Morphology and Ultrastructure of the Salivary Glands of the Spittlebug Lepyronia coleopterata (L.) (Hemiptera: Aphrophoridae)
We investigated the salivary glands in Lepyronia coleopterata (L.), and found that the salivary glands are paired structures and consist of principal and accessory glands. Each principal gland contains an anterior lobe and a posterior lobe. Three types of acini (I, II, III) are observed in the anterior lobe, whereas the posterior lobe contains only one type of acini (IV). Rhabdus emerges from the middle portion of the acini III and IV. The oval-shaped accessory gland connects with the principal gland via a long duct. The long duct consists of a slightly coiled basal segment and a highly convoluted distal segment, with the terminal end of the latter constricted and connected with the accessory gland. A slightly convoluted transparent tube connects with the accessory gland at the former's distal end. The accessory gland, accessory salivary duct and the accessory salivary tube are observed for the first time in spittlebugs. Ultrastructurally, each type of acinus is made up of one type of secretory cells, but the rhabdus comprises two types of cells. Secretory granules in different type of cells are different in size, shape and electron density, which indicate either different materials are synthesized or these materials undergo a process of maturation. The rhabdus is empty in structure and contains several channels, with the lumen filled with abundant fine granular materials. Fine dark granules existed in the periphery of some secretory granules are probably virus particles. Microorganisms are observed in the cells of the acini I, III and rhabdus.