Unrecognized for centuries: distribution and sexual caste descriptions of the West European Aphaenogaster species of the subterranea group (Hymenoptera, Formicidae).

There are only two Aphaenogaster species from the subterranea group in the western Mediterranean: A.ichnusa Santschi, 1925, from south-western Europe, and A.subterranea (Latreille, 1798), also occurring in central and eastern Europe. Historically, the two species have been widely misunderstood: A.ichnusa was long considered a Sardinian endemic subspecies of A.subterranea, while its continental populations were misidentified as A.subterranea s. str. Recently, A.ichnusa was elevated to species rank and its worker caste was redescribed with that of A.subterranea, allowing for their correct identification. Yet their distribution was documented in detail only for France and Sardinia. Furthermore, no morphological characters were described to distinguish the males and queens of the two species. By investigating private and museum collections, 276 new records of A.ichnusa are provided here and 154 of A.subterranea from the western Mediterranean. Additionally, qualitative and quantitative morphological characters were combined to identify their males and queens. We present the new southernmost, easternmost, and westernmost distribution limits for A.ichnusa. Based on our results, this species is widely distributed in Italy and Catalonia (Spain), also occurring on several Mediterranean islands, avoiding areas with continental climate and high altitudes. Sicily is the only island to host the less thermophilous A.subterranea, which otherwise extends westward to Galicia (Spain). Sympatric occurrence is not rare along the contact zone. Additional natural history observations are reported regarding foraging habits, associated myrmecophiles, habitat preferences, and colony structure in the two species.

Is it an ant or a butterfly? Convergent evolution in the mitochondrial gene order of Hymenoptera and Lepidoptera.

Insect mitochondrial genomes (mtDNA) are usually double helical and circular molecules containing 37 genes that are encoded on both strands. The arrangement of the genes is not constant for all species, and produces distinct gene orders (GOs) that have proven to be diagnostic in defining clades at different taxonomic levels. In general, it is believed that distinct taxa have a very low chance of sharing identically arranged GOs. However, examples of identical, homoplastic local rearrangements occurring in distinct taxa do exist. In this study, we sequenced the complete mtDNAs of the ants Formica fusca and Myrmica scabrinodis (Formicidae, Hymenoptera) and compared their GOs with those of other Insecta. The GO of F. fusca was found to be identical to the GO of Dytrisia (the largest clade of Lepidoptera). This finding is the first documented case of an identical GO shared by distinct groups of Insecta, and it is the oldest known event of GO convergent evolution in animals. Both Hymenoptera and Lepidoptera acquired this GO early in their evolution. Using a phylogenetic approach combined with new bioinformatic tools, the chronological order of the evolutionary events that produced the diversity of the hymenopteran GOs was determined. Additionally, new local homoplastic rearrangements shared by distinct groups of insects were identified. Our study showed that local and global homoplasies affecting the insect GOs are more widespread than previously thought. Homoplastic GOs can still be useful for characterizing the various clades, provided that they are appropriately considered in a phylogenetic and taxonomic context.