Comparative structural analysis of jaws of selected blood-feeding and predacious arhynchobdellid leeches (Annelida: Clitellata: Hirudinida)

Morphological traits of jaws, denticles and salivary pores in jawed leeches are compared and an overview of their structural and functional properties is given. The species studied include Hirudo medicinalis , H. verbana , H. orientalis , H. nipponia , H . troctina , Limnatis nilotica , Haemopis sanguisuga and Whitmania laevis. Morphological descriptions are based on scanning electron microscopy and translucent light microscopy. All the species possess denticles arranged in one or two rows on muscular jaws with salivary pores between neighboring denticles. Structural differences of the denticles occur between the genera Hirudo , Limnatis and Haemopis , while within a genus, denticle structure is similar. In Hirudo spp., denticles are complex organs consisting of two subunits. Denticles of Limnatis nilotica are simple in their structure. Denticles and salivary pores of Haemopis sanguisuga have the largest size and the most complex structure as compared with the other species. Those denticles are heart-shaped; two rows of them coalesce into a single row. Salivary canals open through multiple pores arranged in a number of patches and leading into large common openings located between the denticles. The denticle sizes and numbers were found to correlate negatively: species with larger denticles have a fewer number of them.