Estudo citogenético e molecular em espécies do gênero Omophoita Chevrolat, 1836 e Alagoasa Bechyné, 1955 (Chrysomelidae, Alticinae) com descrição de uma nova espécie.

Abstract

The Coleoptera order represents 40% of the described insects and includes the subfamily Alticinae, which has a complex taxonomic hierarchy and many cases of mimicry which makes this categorization more difficult. The subtribe Oedionychina has been studied with a cytogenetic approach due its peculiar characteristics about the giant and asynaptic sex chromosomes. The eukaryotic genome consists of heterochromatin that contains various types of repetitive DNA and have an important in its structure and activity, and chromosomal evolution. Chromosome Painting is a technique that uses probes produced by DOP-PCR, and is used to highlight rearrangements and homeologies of species, but it can also map repetitive DNA. The aim of this work was to describe the new specie A. neoequestris, using cytogenetic, morphological and molecular studies, including phylogenetic analysis with similar species, given it a scientific name, and map repetitive DNAs obtained by DOP-PCR and mapped by the technique of Chromosome Painting in Omophoita communis. The specie Alagoasa neoequestris has morphological features that validate its taxonomic position within the genus. Other species of the genus did not have the elytral pattern found. Comparison of the male genitalia with other species of the genus showed differences that suggest reproductive isolation. The chromosomal number 2n=22 and Xy sex determination system with giant and asynaptic sex chromosomes is representative of the subtribe. The variation in chromosomal morphology found and the location of constitutive heterochromatin in three bivalents are associated with karyotype differentiation of the genus. The 45S and 5S rDNA cístrons, colocalized in one autosomal pair is considered ancestral for Coleoptera. Phylogenetic analysis grouped A. neoequestris within the genus Alagoasa, in a branch with Alagoasa plaumanni, and separated from O. communis and O. equestris. In the literature, are individuals identified as "Alagoasa equestris" with chromosome number 2n=12 morphologically similar to Omophoita communis and Omophoita equestris. The results obtained in this study disagree with those described in the literature for "A. equestris" described as 2n=12. This chromosomal number of "A. equestris" is equal to the number described for O. communis and suggests that "A. equestris" may have been confused with O. communis during that study. Based on this and in the analysis of the phylogenetic relationship, the species studied in this paper is a new specie of the genus in southern Brazil, supported by integrated taxonomy. The hybridization of the probe in O. communis showed centromeric markings in all autosomes and in the pericentromeric region of the X sex chromosome and intersticial of y chromosome. These markings correspond to the location of C-banded heterochromatin in Coleoptera and also in Oedionychina. The use of 30 µg competitor, standard for chromosome painting, inhibited all hybridizations confirming that the probe contains repetitive sequences. Possibly these sequences in the genome were mostly amplified by DOPPCR, as has also been observed in other work with Chromosome Painting. Nevertheless, further studies are still needed with techniques that complement the results of characterization repetitive DNA in O. communis.