Comparative physical mapping of 18S rDNA in the karyotypes of six leafcutter ant species of the genera Atta and Acromyrmex (Formicidae: Myrmicinae).

Leafcutter ants of the Atta and Acromyrmex genera are important plagues in different cultures. Cytogenetic data on chromosome number, morphology, and chromosomal banding pattern are only available for 17 species of leafcutter ants. Molecular cytogenetic data for the detection of ribosomal genes by the FISH technique are scarce, and only 15 Neotropical ant species have been studied.

Cytogenetic studies on populations of Camponotus rufipes (Fabricius, 1775) and Camponotus renggeri Emery, 1894 (Formicidae: Formicinae).

Two valid ant species, Camponotus rufipes and Camponotus renggeri, have recently been the subject of a broad discussion with reference to taxa synonymization. Both species are quite common among the Neotropical myrmecofauna and share some unique traits, such as the shape of the scape and the pilosity patterns of the tibiae and scapes. A single morphological trait can help distinguish these species; however, only a combination of different approaches can enlighten our view of the complex phylogenetic relationships prevailing in the different populations of these two taxa.

Cytogenetic data on six leafcutter ants of the genus Acromyrmex Mayr, 1865 (Hymenoptera, Formicidae, Myrmicinae): insights into chromosome evolution and taxonomic implications.

Cytogenetic data for the genus Acromyrmex Mayr, 1865 are available, to date, for a few species from Brazil and Uruguay, which have uniform chromosome numbers (2n = 38). The recent cytogenetic data of Acromyrmex striatus (Roger, 1863), including its banding patterns, showed a distinct karyotype (2n = 22), similar to earlier studied Atta Fabricius, 1804 species. Karyological data are still scarce for the leafcutter ants and many gaps are still present for a proper understanding of this group.

New sex-determination system in the genus Panstrongylus (Hemiptera: Reduviidae) revealed by chromosomal analysis of Panstrongylus lutzi.

Background: Panstrongylus lutzi (Neiva & Pinto, 1923) is a triatomine species native to Caatinga habitats in north-eastern Brazil. It is considered an important vector of Chagas disease in this region, presenting high rates of natural infection with Trypanosoma cruzi Chagas, 1909, and readily invading houses by flight. This study describes a previously unknown chromosomal sex system in the genus Panstrongylus based on P.

Cytogenetic data on the threatened leafcutter ant Atta robusta Borgmeier, 1939 (Formicidae: Myrmicinae: Attini).

The karyotype of the threatened ant species Atta robusta is described so as to establish the evolutionary relationships of this taxon with other leafcutter ants. Standard Giemsa staining, C-banding, NOR banding, fluorochromes CMA3/DAPI, Hsc-FA technique and Fluorescence in situ Hybridization (FISH) using 18S rDNA probe were conducted on a population from Aracruz, state of Espírito Santo, Brazil, allowing for comparisons with data available on Atta and other fungus-growing ant species. The diploid chromosome number observed for A.

The first cytogenetic data on Strumigenys louisianae Roger, 1863 (Formicidae: Myrmicinae: Dacetini): the lowest chromosome number in the Hymenoptera of the neotropical region.

In the present study, the first cytogenetic data was obtained for the ant species Strumigenys louisianae, from a genus possessing no previous cytogenetic data for the Neotropical region. The chromosome number observed was 2n = 4, all possessing metacentric morphology. Blocks rich in GC base pairs were observed in the interstitial region of the short arm of the largest chromosome pair, which may indicate that this region corresponds to the NORs.

Cytogenetics of Melitoma segmentaria (Fabricius, 1804) (Hymenoptera, Apidae) reveals differences in the characteristics of heterochromatin in bees.

To date, more than 65 species of Brazilian bees (of the superfamily Apoidea) have been cytogenetically studied, but only a few solitary species have been analyzed. One example is the genus Melitoma Lepeletier & Serville, 1828, for which there is no report in the literature with regard to cytogenetic studies. The objective of the present study is to analyze the chromosome number and morphology of the species Melitoma segmentaria (Fabricius, 1804), as well as to determine the pattern of heterochromatin distribution and identify the adenine-thymine (AT)- and guanine-cytosine (GC)-rich regions.

The role of fusion in ant chromosome evolution: insights from cytogenetic analysis using a molecular phylogenetic approach in the genus mycetophylax.

Among insect taxa, ants exhibit one of the most variable chromosome numbers ranging from n = 1 to n = 60. This high karyotype diversity is suggested to be correlated to ants diversification. The karyotype evolution of ants is usually understood in terms of Robertsonian rearrangements towards an increase in chromosome numbers.

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.

First cytogenetic characterization of a species of the arboreal ant genus Azteca Forel, 1978 (Dolichoderinae, Formicidae).

In this paper we present, for the first time, a detailed karyotype characterization of a species of the genus Azteca (Dolichoderinae, Formicidae). Cerebral ganglia from Azteca trigona Emery, 1893 were excised and submitted to colchicine hypotonic solution and chromosomal preparations were analyzed through conventional staining with Giemsa, C-banding, silver nitrate staining (AgNO3) and sequential base-specific fluorochromes. The analysis shows that Azteca trigona has a diploid number of 28 chromosomes.

Occurrence of B chromosomes in Tetragonisca Latreille, 1811 (Hymenoptera, Apidae, Meliponini): A new contribution to the cytotaxonomy of the genus.

Tetragonisca angustula and Tetragonisca fiebrigi have recently been listed as valid species. This study aimed to cytogenetically investigate both species, emphasizing the new registry of B chromosomes in the tribe Meliponini. We analyzed colonies of T.

Karyotypic description of the stingless bee Oxytrigona cf. flaveola (Hymenoptera, Apidae, Meliponina) of a colony from Tangará da Serra, Mato Grosso State, Brazil.

The aim was to broaden knowledge on the cytogenetics of the subtribe Meliponina, by furnishing cytogenetic data as a contribution to the characterization of bees from the genus Oxytrigona. Individuals of the species Oxytrigona cf. flaveola, members of a colony from Tangará da Serra, Mato Grosso State, Brazil, were studied.

Cytogenetic characterization of Partamona cupira (Hymenoptera, Apidae) by fluorochromes.

Four colonies of the stingless bee Partamona cupira (Hymenoptera: Apidae) were cytogenetically analyzed using conventional staining and the fluorochromes CMA(3) e DAPI. The females have 2n = 34 chromosomes (2K = 32 M¯+2 A¯). Some females, however, presented an additional large B acrocentric chromosome, to a total of 2n = 35.

DNA characterization and karyotypic evolution in the bee genus Melipona (Hymenoptera, Meliponini).

We analyzed patterns of heterochromatic bands in the Neotropical stingless bee genus Melipona (Hymenoptera, Meliponini). Group I species (Melipona bicolor bicolor, Melipona quadrifasciata, Melipona asilvae, Melipona marginata, Melipona subnitida) were characterized by low heterochromatic content. Group II species (Melipona capixaba, Melipona compressipes, Melipona crinita, Melipona seminigra fuscopilosa e Melipona scutellaris) had high heterochromatic content.