Distribution range

Despite the fact that representatives of this genus have been known for more than a century, it was only in 2016, when they were recognised as separate and independent genus of subterranean beetles, using both molecular and classical morphological methods. Until then, they were treated as a part of the largest beetle genus in the Southeastern Dinarides, Anthroherpon.

Six species of Graciliella look very similar to the slenderneck beetle (genus Leptodirus), living in Northwestern Dinarides. They have a long and narrow “neck” (1st segment of the prosoma), and rounded abdomens – due to the inflated elitrae (hardened forewings). The most likely cause of close morphological similarity between the two genera is the similarity of their habitats.

The phenomenon of unrelated organisms looking alike, behaving similarly or having similar physiological adaptations is called convergence or parallel evolution. Convergences are common in extreme environments like deserts, permanently frozen areas or deep sea habitats – and in the subterranean world.

It is interesting to note that both genera mentioned above are marked by the most extreme morphology within the round fungus beetles family (Leiodidae). While the soil-dwelling half rounded beetles, ancestors of round fungus beetles, are only a few mm large, the representatives of both cave-dwelling genera reach up to 9 mm – and are among the largest subterranean beetles in the Dinarides.