MORPHOLOGICAL DIVERSITY OF THE FLEAS'' SKELETAL STRUCTURES (SIPHONAPTERA). PART 1: GENERAL CHARACTERISTIC AND THE FEATURES OF THE HEAD
Analysis of a considerable amount of data on the anatomy of 14 structures of the head capsule in 96 genera of fleas (over 90 % of the Siphonaptera genera) has shown that different flea taxa can be described based on 32 <i>universal</i> and <i>specific</i> characters, whose 135 states reflect all known diversity of the flea head morphology. 17 characters can be formulated based on <i>universal</i> terms applicable to any structure. Elementary characters can reflect phylogenetic affinity only in association with <i>specific</i> characters; these 15 characters are formulated based on specific features of the flea morphology and describe interrelations of the skeletal structures (or microstructures of a particular formation). For multi-aspect characteristics of different character states of some structures a concept of a «structural type» is used. Homoplasies of various levels comprise over one-half (53 %) of all character states in the head structure. Character states that reflect phylogenetic closeness of taxa amount for about 22 %.