Abstract: In the mingming cicada Oncotympana maculaticollis Motsch, the sounding muscle consists of 193 primary myobandles on average, with the majority containing 7-10 muscle fibers. The sticking structures of top and bottom muscle fibers consist of a layer of adhesion pillar cells. Each muscle fiber contains about 1800 myofibrils, and in the majority of them the length, width and cross section area are about 0.77μm,0.68μm and 0.53μm2, respectively. Each myofibril contains about 200 thick filaments and the ratio of thin to thick filament is commonly 3:1. The sacromere length and Z-line width are about 3μm and 0.2μm respectively, and two triads are separately about 0.75μm distant from both ends of Z-line. The areacoefficients of myofibril, mitochondra and tracheole-sarcoplasmic reticulum are about 31.3%,46.0% and 11.9%, respectively. In the sarcomere, thick filaments run through two ends of the Z-line without l-band in the middle, and thin filaments stretch oppositely from two ends of Z-line to the middle and the gap is about 0.15-0.25μm. The M-line is absent. These structural characteristics not only enable the sounding muscle to make enough use of limited spaces and to produce maximal tensions, but also to adapt contraction movements of high speed.

Key words: Oncotympana maculatieollis Motsch. Sounding muscle, microstructure, sounding function