Morphological diversity of the skeletal structures of fleas (Siphonaptera). Part 4: The general characteristic and features of the abdomen

Abstract

Characters of 25 abdominal structures were analyzed in the fleas of 96 genera representing over 90% of the world fauna. It was shown that different flea taxa could be described based on 16 universal and 12 specific characters, whose 108 states reflect the entire known diversity of the flea abdominal morphology. Of them, 16 characters with 39 states are formulated based on universal terms. Five universal characters with 13 states describe the proportions of various structures, and also the proportions and shapes of their sclerites; 17 specific characters with 69 states describe the structure of the skeletal elements and the patterns of their junctions. Judging by the number of characters (14) and their states (69), the most evolutionarily flexible structures in fleas are the inner sclerites and anchoring structures of the aedeagus, sternite IX in males, and also the spermatheca and tergite I in females. The character states reflecting the possible phylogenetic closeness of taxa comprise 39%, while 61% of the abdominal character states are homoplasies.