Distribution and innervation of sensilla on the mouthparts of the carnivorous stonefly nymph, Paragnetina media (Walker) (Plecoptera: Perlidae)
The external morphology and distribution of various types of sensilla on the mouthparts of the nymphs of Paragnetina media are described, based on light and scanning electron microscopy. Hairs of various types are arranged in distinctive patterns on each mouthpart. Scolopophorous sensilla, each consisting of a pore canal and two bipolar neurons, are present in the mandibular teeth. The elliptical type of campaniform sensilla, multiporous columnar pegs, and nonporous sensilla are concentrated on the segments of the maxillary and labial palps. The tips of the maxillary and labial palps bear a cluster of uniporous multidigitate pegs, a multiporous peg, a circular type campaniform sensillum, and several nonporous sensilla. Nonsocketed uniporous pegs crown the tip of galeae and are also scattered over the surface of the glossae and paraglossae. Possible functions of these sensilla are discussed. A cleaning method is described to visualize details with the scanning electron microscope.