Antarctic midges
Like none has ever seen

Despite the slow rise of antarctic vertebrates, the most abundant and biodiverse animal group always remains the insect class, with hundreds of native species that evolved from the already present species or derived from recent South American clades' dispersions, rarely from the Oceanian one. Diptera are surely the most interesting group: since lots of species were present in the holocenic period, they had enough time to speciate in several lineages, adapting to different and unexpected niches. Many flies and mosquitos adapted to live in antarctic rivers: some of them have developed a sort of internal gills that work differently from other gilled insects like mayflies, dragonflies, and caddisflies. Water is inflated from various modified abdominal pores, the same that were originally used on land to breathe air. Even if evolutionary amazing, the most unique adaptation of this successful group of insects happened in a land species, that become pedomorphic, retaining juvenile tracts in adulthood: the wormflies (Vermidipteridae). At first impact, a wormfly looks like a bizarre worm, with an insect-like head in adulthood that looks more like the one of a ground beetle than a fly. They occupy a similar niche to earthworms, which are poorly diversified in Antarctica, being detritivorous and living in the first substrate of the ground (the hummus). Thanks to its primordial ancestor (very likely the holocenic Antarctic midge), wormflies possess hemoglobin, that transports more efficiently oxygen in their body, a surely helpful adaptation for an insect that live often in anoxic environments.