolution of richness of the both communities, mangrove and periphery, is negatively related to the human effects, even limited to the periphery. Ant communities therefore have the potential to be useful as biological indicators of ecological impacts of land-use in these mangrove systems.

A biogeographical study of the threatened ant Dinoponera lucida Emery (Hymenoptera: Formicidae: Ponerinae) using a cytogenetic approach

Abstract.  1 Ants of the genus Dinoponera belong to a convergent group, in which there is no morphologically specialized caste of reproducing females and reproduction is by fertilized workers known as gamergates. Dinoponera lucida Emery, which is native to Brazilian Atlantic rain forest, is included on the official list of Brazilian fauna species threatened with extinction, due to habitat fragmentation, loss of their natural habitat and to peculiarities in their biology. 2 Karyotype variation was studied among D. lucida populations in the states of Bahia and Espirito Santo, Brazil. The cytogenetic study was carried out on brain ganglia and/or on male and/or female gonads. Banding techniques, such as sequential staining with DA/CMA3/DAPI fluorochromes and FISH, were also applied. 3 The diploid chromosome numbers ranged from 106 to 120. Variations in the karyotype were detected in the populations from Bahia, while in Espirito Santo the karyotypes were the same everywhere. Most of the chromosomes were small in size and acrocentric, except for a differentiated pair (AMt). This pair exhibited polymorphism in the different populations. 4 The karyotype variation detected in D. lucida suggested that the original population has previously been divided into two allopatric populations distributed in two different refugial areas of Atlantic rain forest in the early Quaternary. They probably developed in parallel and differentiated in karyotype composition. When the Atlantic rain forest regained its continuous distribution along with the Brazilian coast, the two groups came to occupy the continuous area of occurrence of the species that is seen today.

A Cytogenetic Approach to the Study of Neotropical Odontomachus and Anochetus Ants (Hymenoptera: Formicidae)

ABSTRACT Odontomachus (Latreille) and Anochetus (Mayr) (Hymenoptera: Formicidae: Ponerinae) are closely related pantropical genera of ponerine ants that share morphological and behavioral characteristics. A comparative study was carried out using conventional Giemsa staining, fluorochrome staining, and fluorescent in situ hybridization. Karyotypes revealed a higher stability in chromosome number among Odontomachus species than among Anochetus species. We observed a higher frequency of metacentric chromosomes in the karyotypes of Anochetus compared with the more common telocentrics of Odontomachus species. Differences in the localization of rDNA genes on chromosomes between the two genera also were verified, rDNA genes were found on telocentric and submetacentric chromosomes in Anochetus and on telocentric chromosomes in Odontomachus. Our cytogenetic results lend support to Browns hypothesis that Odontomachus has evolved from a lineage of Anochetus. The karyotype divergence of both genera can be explained by a model of evolution in which there is a tendency to the increase of chromosome number by centric fission. Supporting evidence for this hypothesis is discussed.

Contribution of Cytogenetics to the Debate on the Paraphyly of Pachycondyla spp. (Hymenoptera, Formicidae, Ponerinae)

We present evidence of the paraphyly of the ant genus Pachycondyla resulting from our cytogenetic studies on 29 populations in 18 species from Brazil and French Guyana. It is likely that karyotypes with a large number of chromosomes and comprising mostly small acrocentric chromosomes in species within the Pachycondyla stricto sensu group resulted from a succession of centric fission events. On the other hand, karyotypes with a small chromosome number comprising mostly metacentric chromosomes are also interpreted as little derived and tend to undergo centric fission. The karyotypes of the group Neoponera are more heterogeneous and probably undergo successive cycles of rearrangements tending to increase the chromosome number by centric fission. The apicalis and verenae complexes form two probable sister groups that evolved independently due to centric fissions (verenae) and pericentric inversions (apicalis). Our results reveal the karyotype diversity in the genus and reinforce the hypothesis on the paraphyly of Pachycondyla.

Dinoponera lucida Emery (Formicidae : Ponerinae): the highest number of chromosomes known in Hymenoptera

We report the remarkable karyotype of Dinoponera lucida, a Brazilian endemic ponerine ant. Its chromosome number is 2n=106, most of the chromosomes are acrocentric and of very small size, and the karyotype formula is 88A+18M. A chromosome pair of the AMt type is reported. This is the largest number of chromosomes reported for the Hymenoptera order until now.

