Description of a new species of the genus Alagoasa from southern Brazil (CHRYSOMELIDAE, GALERUCINAE, ALTICINI) based on an integrated taxonomic approach

The tribe Alticini (Newman, 1834) is a diverse and amply distributed group of beetles, although its internal arrangement is still poorly defined. The taxonomy of the subtribe Oedionychina is especially challenging, due to mimicry. The present study integrates cytogenetic, morphological, and molecular data to describe Alagoasa neoequestris sp. nov. and establishes its phylogenetic position within the group. The morphological characteristics of the new species are consistent with the genus Alagoasa. The comparison of the male genitalia among the species indicates reproductive isolation. The diploid number and the giant and asynaptic sex chromosomes are typical of the oedionychines, although with considerable differentiation in chromosome morphology and the distribution of the heterochromatin. The location of the rDNA 45S and 5S cistrons is conserved as in Coleoptera. The phylogenetic analysis placed A. neoequestris sp. nov. in Alagoasa, in a cluster with Alagoasa plaumanni, clearly separated from all other genera. The karyotype of the new species contradicts that reported for "Alagoasa equestris” (2n = 12), which coincides with that of the morphologically very similar Omophoita communis. It thus seems likely that “A. equestris” is in fact O. communis. The sum of the evidence supports clearly the description of the new Alagoasa species from southern Brazil.