Caracterização molecular e relações filogenéticas de Diplotriaena bargusinica Skrjabin, 1917 (Nematoda Diplotriaenidae)

Abstract

The nematode taxonomy is based mainly on the morphological and morphometric features. They are among the most difficult pests to be identified due to the small size of some species and/or difficulties in observing essential character for diagnosis by conventional optical microscopy. Diplotriaena bargusinica is a parasite of birds whose identification is based strongly on morphological characteristics. The morphology of the specimens used in this study has raised questions about the specific identification, due to variations in shape in the spicules of males. The increasing knowledge of the variability of genetic information has encouraged the use of DNA markers, in combination with morphological data for inferring phylogenetic relationships among different taxa. The organization of rDNA genes make them appropriate targets for DNA amplification by PCR, allowing genetic studies aimed at identifying nematodes. In view of the importance of taxonomy with the potential of molecular biology, this study aims to confirm the morphological identification of D. bargusinica and establish phylogenetic relationships among the parasites of Spirurida order. Twenty partial sequences of the 18S region of nuclear rDNA from D. bargusinica were generated by DNA sequencing, these being the first genetic data for the species. Based on the analysis of the genetic distance matrix was observed little difference between the genetic sequences, with only three showed variable sites. Phylogenetic trees were obtained by the methods: Neighbor-Joining, Minimum Evolution and Maximum Likelihood. Both had very similar topology, showing that the clades are monophyletic origin and corroborated phylogenetic analysis based on the traditional taxonomy. In this study, the molecular and morphological data correlated were crucial to elucidate the group's taxonomy.