MORPHOLOGY OF SENSORY ORGANS ON ROSTRUM A PEX OF TERRESTRIAL BUGS (HEMIPTERA)

Morphology, numbers, and distribution of sensilla on the rostrum apex of bugs, which consists of two lateral lobes (paraglosses) and a centr al lobe, or apical plate (fused glosses), are described. The electron- microscopical investigation of 19 terrestrial bug species from 10 fami lies has shown that chemosensory organs of the rostrum are represented by 6-12 basiconic sensillae, which are arranged in the local sensory field of each lateral lobe. A sensilla is equipped with 2-6 sensory ne urons. Dimensions of the basiconic sensillae, their orientation about the rostrum axis, development of subsidiary structures (basal cylinder in Rhopalidae and Coreidae, microtrichii and long trichoid sensillae in Pentatomidae) have not only adaptive significance, but are correlat ed with phylogenetic position of bug families in the order Hemiptera. The degree of developing the chitinized and membranized parts of the a pical plate in bugs is related to the type and peculiarities of feedin g.