Occurrence of pre-nucleolar bodies and 45S rDNA location on the chromosomes of the ant Mycocepurus goeldii (Forel) (Formicidae, Myrmicinae, Attini)

The ant Mycocepurus goeldii (Forel) is known for having a relict karyotype with low chromosome number and the present study help the understanding of this ant cytogenetics by describing the occurrence of pre-nucleolar bodies in their chromosomes using impregnation with silver nitrate (Ag-NOR) and the location of 45S rDNA sites by means of the FISH (fluorescent in situ hybridization) technique. Several spots were observed surrounding all chromosomes when submitted to the Ag-NOR technique. These unusual markings were observed in both chromatids of metaphase and early anaphase chromosomes, and are associated to the presence of pre-nucleolar bodies, allowing the observation of the phenomenon of nucleologenesis. Although recent studies have shown that all chromosomes of M. goeldii exhibit centromeric or pericentromeric markings for the CMA(3) fluorochrome, the FISH technique indicated the presence of 45S rDNA in only one pair of chromosomes that differed in the number of CMA(3) markings observed for this species, pointing that the other markings observed with this fluorochrome do not match the sequences in ribosomal genes.

The karyotypes of Gigantiops destructor (Fabricius) and other ants from French Guiana (Formicidae)

Abstract The aim of this study, which was conducted in French Guiana, was to characterize the karyotypes of nine ant species belonging to the genera Anochetus, Apterostigma, Cyphomyrmex, Camponotus, Gigantiops, Myrmicocrypta, Odontomachus and Pseudomyrmex, and to compare them with published data. We present the first descriptions of the karyotypes of Gigantiops destructor (Fabricius), an endemic Formicinae of the Amazonian region, which is the only living species in the tribe Gigantiopini, and of a species from the poorly-known cryptic genus Myrmicocrypta, which belongs to the Myrmicinae tribe Attini.

Epidermal Glands in the Abdomen of a Basal Ant Dinoponera lucida (Formicidae: Ponerinae)

The basal ant Dinoponera (Hymenoptera: Ponerinae) has lost the morphologic queen caste so that all females may be potential reproductive individuals, and the nestmate recognition results from cuticular hydrocarbons cues. However, data about the origin of that substance in Ponerinae ants are scarce. This study reports the occurrence of epidermal glands in the abdomen of the ant Dinoponera lucida. In this ant, the epidermis of the abdominal sternites has tall cells with well‐developed nucleus contrasting with flattened and collapsed epidermis in the tergites, suggesting a glandular function in the epidermis of the sternites. The possible role of the glandular epidermis in the synthesis of cuticular hydrocarbons for the nestmate recognition is discussed. Microsc. Res. Tech., 2009.

Cytogenetic characterization of the ant Trachymyrmex fuscus Emery, 1934 (Formicidae: Myrmicinae: Attini) with the description of a chromosomal polymorphism

Summary The genus Trachymyrmex is a key group in the tribe Attini because of its close phylogenetic relationship to leaf-cutter ants, Acromyrmex and Atta. Cytogenetic data are only available for five taxa of Trachymyrmex, with chromosome numbers of 2n = 12, 18, 20 and 22, and morphology with predominantly metacentric chromosomes. The aim of the present study was to characterize the karyotype of the ant Trachymyrmex fuscus Emery, 1934, by means of the number and morphology of its chromosomes, heterochromatin pattern, CMA3 and DAPI fluorochromes in the population of two nests collected at Paraopeba, state of Minas Gerais, Brazil. Nineteen females presented 2n = 18 chromosomes (16m + 2sm) and a single male presented n = 9 (8m + 1sm). A size chromosomal polymorphism involving the short arm of the submetacentric pair was confirmed by statistical analysis, with three character conditions: heterozygous SB (with a difference in size between the short arms), standard SS (smaller short arms) and homozygote BB (bigger short arms). In the first nest, both SB and SS workers were observed. The other nest contained heterozygous (SB), homozygous (BB), and a male carrying the B chromosome (larger size). The presence of heterochromatin on all centromeric and pericentromeric chromosomes of T. fuscus suggests that the size difference observed in the submetacentric pair in the SB and BB workers is not related to the heterochromatin but to a duplication of euchromatic regions through intra- or inter- chromosomal rearrangements. The fluorochrome CMA3 matched the C-banding markings, indicating that the heterochromatin is rich in GC base pairs. As far as we know, this is the first chromosomal polymorphism reported in the tribe Attini.