First-instar nymphal morphology and antennal sensilla in the Kerria lacca (Kerr, 1782) and Paratachardina mahdihassani (Kondo and Gullan, 2007) (Hemiptera: Tachardiidae)

The external morphology and antennal sensilla, in the first-instar nymphs of both Kerria lacca (Kerr) and Paratachardina mahdihassani (Kondo and Gullan) is analyzed using the scanning electron microscope. The studies reveal that first-instar nymphs could be differentiated based on characteristics of head, antennae, labium, brachial plate, anal region and associated structures. Among these the most significant ones of descriptive significance include dorsal setae on head, number and arrangement of antennal sensilla, number of labial sensilla, quinquelocular spiracular pores and pseudospines on brachial plate and anal fringe nature, i.e., sharp, acute setae or broad plates. Six morphologically distinct types of sensilla viz., sensilla trichodea, basiconica, chaetica, coeloconica, campaniformia and flagellate are identified and described. The arrangement of these and their probable functions are discussed relating to morphology and location. The types and arrangement of antennal sensilla are very similar in both the species studied, but the sensilla basiconica subtypes, i.e., sensilla basiconica type 2 (SB2) and sensilla basiconica type 3 (SB3) were restricted only to P. mahdihassani.