Abstract: The morphology of the jaws and denticles ofSinospelaeobdella wulingensisandHaemadipsa tianmushanawas examined using stereomicroscopy and scanning electron microscopy. The main results showed that inSinospelaeobdella wulingensis, the triple jaws were minute and soft in texture, with large spacing between the jaws, and with approximately 80－90 denticles in a single row on the free margin of the jaws. In contrast, inHaemadipsa tianmushana, the triple jaws were well-developed, and hard in texture, with small spacing between the jaws, and with approximately 110－120 denticles in a single row on the free edge of the jaws. Salivary gland secretory pores were exclusively observed at the base of adjacent denticles inHaemadipsa tianmushana. The morphological features of the jaws and the number of denticles of leechers were closely related to their feeding habits. WhileH. tianmushanais an obligate blood-feeder,S. wulingensisis a facultative blood-feeder. These differences suggested morphological adaptations have occurred in their jaws and denticles of these two species. This study provided new morphological evidences for distinguishingSinospelaeobdellafromHaemadipsa, and contributes to further investigation on taxonomy, functional morphology, behavioral ecology and evolutionary ecology for Haemadipsidae.

Key words: Sinospelaeobdella wulingensis;Haemadipsa tianmushana, jaw, denticle, blood-sucking, Haemadipsidae