I.G. Bagnjuck, Biological Research Institute of St. Petersburg University, St. Petersburg, Old Petergof, 198904 Russia
S.I. Sukhareva, Biological Research Institute, St.Petersburg State University, Old Peterhof 198904, Russia
V.G. Shevchenko, Biological Research Institute of St. Petersburg University, St. Petersburg, Old Petergof, 198904 Russia
At present, the genus Trisetacus (the largest one in the family Nalepel-lidae) includes 45 species. The representatives of this family connected with coniferous plants have many conservative features (three setae on the dorsal shield, subdorsal setae and tibial spur).
An analysis was made of 25 morphological features of 37 species. All data were processed using the correlation and factor analysis. The morphological changes in the species of this genus are connected with their phylogenetic relationship and the distribution of the coniferous host plants. A survey of the data on the evolution of conifers allow one to trace the formation and the evolution of the genus Trisetacus on the conifers of the northern hemisphere.