Molecular Profile of the Brazilian Weaver Ant Camponotus textor Forel (Hymenoptera, Formicidae).

Camponotus textor Forel is, to date, the only weaver ant recorded from Brazil, and all existing studies on the species are restricted to describing its weaving and nesting behaviors. The aim of this work is to establish the molecular profile of the species. We sampled eight different colonies by sequencing mitochondrial genes (COI, transfer DNA (tRNA), and an intergenic spacer) and the nuclear gene 28S ribosomal DNA (rDNA). We then assessed haplotype diversity and also analyzed distribution patterns of this species based on the correlation between genetic and geographic distances. Our results provide an additional tool for species identification by identifying new regions that can be used as molecular markers for barcoding (such as the intergenic spacer (IGS) and tRNA-Leu). In addition, the phylogenetic analysis revealed that C. textor has features that could be associated with deep population divergences. We identified a wide range of mitotypes and three distinct groups, suggesting a possible reduction of gene flow between colonies.

Occurrence of three haplotypes of Linepithema micans (Forel) (Hymenoptera: Formicidae) in Southern Brazil.

Linepithema micans (Forel) (Hymenoptera: Formicidae) is reported to occur from eastern Brazil to central Argentina in pasture or grassland, forest and second growth riparian forest, nesting under stones, rotting wood, and sandy soil. However, information on this species is poor and its ecological interactions and role as pests are unknown. Linepithema humile (Mayr), a closely related species to L. micans, known as the Argentine ant, is native to South America, and was accidentally introduced to several regions of the world. Recent studies have shown that other related species, such as L. micans, could become as pestiferous as L. humile because of its phylogenetic proximity. Samples of L. micans from different habitats in Southern Brazil were characterized by sequencing of the mitochondrial DNA. Sequences were compared to previously obtained sequences from samples of L. humile and the genetic distance and differences in the tRNALeu structure were investigated. Our data identified three haplotypes of L. micans, two of which were observed in ant populations closely associated with the Brazilian ground pearl Eurhizococcus brasiliensis (Hempel) (Hemiptera: Margarodidae), a soil scale that is a serious pest of vineyards. The third haplotype was identified in ants from populations invading residences in urban habitats.

Coptotermes gestroi (Isoptera: Rhinotermitidae) in Brazil: possible origins inferred by mitochondrial cytochrome oxidase II gene sequences.

The Asian subterranean termite, Coptotermes gestroi, originally from northeast India through Burma, Thailand, Malaysia, and the Indonesian archipelago, is a major termite pest introduced in several countries around the world, including Brazil. We sequenced the mitochondrial COII gene from individuals representing 23 populations. Phylogenetic analysis of COII gene sequences from this and other studies resulted in two main groups: (1) populations of Cleveland (USA) and four populations of Malaysia and (2) populations of Brazil, four populations of Malaysia, and one population from each of Thailand, Puerto Rico, and Key West (USA). Three new localities are reported here, considerably enlarging the distribution of C. gestroi in Brazil: Campo Grande (state of Mato Grosso do Sul), Itajaí (state of Santa Catarina), and Porto Alegre (state of Rio Grande do Sul).

Molecular phylogeny and karyotype differentiation in Paratelmatobius and Scythrophrys (Anura, Leptodactylidae).

Paratelmatobius and Scythrophrys are leptodactylid frogs endemic to the Brazilian Atlantic forest and their close phylogenetic relationship was recently inferred in an analysis that included Paratelmatobius sp. and S. sawayae. To investigate the interspecific relationships among Paratelmatobius and Scythrophrys species, we analyzed a mitochondrial region (approximately 2.4 kb) that included the ribosomal genes 12S and 16S and the tRNAval in representatives of all known localities of these genera and in 54 other species. Maximum parsimony inferences were done using PAUP* and support for the clades was evaluated by bootstrapping. A cytogenetic analysis using Giemsa staining, C-banding and silver staining was also done for those populations of Paratelmatobius not included in previous cytogenetic studies of this genus in order to assess their karyotype differentiation. Our results suggested Paratelmatobius and Scythrophrys formed a clade strongly supported by bootstrapping, which corroborated their very close phylogenetic relationship. Among the Paratelmatobius species, two clades were identified and corroborated the groups P. mantiqueira and P. cardosoi previously proposed based on morphological characters. The karyotypes of Paratelmatobius sp. 2 and Paratelmatobius sp. 3 described here had diploid chromosome number 2n = 24 and showed many similarities with karyotypes of other Paratelmatobius representatives. The cytogenetic data and the phylogenetic analysis allowed the proposal/corroboration of several hypotheses for the karyotype differentiation within Paratelmatobius and Scythrophrys. Namely the telocentric pair No. 4 represented a synapomorphy of P. cardosoi and Paratelmatobius sp. 2, while chromosome pair No. 5 with interstitial C-bands could be interpreted as a synapomorphy of the P. cardosoi group. The NOR-bearing chromosome No. 10 in the karyotype of P. poecilogaster was considered homeologous to chromosome No. 10 in the karyotype of Scythrophrys sp., chromosome No. 9 in the karyotype of Paratelmatobius sp. 1, chromosome No. 8 in the karyotypes of Paratelmatobius sp. 2 and of Paratelmatobius sp. 3, and chromosome No. 7 in the karyotype of P. cardosoi. A hypothesis for the evolutionary divergence of these NOR-bearing chromosomes, which probably involved events like gain in heteochromatin, was proposed.

