Labial Sensory Organs of Two Leptoglossus Species (Hemiptera: Coreidae): Their Morphology and Supposed Function

Abstract

A detailed description of the labial sensory organs of Leptoglossus occidentalis Heidemann, 1910 and L. zonatus (Dallas, 1852) (Hemiptera: Heteroptera: Coreidae) is presented. The detailed morphology, location, and distribution of different sensilla types on mouthparts were investigated and shown in micrographs taken with a scanning electron microscope. Nine types of aporous sensilla, and three uniporous sensilla were found. The possible functions of these sensilla as well as similarities and differences between the mouthparts of Leptoglossus and those of other terrestrial Heteroptera are discussed. The tip of the labium constitutes a functional “touch and taste area”, combining the chemosensitivity of uniporous sensilla P1–P3 and the mechanoreceptivity of A8 and A9 hair-like sensilla. A set of two cone-like chemosensilla types (9 + 2) was found on each lateral lobe of the labial tip. Literature analysis showed that such a set of cone-like sensory organs on the labial tip may be common in terrestrial Heteroptera. This observation confirms that the number and arrangement of sensilla is conservative and can be important in diagnosing taxa at various levels and in phylogenetic studies based on morphology.

Microstructural Adaptation for Prey Manipulation in the Millipede Assassin Bugs (Hemiptera: Reduviidae: Ectrichodiinae)

“…Labial sensilla of heteropterans are known to play an important function in host detection [25,38,40,54,55]. Adapted to stridulating by rubbing the tip of the labium against the transversely striate prosternal sulcus, sensilla on the labial tip in Reduviidae are relatively shorter and flatter than those in other terrestrial true bugs [12,56,57]. Labial sensilla of our surveyed millipede bugs are morphologically similar to those of H. nigrorufa and other reduviids [6,56].…”

“…The pores on the labial sensilla basiconica of H. nigrorufa support its chemoreceptor function [6]. Sensilla placoidea are also considered chemoreceptors, and most true bugs have a single pair on the labial tip [6,[56][57][58][59].…”

Scanning Electron Microscopy of Antennae and Mouthparts of Mezira yunnana Hsiao (Hemiptera: Aradidae): Specialized Microstructures Reflecting Adaptation to Mycetophagy

“…The sensilla were classified according to their external morphology, distribution, and position. For classification of sensilla, the systems of Altner and Loftus [28] were used in addition to the more specialized nomenclature from other studies [5,20,29].…”

“…In this study, three subtypes of labial sensilla trichodea (LaTr I-III), three subtypes of labial sensilla basiconica (LaBa I-III), and a labial sensilla campaniformia (LaCa) of M. yunnana were distinguished based on morphological characteristics. Combined with previous studies [5,13,14,29,[36][37][38][39][40], their potential functions are summarized (Table 2). Sensilla basiconica on the labial tips are hypothesized to carry out a contact-chemoreceptive function [5,13,14,16,29].…”

“…Combined with previous studies [5,13,14,29,[36][37][38][39][40], their potential functions are summarized (Table 2). Sensilla basiconica on the labial tips are hypothesized to carry out a contact-chemoreceptive function [5,13,14,16,29]. Interestingly, only three pairs of LaBa III near the opening at the labial apex, which is much less compared to other previously examined phytophagous or predaceous pentatomomorphans.…”