Glossiphoniidae

Glossiphoniidae are a family of freshwater proboscis-bearing leeches. These leeches are generally flattened, and have a poorly defined anterior sucker. Most suck the blood of freshwater vertebrates like amphibians, crocodilians and aquatic turtles, but some feed on invertebrates like oligochaetes and freshwater snails instead. Although they prefer other hosts, blood-feeding species will opportunistically feed from humans. There is considerable interest in the symbiotic bacteria that at least some glossiphoniids house in specialized organs called bacteriomes. The bacteria are thought to provide the leeches with nutrients that are scarce or absent from their regular diets. Haementeria as well as Placobdelloides have Enterobacteriaceae symbionts, while Placobdella harbours peculiar and independently derived alphaproteobacteria.

The relationships between members of Glossiphoniidae are not completely understood. Constituent genera include:

Alboglossiphonia Batracobdella Batracobdelloides Boreobdella Glossiphonia Marsupiobdella Placobdella Blanchard, 1893 – includes Desserobdella Barta & Sawyer, 1990 and Oligobdella Moore , 1918, formerly in Glossiphoniinae (see de Carle et al. for more recent work on this genus ) Placobdelloides Sawyer, 1986 – possibly paraphyletic or polyphyletic Theromyzon Torix

Glossiphoniid leeches exhibit remarkable parental care, the most highly developed one among the known annelids. They produce a membranous bag to hold the eggs, which is carried on the underside. The young attach to the parent's belly after hatching and are thus ferried to their first meal. Certain Glossiphoniidae parasitize amphibian species. For example, some members of the Glossiphoniidae are known to attack the inner oral cavity of the Rough-skinned Newt.C.M. Hogan, 2008

While glossiphoniids do not preferentially feed on humans, they are nonetheless of medical interest. As with all blood- or haemolymph-feeding leeches, their saliva, contains anticoagulant compounds which are potentially useful in therapy of some cardiovascular diseases. Antistasin and related inhibitors of thrombokinase a such as ghilanten, lefaxin and therostatin have been derived from Haementeria species and Theromyzon tessulatum. These substances also may prevent certain tumors from metastasizing. Also from Haementeria are the fibrin stabilizing factor a inhibitor tridegin, a platelet adhesion inhibitor (leech anti-platelet protein; LAPP), and the fibrinogen-dissolving enzymes hementin and hementerin. T. tessulatum also yields therin, theromin and tessulin, which inhibit protease activity. Ornatins, which are antiplatelet glycoprotein IIb-IIIa antagonists, were discovered in Placobdella ornata, and several species have yielded hyaluronidases.