Chronicles of another alien

While borax have not achieved high diversification due to limitations in size and diet, rompos have fared better.
Today, these bizarre lagomorphs that reached Antarctica trough an ice bridge comprise about fifteen species exist, adapted to nearly every Antarctic environment, including four insular species in the Sparso Archipelago. Their distribution, however, is not homogeneous: rompo's biodiversity hotspots are found in colder climates, like temperate lowland forests and mountainous regions in warmer areas. Their size variation is as great as the one of stottmice, with some species slightly smaller than their roe deer-sized ancestors, and others already exceeding 300 kg. Some of these have adopted a scansorial lifestyle, using trees as a way to escape from predators. Others are slowly moving in rivers and lakes, as a way to survive the hot summers of the northern latitudes. Some others have decided instead to become true bulldozers, trampling trees as nothing, like the treechopper (Lagosilva semibipedis).
The treechopper mostly inhabits the southern plateau of the continent, where austral forests and shrub tundra prevail, with some smaller populations found northern in some mountainous areas like the Transantarctic mountains, the Central Massif, and the Peninsular Alps.
Primarily browsers, they feed on leaves during the warm season and switch to bark and harder plant matter in colder months. After 5 million years of natural selection, the species has developed a graviportal structure, including a return to a more plantigrade locomotion. Adaptations in the hips allow the treechopper to spend extended time on two legs, an advantage when feeding on taller vegetation. Thanks to their large and robust teeth, trechoppers (as th name suggest), can cut down trees like a beaver, in order to feed on the soft vegetation of the top. This behaviour create meadows inside closed forests that increase biodiversity, making them important keystone species.

Highly social, treechoppers form herds of 30-90 individuals, led by an older, dominant female who serves as matriarch. Males, which are slightly larger in size, form smaller male herds of 4-10 individuals, which stay separate from female ones until the breeding season.Thanks to their size and herd protection, matriarchs can live up to 40 years, an astonishing lifespan for a lagomorph and a herbivorous mammal in general, which rarely exceed 20 years. Their longevity is also supported by a low metabolic rate, which slows cellular aging and reduce the risk of cancers. Because of the low metabolic rate, sexual maturity is reached late compared to other herbivores of similar size, at around 5 years of life.

Although the initial "ecological clash" with stottmice over resources, rompos have now established their own ecological niches, particularly due to their ability to feed on tough plant matter, something stottmice seldom exploit, and the presence of functional claws to grab and climb.
Like borax, the future of rompos looks bright. Their antarctic chronicle has just started.