Saturday 23 November 2019

Leptodirus hochenwartii - endemic cave beetle

Slovenian caves are amazing places to go searching for rare wildlife, regardless of the season and the outside weather conditions. Caves have a constant air temperature throughout the year, a high air humidity and are dominated by complete darkness. Life in the underground goes on following its own rhythm since millenia and animals living here are specifically adapted to a slow and sight-less existance. Most cave animals are very small (mostly invertebrates) and are usually also difficult to see. 
There are more than 10.000 known caves in Slovenia, mostly in the central and western part of the country, lying on limestone. The Karst, where we live is absolutely full of caves and our fortune is to be able to explore them and find very rare animals not far from home.
Today the weather was cloudy and wet, thus ideal to escape from the surface's late-autumn mood and explore a cave in search of rare beetles.
Entering the cave...
Inside the cave.
Small pools of water - ideal places to find cave animals.
The first stage of a stalactite.
Odd rock formations.

Our main target was the rare and bizzare Narrow-necked Cave Beetle Leptodirus hochenwartii, the first described cave beetle in the world. It was first found in 1831 in the famous Postojna cave by Luka Čeč, a local cave guide who actually discovered the inner parts of the same cave about a decade earlier. More detailed info about the discovery of Leptodirus hochenwartii can be found in this excellent article.
The discovery of this amazing beetle triggered the active search for other cave animals and later the development of speleobiology. There are now 400-450 known species of cave animals in the Slovenian Karst and Slovenia is known worldwide as the cradle of speleobiology.
The Narrow-necked Cave Beetle is a true troglobite, meaning it can only live in cave ecosystems and nowhere else. Because of complete darkness inside caves, the beetle has no eyes and relies on other senses. The specie's most characteristic features are the long "neck" (actually the thorax) and the swollen abdomen. It is endemic to the Dinaric Karst, being only found in parts of southwestern Slovenia, Croatia and the Trieste Karst in Italy.
Finding one inside a large cave is not an easy task as the beetle is roughly the size of a large ant! We were thus very relieved to find one, walking a cave wall, some 3 meters above the ground. Thanks to a good zoom, we managed some documentative shots of this rare animal.
Spot the beetle...
Narrow-necked Cave Beetle Leptodirus hochenwartii

Other animals were to be found in the cave, the most obvious being some hibernating Lesser Horshoe Bats Rhinolophus hipposideros. The cracks and crevices within the cave walls were hosting the two rather common species of cave Orthoptera: Cave Cricket Troglophilus cavicola and Neglected Cave Cricket Troglophilus neglectus. Another interesting and rather typical cave animal was the pigment-less Cave Woodlouse Titanethes albus. On the other hand, we didn't find any of the cave spiders, which are also typical for this enviroment and are completely blind.
Lesser Horshoe Bat Rhinolophus hipposideros
Cave Cricket Troglophilus cavicola
Neglected Cave Cricket Troglophilus neglectus
Cave Woodlouse Titanethes albus
Bone of a presumed cave animal (bear??).
Old inscription by an early cave explorer, dating back to 1863.

For more about the subject check the following links:
The underground world - on our WildSlovenia website
Karst Museum in Postojna