The strange big-eared brown bat was first described in Brazil in 1916 and has not been seen since, but has now been rediscovered by a research team. Captured in the Palmas Prairie Wildlife Reserve in 2018, the bat was identified as a rare species, revealing its presence in different terrains and altitudes, although its conservation status is still classified as data deficient due to threats to its habitat.
The strange big-eared brown bat (Histiotus alienus) was first described by the scientific community in 1916, by the British zoologist Oldfield Thomas. This description comes from a specimen found in Joinville, Paraná state in southern Brazil.
No captures of the species have been reported for more than a century. It can only be identified by its master type, a unique specimen that represents the physical and molecular characteristics of the species and is housed at the Natural History Museum in London, England. Today, a century later, the species was rediscovered.
Scientists Dr. Vinícius C. Cláudio, Ms. Brunna Almeida, Dr. Roberto L.M. Novaes and Dr. Ricardo Moratelli of the Osvaldo Cruz Foundation of Brazil, as well as Dr. Liliani M. Tiepolo and Ms. M.M.M. Miepolo. Dr. Liliani M. Tiepolo and Ms. Marcos A. Navarro of the Federal University of Paraná in Brazil published a paper in the open access journal "ZooKeys" detailing the sighting.
In 2018, during a field trip for the research project Promasto (Mammals of Campos Gerais National Park and Palmas Steppe Wildlife Reserve), researchers captured a specimen of a big-eared bat in the Palmas Steppe Wildlife Reserve. To catch it, they used mist nets - equipment used when catching bats and birds - set up on the edge of a forest. When they compared it to the tropical big-eared brown bat (Histiotus velatus), which is commonly caught in the area, they found it looked nothing like it.
The unidentified big-eared bat specimen was subsequently collected and deposited at the National Museum in Rio de Janeiro, Brazil, for further study.
After comparing the puzzling specimen to hundreds of other big-eared brown bats from nearly every species in the genus, the researchers ultimately identified the bat as the strange big-eared brown bat and confirmed its second known record. "Since descriptions of several species in this genus are over a hundred years old and somewhat obscure, the comparisons and data we provide will help in the correct identification of the big-eared brown bat," they said.
The ears of the peculiar big-eared brown bat are oval, enlarged and connected by a very low membrane; the back and abdominal hair are dark brown; the total length is about 100 to 120 mm. This combination of features is most similar to the southern big-eared brown bat (Histiotus magellanicus), which has virtually no membrane connecting its ears.
To date, the only known record of the strange big-eared brown bat comes from Joinville in the southern Brazilian state of Santa Catarina, about 280 kilometers from where it was discovered in 2018. To date, the species is known to occur in a variety of terrains ranging from dense tropical rainforests to arrow bamboo forests, riparian forests and grasslands, and at altitudes ranging from sea level to over 1,200 meters above sea level.
However, the expansion of the species' range does not represent an improvement in its conservation status: the species is currently listed as data deficient by the International Union for Conservation of Nature. Its habitat, the highly fragmented Atlantic Forest, is currently under pressure from agricultural activity.
But hope remains: "The new record of H. alienus in Palmas is within a protected area, suggesting that at least one population of this species may be protected," the researchers wrote in the study.