Comparative Morphological Analysis of Two Species of Turtle Leeches Coexisting in North America (Hirudinea: Glossiphoniidae): Embryological Evidence for Character Displacement

The genus Placobdella (Glossiphoniidae) has a centre of species concentration in North America. type P. costata is the only representative Palaearctic region. American which feed on turtles are represented predominantly by two common species, parasitica and rugosa, geographically overlap eastern USA southern Canada. latter morphologically indistinguishable from multilineata southeast USA. These tuberculated forms recognised herein as clade treated single ‘species’ for comparative purposes. Both rugosa commonly coexist same turtle without host preference. This paper addresses morphological differences between them. An unexpected finding that hatchlings both very difficult to distinguish. A significant observation developmental divergence results tubercle prominence clade, but suppression parasitica, first example character displacement Hirudinea. Morphological interpreted reflecting interspecific competition, phenomenon not found their counterpart. Why do leech rather than reduce competition partitioning food supply?