New species of beetle discovered in the world's deepest cave

This is a drawing of Duvalius abyssimus. Credit: Sinc - José Antonio Peñas

The unusual habitat of the Krubera cave in the Western Caucasus remains a mystery. Researchers from two Spanish universities have discovered a new species of beetle in the depths of this cave.

Cave beetles are one of the most iconic species found in subterranean habitats. They were historically the first living organisms described by science that are adapted to the conditions of hypogean or subterranean life.

Now, a Portuguese scientist and a Spaniard have discovered a new species of beetle in the deepest cave known to man; a cave 2,140 metres deep. It is the Krubera cave, situated in the Arabika massif in the Western Caucasus.

Ana Sofía Reboleira, researcher from the Universities of Aveiro and La Laguna, and Vicente M. Ortuño, from the University of Alcalá, have published their discovery in the scientific journal 'Zootaxa'.

"The new species of cave beetle is called Duvalius abyssimus. We only have two specimens, a male and a female. Although they were captured in the world's deepest cave, they were not found at the deepest point," Ortuño, who has dedicated the last 10 years to studying subterranean fauna, said.

The Duvalius genus is a successful colonizer of Earth's depths. The majority of species have a hypogean lifestyle and live in caves or the superficial underground compartment.

"The new species' characteristics indicate that it is moderately adapted to life underground. Proof of this is that they still have eyes, which are absent in the highly specialised cave species," added the expert.

The Arabika massif region in Abkhazia, where this cave is found, is biogeographically a very interesting area. Altitudes fluctuate between 1,900 and 2,500 metres and the cave is composed of lower and upper Jurassic-Cretaceous limestone.

Its large area has provided endless subterranean refuges for fauna. In fact, various genera of endemic cave beetles live in the Western Caucasus. "Its location is strategic, since there are fauna of European, Asian and also endemic origin in the zone," the scientist underlined.

The entrance to the cave is 2,240 metres above sea level and 15 kilometres from the Black Sea. Below numerous vertically-cutting sections, it reaches a depth of 1,400 metres. From this level, it splits into branches and in order to reach the greatest known depth, it is necessary to pass various flooded underground chambers using diving techniques.

"The discovery of the new beetle provides important data on species that co-exist in these almost unknown ecosystems, even more so when they are found in a geographical area that is very difficult to access, such is the case with this cave," Ortuño concluded.

Source:  FECYT - Spanish Foundation for Science and Technology

Brazilian zoologists discovered the first obligate cave-dwelling flatworm in South America

The type locality of the new cave-dwelling species in northeastern Brazil is shown.
 Credit: Rodrigo Ferreira; CC-BY 4.0

Typical cave-dwelling organisms, unpigmented and eyeless, were discovered in a karst area located in northeastern Brazil. The organisms were assigned to a new genus and species of freshwater flatworm and may constitute an oceanic relict. They represent the first obligate cave-dwelling flatworm in South America. The study was published in the open access journal ZooKeys.

Freshwater flatworms occur on a wide range of habitats, namely streams, lagoons, ponds, among others. Some species also occur in subterranean freshwater environments.

Brazil has more than 11,000 caves, but their species diversity is largely unknown. Field work by Rodrigo Ferreira, from University of Lavras, Brazil, in a karst area located in northeastern Brazil, has found the first obligate cave-dwelling flatworm in South America. Flatworm researchers from University of Vale do Rio dos Sinos (UNISINOS), Brazil, Ana Leal-Zanchet and Stella Souza, described it as a new genus and species.

The new species, which was named Hausera hauseri, is a typical cave-dwelling organism, unpigmented and eyeless. The genus and species names were proposed in honour to a Hungarian biologist, the late Prof. Dr. Josef Hauser, who immigrated to Brazil and studied freshwater flatworms over many years.

The sampling area of the new species is unique in comparison with other karst areas in Brazil. Most Brazilian limestone formations are located in inner portions of the country, which must have prevented marine groups from colonizing these caves in the past. In contrast, this karst area is located near the sea, and its limestone outcrops are at low altitude, which has allowed different invertebrates to colonize the caves during sea level rises in the past. Thus, the new species may constitute an oceanic relict as is the case of other cave-dwelling invertebrates found in this karst area in northeastern Brazil.

Source: Pensoft Publishers