Comparative description of the hairy structures in two endemic Velia species (Insecta: Hemiptera: Heteroptera: Veliidae): V. currens (Fabricius, 1794) and V. gridellii Tamanini, 1947

This study provides the first description, based on SEM imagery, of the hairy structures related to life on the water surface of two Alpine-Apenninic species belonging to the genus Velia: V. currens (Fabricius, 1794) and V. gridellii Tamanini, 1947. In general, no relevant differences in the organization and form of these structures were found between the two species. Similarly, few differences were observed between males and females, and in comparison with the only congeneric with hairy structures thus far described, V. caprai Tamanini, 1947, confirming a substantial homogeneity within the subgenus Plesiovelia. The discovery of a double layer of microtrichia in both our species allowed us to detect them even in V. caprai, for which only a single layer was previously described. Finally, the presence of a structure corresponding to the male grasping comb was discovered in females of V. gridellii and is reported for the first time in the genus and in the Old World Veliinae. A similar structure was not identified in V. currens. This difference may be relevant for better understanding the relationships among species belonging to this genus.