Résumé
The genus Stomoxys Geoffroy (Diptera; Muscidae) contains species of
parasitic flies that are of medical and economic importance. We conducted
a phylogenetic analysis including 10 representative species of the genus
including multiple exemplars, together with the closely related genera
Prostomoxys Zumpt, Haematobosca Bezzi, and Haematobia Lepeletier &
Serville. Phylogenetic relationships were inferred using maximum
likelihood and Bayesian methods from DNA fragments from the cytochrome c
oxidase subunit I (COI, 753 bp) and cytochrome b (CytB, 587 bp)
mitochondrial genes, and the nuclear ribosomal internal transcribed spacer
2 (ITS2, 426 bp). The combination of mitochondrial and nuclear data
strongly supports the paraphyly of the genus Stomoxys because of the
inclusion of Prostomoxys saegerae Zumpt. This unexpected result suggests
that Prostomoxys should be renamed into Stomoxys. Also, the deep molecular
divergence observed between the subspecies Stomoxys niger niger Macquart
and S. niger bilineatus Grünbreg led us to propose that they should rather
be considered as distinct species, in agreement with ecological data.
Bayesian phylogenetic analyses support three distinct lineages within the
genus Stomoxys with a strong biogeographical component. The first lineage
consists solely of the divergent Asian species S. indicus Picard which
appears as the sister-group to all remaining Stomoxys species. The second
clade groups the strictly African species Stomoxys inornatus Grünbreg,
Stomoxys transvittatus Villeneuve, Stomoxys omega Newstead, and Stomoxys
pallidus Roubaud. Finally, the third clade includes both African occurring
and more widespread species such as the livestock pest Stomoxys calcitrans
Linnaeus. Divergence time estimates indicate that the genus Stomoxys
originated in the late Oligocene around 30 million years ago, with the
major lineages diversifying in the Early Miocene between 20 and 15 million
years ago at a time when temperate forests developed in the Northern
Hemisphere.