The Lukina Jama-Trojama is the deepest cave system in Croatia, extraordinary for its vertical shape, long pits and great depth of -1392 m. From an ecological point of view this cave system is extremely interesting for having three microclimatic layers: first an entrance icy part with temperatures of about 1 °C followed by a middle part with temperatures up to 2 °C. The bottom part of the system shows higher temperatures up to 4 °C. These unusual living conditions make the cave extremely interesting for biodiversity research.
Now my colleague and friend Alexander Weigand has described a new species of the genus Zospeum from this cave system. The new species Zospeum tholussum is a small and fragile snail (1-2 mm), with a dome-like shaped translucent shell. Only one living specimen was found during an expedition around the galleries of the cave system. The animal was found at the remarkable depth of 980 m, in an unnamed chamber full of rocks and sand with a small stream running through it.
The species is related to Zospeum amoenum, but can be distinguished from the latter by some shell features and - as shown in the study as well - by DNA Barcoding.
All known species from the cave-dwelling genus Zospeum have only limited ability to move. Their preference for muddy habitats and the fact that they are usually located near the drainage system of the cave, in a close proximity to running water, however suggest that these animals are not exactly immobile. Scientists hypothesize that dispersal is achieved through passive transportation via water or larger mammals.