Two Spanish scientists have discovered a new species of beetle, which they have called Oromia thoracica. This blind weevil is brownish-grey and has a flattened body and thorax that almost covers its head, an adaptation to its life underground. It is described in the journal Zootaxa.
In recent years, the underground environment of the Canary Islands has revealed many of its best guarded secrets. Spiders, millipedes, psuedoscorpions, cockroaches, and beetles have emerged mainly from the depths of the Agaete valley, on the northwest part of Gran Canaria. This area has some of the oldest soil on the island originating from the Miocene epoch, between 23 and 5 million years ago.
The new species of weevil was found in the subsoil in a small area of the valley, a site which relatively recently bore witness to a volcanic eruption.
“The first specimen of Oromia thoracica was not caught until six years after the start of the study, and we had to wait another four years before another five known specimens fell into the traps,” said Heriberto López, one of the co-authors. López is convinced that the underground world has more big surprises in store in terms of biodiversity discoveries on the Canary Islands.
The new beetle is less than five millimeters long, but it is larger than other species of the same genus that are native to the Canary Islands. According to its finders, the morphological characteristics of this beetle are unmistakeable when classifying it as an underground species: it is blind and has a reddish-brown color that is typical of subsoil insects.
“Its extremities are a little longer and flatter, and its body is flattened, which indicates a greater degree of adaptation to the underground environment or life in very narrow cracks,” said Antonio Machado, the other co-author.
The most striking part is the pronotum, which extends over the head as a kind of heart-shaped shield, almost completely covering it, unlike other species of its group.
“The surface of this new species’ pronotum is quite smooth, in contrast to the rest of the species of Oromia which appear sculpted or even have very noticeable keel structures,” according to the researchers.
Because it lives deeper down in the subsoil, out of the action scope of the traps, the beetle took a while to appear. However, the authors linked the appearance of this species to the presence of dying bushes nearby.
“The rotting roots of the bushes must strongly attract underground species which feed off this type of food source, as is the case of Oromia thoracica,” said López.
The Oromia genus is also relatively recent. It was discovered in 1987 as a result of explorations and studies of the underground environment on the Canary Islands starting in the 1980s. A new species is discovered every six days on these islands. However, this rate is decreasing due to the knowledge that now exists on its flora and fauna.
In the case of Gran Canaria, the underground environment is still a great mystery, and scientists consider it to be a real hotspot for underground biodiversity.
“There is still much to discover on the island’s biodiversity, and at the moment it is being revealed as one of the environments where more new species are waiting to be discovered on Gran Canaria,” the authors said.
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