long. Males are much smaller (16 – 40 millimeters) and are relatively rare – in some species the male has never been described. Distribution Dracunculus worms are distributed globally, though each species has a narrower range. The majority of Dracunculus species described infect reptiles – predominantly snakes. These are spread across the globe, with D. ophidensis in the United States, D. brasiliensis in Brazil, D. coluberensis and D. alii in India, D. houdemeri in Vietnam, D. doi in Madagascar, D. dahomensis in Benin, D. oesophageus in Italy, and D. mulbus in Australia and Papua New Guinea. The only species known to infect a non-snake reptile is D. globocephalus which has been described in snapping turtles in the United States and Costa Rica. Most mammal-infecting species are in the Americas, with D. insignis infecting several wild and domestic mammals in the United States and Canada, D. lutrae infecting river otters in the United States and Canada, and D. fuelleborni infecting big-eared opposums in Brazil. The major exception is D. medinensis, by far the most studied Dracunculus as it infects humans. D. medinensis was historically widespread in Africa and South Asia, but is now limited to dozens of cases annually in humans and domestic dogs, and may soon be driven to extinction. Species Reptile-infecting species There are 14 accepted Dracunculus species, 10 of which infect reptiles. Eurasia hosts several reptile-infecting Dracunculus species. D. oesophageus was originally described from the esophagus of a viperine snake Natrix maura, and has been described several times since. The remaining three Eurasian reptile-infecting species have been described a single time each: D. coluberensis from an Indian trinket snake, and D. alii and D. houdemeri from Checkered keelback snakes in India and Vietnam respectively. The only snake-infecting Dracunculus species known in North America is D. ophidensis. It was originally described in garter snakes in Michigan and Minnesota by Sterling Brackett in 1938, and has since been reported in blackbelly garter snakes from Mexico, as well as northern water snakes and a plain-bellied water snake in Michigan. D. brasiliensis is the only described snake-infecting Dracunculus in South America. It was described in 2009 based on a single female worm from an anaconda in Brazil, and has since also been found in a Brazilian brown-banded water snake. Several worms that appear to be from the genus Dracunculus have been described in Central America, South America, and the Caribbean; however, they