Galeal Tip Sensilla of a Carnivorous Stonefly Nymph, Perla Marginata (plecoptera: Perlidae)

The distal part of the galea belonging to the nymphs of carnivorous stonefly species – Perla marginata (Pictet, 1833) was studied by means of a scanning electron microscope (SEM). This species develops water-living, active and tactile predator nymphs, which use their mouthparts sensilla “to touch”, “to taste” or “to smell” the food and the substrate. The maxillary and labial palps, galea, glossa and paraglossa end with sensory complexes involved in the detection of the chemical qualities of the substrate and of the pray. This paper presents the external morphology of the tip of the galea, and describes the main types and the distribution of its sensilla. The tip of galea is a distinct region, having an oval-plate form, oblique, limited by a semicircular cuticular ridge. There is a relative similarity between the position, external morphology and the general structure of the apical sensillar complexes of the galeea and the glossa/paraglossa tips. The apical sensillar complex of galea contains a group of sensilla styloconica, rare short and many long sensila chaetica and rare sensilla trichodea. These apical structures developed the chemosensory and mechanosensory functions.