A new species group in Megaselia, the lucifrons group, with description of a new species (Diptera, Phoridae).

With 1,400 described species, Megaselia is one of the most species-rich genera in the animal kingdom, and at the same time one of the least studied. An important obstacle to taxonomic progress is the lack of knowledge concerning the phylogenetic structure within the genus. Classification of Megaselia at the level of subgenus is incomplete although Schmitz addressed several groups of species in a series of monographs published from 1956 to 1981. Another problem is the lack of molecular phylogenetic analyses to support morphology-based conclusions. As a contribution towards addressing these problems, we here circumscribe a previously unrecognized monophyletic lineage of Megaselia consisting of species similar to Megaselialucifrons. We base this taxonomic decision on morphological study of an extensive phorid material from Sweden, complemented by molecular analyses of select exemplars using two markers (COI and 28S). We name the clade the lucifrons species group, and show that it contains three distinct species. Our results also demonstrate that Megaseliasubnitida Lundbeck, 1920, previously treated as a synonym of Megaselialucifrons Schmitz, 1918, is a separate species, and we remove it from synonymy. The third species in the group was previously unknown; we describe it here as Megaseliaalbalucifrons sp. n.