The scientists, on an expedition to Alto Mayo, identified among the 27 new species discovered an amphibious mouse with webbed feet and a blob-headed fish.
Conservationists from non-profit organisation Conservation International and members of local indigenous groups on an expedition to Alto Mayo, including the Amazon rainforest, have detected 27 new species.
Remarkably, up to 48 other new species may have also been found, but the non-profit have said further study will need to be conducted to determine whether they are new.
Trond Larsen, senior director at Conservation International, described the discoveries as “incredible”.
“Discovering so many new species of mammals and vertebrates is really incredible, especially in such a human-influenced landscape,” they said.
Alto Mayo has a relatively high population density, but is a protected area in northern Peru with multiple ecosystems and Indigenous territories.
Yulisa Tuwi, an Awajún woman who assisted with the research, said the report “allows the Awajún to protect our culture, natural resources and our territory”, as it gives them a better understanding of the ecosystems.
“[The Awajún] have extensive traditional knowledge about the forests, animals and plants they live side-by-side with,” Mr Larsen said.
The expedition also found a new species of dwarf squirrel, eight types of fish, three amphibians and 10 types of butterfly.
Despite the “blob-headed” fish deemed a new discovery to science, the Indigenous Awajún people who helped with the expedition were already aware of its existence.
Fish scientists were particularly shocked by its enlarged head, something they had never seen before.
The newly discovered dwarf squirrel measures just 14cm (5.5in), half the length of an average grey squirrel in the UK, which ranges from 24 to 29cm, according to the UK Squirrel Accord.
“[It] fits so easily in the palm of your hand. Adorable and beautiful chestnut-brown colour, very fast,” Larsen said.
“It jumps quickly and hides in the trees.”
Scientists discovered a new species of spiny mouse – named after the especially stiff guard hairs found on their coats, which function similar to the spines of a hedgehog.
They also found a new “amphibious mouse”, which has partially webbed feet and eats aquatic insects.
It belongs to a group of semi-aquatic rodents considered to be among the rarest in the world, with the few species known to exist only spotted a handful of times by scientists.
