Phylogeny of sibling species of Simulium venustrum and S. verecundum (Diptera: Simuliidae) based on sequences of the mitochondrial 16S rRNA gene

The phylogeny of four sibling species of Simulium venustum (CC, CC3, CC4, and AC(gB)) and two sibling species of S. verecundum (AA and ACD = S. rostratum) was reconstructed using nucleotide sequences of the mitochondrial large subunit rRNA gene. Separate phylogenetic analyses were performed by dividing the sequence data into: (1) helices of a computer-generated secondary structure of the rDNA; (2) loops of the computer-generated structure; (3) helices of a consensus secondary structure (deduced by comparing the computer-generated structure of black flies with the corresponding structures proposed for the fruit fly (Drosophila yakuba) and the mosquito (Aedes albopictus)); (4) loops of the consensus structure; (5) both helices and loops of the consensus secondary structure; and (6) the entire sequence regardless of secondary structure, including 11 variable sites in regions where the prediction of secondary structure was not possible. We found that different data sets led to different phylogenetic conclusions. The phylogenies based on data sets 4 and 6 were consistent with nonmolecular evidence, while the phylogenies based on other data sets were not. Our study suggests S. decorum, a morphospecies, might have shared a common ancestor with sibling species of S. venustum.