Low variation in ribosomal DNA and internal transcribed spacers of the symbiotic fungi of leaf-cutting ants (Attini: Formicidae)

Leaf-cutting ants of the genera Atta and Acromyrmex (tribe Attini) are symbiotic with basidiomycete fungi of the genus Leucoagaricus (tribe Leucocoprineae), which they cultivate on vegetable matter inside their nests. We determined the variation of the 28S, 18S, and 5.8S ribosomal DNA (rDNA) gene loci and the rapidly evolving internal transcribed spacers 1 and 2 (ITS1 and ITS2) of 15 sympatric and allopatric fungi associated with colonies of 11 species of leafcutter ants living up to 2,600 km apart in Brazil. We found that the fungal rDNA and ITS sequences from different species of ants were identical (or nearly identical) to each other, whereas 10 GenBank Leucoagaricus species showed higher ITS variation. Our findings suggest that Atta and Acromyrmex leafcutters living in geographic sites that are very distant from each other cultivate a single fungal species made up of closely related lineages of Leucoagaricus gongylophorus. We discuss the strikingly high similarity in the ITS1 and ITS2 regions of the Atta and Acromyrmex symbiotic L. gongylophorus studied by us, in contrast to the lower similarity displayed by their non-symbiotic counterparts. We suggest that the similarity of our L. gongylophorus isolates is an indication of the recent association of the fungus with these ants, and propose that both the intense lateral transmission of fungal material within leafcutter nests and the selection of more adapted fungal strains are involved in the homogenization of the symbiotic fungal stock.

Low variation in ribosomal DNA and internal transcribed spacers of the symbiotic fungi of leaf-cutting ants (Attini: Formicidae).

Leaf-cutting ants of the genera Atta and Acromyrmex (tribe Attini) are symbiotic with basidiomycete fungi of the genus Leucoagaricus (tribe Leucocoprineae), which they cultivate on vegetable matter inside their nests. We determined the variation of the 28S, 18S, and 5.8S ribosomal DNA (rDNA) gene loci and the rapidly evolving internal transcribed spacers 1 and 2 (ITS1 and ITS2) of 15 sympatric and allopatric fungi associated with colonies of 11 species of leafcutter ants living up to 2,600 km apart in Brazil. We found that the fungal rDNA and ITS sequences from different species of ants were identical (or nearly identical) to each other, whereas 10 GenBank Leucoagaricus species showed higher ITS variation. Our findings suggest that Atta and Acromyrmex leafcutters living in geographic sites that are very distant from each other cultivate a single fungal species made up of closely related lineages of Leucoagaricus gongylophorus. We discuss the strikingly high similarity in the ITS1 and ITS2 regions of the Atta and Acromyrmex symbiotic L. gongylophorus studied by us, in contrast to the lower similarity displayed by their non-symbiotic counterparts. We suggest that the similarity of our L. gongylophorus isolates is an indication of the recent association of the fungus with these ants, and propose that both the intense lateral transmission of fungal material within leafcutter nests and the selection of more adapted fungal strains are involved in the homogenization of the symbiotic fungal stock.

A search for markers of sugarcane evolution

Com o propósito de determinar a relaçäo filogenética entre a cana-de-açúcar e membros da subtribo Saccharinae,a regiäo gênica nuclear ITS1-5,8S-ITS2 (ITS: espaçador interno transcrito; 5,8S: DNA ribossomal 5.8S), com alta taxa evolutiva, foi identificada no banco de dados do projeto genoma "Sugarcane Expressed Sequence Tag" (SUCEST). Uma análise através do método de parcimônia, utilizando esta regiäo e seqüências homólogas de 23 Andropogoneae retiradas da base de dados GenBank, indicou que a cana-de-açúcar é o grupo-irmäo de Saccharum sinense. No entanto, devido à pequena quantidade de caracteres informativos para parcimônia e à homoplasia presentes na regiäo ITS1-5,8S-ITS2, näo foi possível determinar com segurança a relaçäo filogenética entre a cana-de-açúcar e alguns dos demais membros da tribo Saccharine. Como alternativa para esta baixa resoluçäo, dezessete regiões gênicas nucleares, cloroplasmáticas ou mitocondriais foram selecionadas a partir do banco de dados SUCEST com o objetivo de encontrar marcadores mais apropriados para a reconstruçäo da filogenia da cana-de-açúcar. Entre elas, aquelas correspondentes à alfa-tubulina, rpl16, a rpoC2 apresentaram baixa incidência de polimorfismo e taxas de evoluçäo equivalentes ou mesmo maiores do que a observada para a regiäo ITS1-5,8S-ITS2. Estes marcadores säo propostos como preferenciais para estudos filogenéticos da subtribo Saccharinae.

Two permanent linear chains of sex chromosomes in Neotermes fulvescens and karyotypes of two other neotropical Kalotermitidae species (Insecta, Isoptera).

Meiosis and (or) mitosis of males and females of Cryptotermes brevis, Eucryptotermes wheeleri, and Neotermes fulvescens, all of them from the neotropical region, were analyzed. Cryptotermes brevis showed a similar karyotype to that obtained by other authors for specimens of the neartic and Australian regions (2n = 36 for females and 2n = 37 for males, with XX and XYY sex mechanisms, respectively). Eucryptotermes wheeleri, the only species that has been described in this genus, showed the lowest number of chromosomes reported for Isoptera (2n = 22) until now. The male meiosis of this species presents a linear chain of six sex chromosomes, three of them being X and three of them Y chromosomes. Neotermes fulvescens showed a diploid number of 40 for males and 42 for females and, in the first male meiosis, two linear chains of chromosomes, both related to sex. One of the chains, named A, presented nine chromosomes and the other, named B, seven chromosomes. Hypotheses to explain these mechanisms are formulated in this paper and putative ancestral relationships with other species of Kalotermitidae are presented.