Morphological study of the labial sensilla in Nabidae (Hemiptera: Heteroptera: Cimicomorpha)

Abstract

The study presents new data on the morphology and distribution of the labial tip sensilla of six species of two nabid subfamilies—Protosteminae and Nabinae (Heteroptera: Cimicomorpha), which were obtained using a scanning electron microscope. In both taxa, there are five morphologically distinct types of sensilla on the tip of the labium: peg sensilla with a terminal pore, nonporous peg sensilla, elongated placoid sensilla with wall pores (multiporous), and trichoid sensilla. In addition, oval plate sensilla with a terminal pore (Tp-opls) were observed in the genus Himacerus. Campaniform sensilla and nonporous chaetic sensilla were observed on the surface of the last segment of the labium in all of the studied species. Over a dozen trichoid sensilla were scattered on the last segment of the labium only in the genus Prostemma. Based on their external structure, it is likely that these sensilla are chemosensitive and mechanosensitive. The oval plate sensilla with a Tp-opls (gustatory) in Himacerus (Nabinae) represent a morphological novelty that probably evolved independently of other nabids.