Deadwood-Dwelling Beetles (Coleoptera: Eucnemidae) in a Beech Reserve: A Case Study from the Czech Republic

The saproxylic beetles (deadwood-dependent) belong to frequently studied groups of forest insects. Eucnemidae is a rare and poorly studied saproxylic family with a hidden life strictly related to deadwood. We studied the family Eucnemidae in a beech reserve, using 59 window traps placed on standing deadwood (snags) and lying logs. A total of 348 specimens in eight species were recorded in two seasons. The identified species included one critically endangered species (CR): Hylis cariniceps; five endangered species (EN): H. olexai, H. foveicollis, Isorhipis melasoides, Eucnemis capucina, and Microrhagus lepidus; one new species found in Bohemia (a region of the Czech Republic): Clypeorhagus clypeatus; and one common species: Melasis buprestoides. Most species preferred lying logs, but E. capucina and M. buprestoides preferred snags. Species richness (q = 0) was higher on lying logs than on snags, and similarly, Shannon diversity (q = 1) was significantly higher on lying logs compared to snags. The species C. clypeorghagus, H. foveicollis, H. cariniceps, and M. lepides preferred moist lying logs, while M. buprestoides and E. capucina preferred drier snags with cavities. The results suggest that in beech forests, lying logs serve as a fundamental habitat for the existence of Eucnemids. This could be due to the more stable microclimatic conditions inside the lying deadwood. From this perspective, our study may help better understand the biology of hidden and understudied rare saproxylic Eucnemids.