Morphofunctional aspects of the head capsule topography in Aculeata (Hymenoptera)]

According to degree of segmental fusion insect head is the most integrated part of the body. Head skeleton subdivides into capsule and skeleton of appendages. Exo- and endoskeleton (tentorium) of head capsule have complex segmental origin. Marked margins are generally absent between such traditionally discriminated capsule parts as clypeus, frons, vertex, occiput, genae, etc. Relative position to marked structures (appendages, eyes, ocelli, occipital foramen and etc.) defines the capsule parts, but homologization of last ones is complicated both by absence of substantive functions and complex segmental origin. Based on the technological point of view author characterizes head capsule construction in Aculeata. Capsule parts were studied as components of six technological systems associated with the head: maxillolabial, antennal, pharyngeal, optical, cranio-articulate and mandibular. Spatial relations, named by I.I. Schmalhausen as topographical co-ordinations, integrate head systems. Therefore relative position of the capsule parts incorporated in such systems is unvaried under any reconstruction. At the same time varieties of their forms and proportions reflect on form and topography of capsule as a whole. Comparative analysis of the capsule construction in Bethyloidea, Formicoidea, Sphecoidea, Vespoidea, Pompiloidea and Scolioidea has shown that many differences are determined by mutual modification of technological systems. In particular the increase in head elevation related with reconstruction of cranio-articulate system is accompanied with the shift of antennae to anterior end of the head. The capsule construction in Aculeata considered to be represented by hypognathous, prognathous and hypo-prognathous morphological types that determine head orientation towards longitudinal body axis. The role of topographical co-ordinations in formation of prognathous or hypognathous condition of the head in Aculeata is discussed.