Wednesday, July 2, 2008

American Society of Parasitologists Award for Leech Research

The best student paper presentation at the 87th Annual American Society of Parasitologists went to Anna J. Phillips for her present entitled "Hirudinidae3: Towards a Revision of the World's Medicinal Leeches". Here's the abstract...
Hirudindae contains the most notorious of the bloodfeeding leeches, the medicinal leeches. These worms gained in popularity with physicians practicing bloodletting, or phlebotomy, due to anticoagulants in the saliva that causes the bite to bleed freely, even after the leech has left. This treatment was performed worldwide, for centuries, with a member of the Hirudinidae native to the area. While a higher-level analysis of the Arhynchobdellidae, by Borda and Siddall (2003), found that the Hirudinidae is surprisingly comprised of two groups, this more intensely focused preliminary analysis shows that the Hirudinidae is actually split among three groups. A morphological analysis of twenty-two morphological characters, based on jaw dentition, sexual anatomy, and external morphology, failed to provide a resolution for most of the relationships in the family. DNA sequence data from nuclear 18S rDNA, nuclear 28S rDNA, mitochondrial 12S rDNA, and mitochondrial cytochrome c oxidase subunit I, were examined separately, and in combination, in a parsimony analysis. This analysis of representative species of the Hirudiniformes indicates that the world’s medicinal leeches comprise multiple independent groups. Clade membership is only partially indicated by continental origin. The African Hirudinidae are split between two clades, with the unexpected results of the North African and Eastern European taxa being sister to select genera of Central and South America, one of which is a new genus with a unique morphology among leeches. These results suggest that, what was previously considered the family Hirudinidae, is actually 3 families: the Macrobdellidae Richardson, constituted by most New World taxa; the “true” Hirudinidae, with the type species (Hirudo medicinalis); and a new family, including the subset of African species grouped with Limnatis nilotica and associated New World taxa.

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