Fine structure of the mouthparts of Diostrombus politus and Proutista moesta (Hemiptera: Derbidae)

Insect mouthparts are important sensory and feeding structures, morphological studies of this organ can provide additional data for phylogenetic studies. The planthopper superfamily Fulgoroidea is among the dominant groups of phytophagous insects, however, the mouthparts ultrastructure of this superfamily remains unsatisfactorily studied. This study investigates the ultrastructure of the mouthparts of two species in the family Derbidae (Hemiptera: Fulgoroidea), Diostrombus politus Uhler and Proutista moesta (Westwood), using a scanning electron microscope. The results show that these two derbids are of a typical piercing-sucking type found in Hemiptera. They consist of a cone-shaped labrum, a three-segmented labium and a stylet fascicle with two interlocked maxillary stylets incompletely wrapped by two mandibular stylets. The arrangement of the sensilla on the labial tip differ slightly between the two derbid species, and the subapical labial sensilla are likely different among genera in the family Derbidae.