One, two, three stottmice

Like many Antarctic animals, stottmice reached their biodiversity peak around 80 million years ago, only to experience a sudden collapse following the Continental Crisis. Today, just one species remains: the triple stottmouse (Rangifermus relictus), which retains a similar size to its ancestor, the dwarf stottmouse. Its resilience and adaptability have enabled these seemingly fragile creatures to thrive, making them the one of the most widespread herbivore on the continent—though not the most numerous, a title held by the muskox tramplerat. Their slender yet agile bodies make them the fastest animals in the region, with few predators possessing the endurance to chase them across open landscapes.

The name "triple stottmouse" comes from the species' structure, divided into three genetically and ecologically distinct subspecies, each adapted to different habitats and diets. Here's a breakdown of the three:

• Follia Plateau Subspecies (R. relictus occidentalis)
  This is the most abundant and widespread subspecies, thriving in the vast grasslands of the Follia Plateau. In this open environment, herbaceous plants dominate their diet, and they have evolved longer limbs on average to cope with a higher risk of predation. Collared pinpiercers are their main predators, with carnieri, ottofoxes and banchisaraptors often preying on the juveniles. 

• Shrubland Subspecies (R. relictus centralis)
  Found in the northernmost parts of the Peninsula, particularly in Neve Delta, the Seamount, and some Pacific Rim islands, this subspecies inhabits shrubby, often rugged terrain. With shorter limbs for navigating uneven landscapes, they are highly agile, capable of swift directional changes—an adaptation crucial for survival. Their diet is largely foliage-based (up to 70% locally), thanks to the abundance of shrubs in their environment. This subspecies undertakes remarkable seasonal migrations, wintering in the Pacific Rim islands after crossing sea ice in colder months.

• Hard Tundra Subspecies (R. relictus orientalis)
  The rarest of the three, this subspecies inhabits the moss tundras of Greenrock, a harsh and nutrient-poor environment. Smaller than the others due to their limited diet of mosses (30% smaller on average), they have broader, sturdier feet to move across frozen, rocky terrain without slipping. Due to the remoteness of their habitat, they face fewer predators, with carnivore and pinpiercer populations so sparse that predation pressure is almost nonexistent. As a result, this subspecies is the most docile, yet the more adapted to live in these inhospitable territories. Mosses and lichens are the main and almost the only available food source for this stottmouse.

The three subspecies evolved before, not after, the Continental Crisis, during a time when geographic isolation allowed for greater differentiation in their forms and behaviors. In another scenario, this process would have led to the emergence of three distinct species. However, the rapid cooling event of the Crisis halted this divergence. While increased interbreeding among the subspecies reduces the risk of genetic bottlenecks, the resulting hybrids often have suboptimal adaptations for any specific habitat.
Like many other species in Antarctica, the future of stottmice is uncertain and full of pitfalls. None is spared by the grip of the cold.