|Cercaria larva of Bucephalus polymorphus from Encyclopædia Britannica, Eleventh Edition|
Bucephalus ("ox head") is the genus name for many trematode flatworms that are parasites of molluscs and fish. Like other Bucephalidae, they are found in fish both as adults and as metacercariae. In marine and freshwater teleosts, they live as parasites inside the digestive tract, especially the intestine.
The genus Bucephalus was based on the earliest known bucephalid, B. polymorphus Baer (1827), initially described from a cercaria larva. Siebold (1848) believed that the adult bucephalid he named Gasterostomum fimbriatum represented an adult form of the same bucephalid, but this identity has never been proved.
The name Bucephalus meaning "ox head" was chosen because of the horn-like appearance of the forked tail (furcae) of its cercaria. By what Manter calls a "curious circumstance", horns are also suggested by the long tentacles of adult worms.
An earlier name for this genus was Gasterostomum, given by von Siebold in 1848 to all adult trematodes with a ventral mouth. Odhner (1905) established two suborders of digenean trematodes called Gasterostomata and Protostomata. The two genera in Gasterostomata were Gasterostomum (now Bucephalus) and Prosorhynchus, of which the former has an anterior sucker separate from its digestive tract and the latter has an anterior rhynchus. Members of the genus Bucephalus are also sometimes referred to as "gasterostomes."
- "Bucephalus von Baer, 1827". ERMS. Retrieved 19 February 2011.
- Gibson, David I.; L. Margolis; Z. Kabata (1996). Guide to the Parasites of Fishes of Canada. 4. Canadian Government Publishing. pp. 39–40. ISBN 0-660-16403-5.
- Gibson, David Ian (2002). Keys to the Trematoda. CABI. pp. 74–75. ISBN 0-85199-547-0.
- Manter, Harold W (1940). "Digenetic trematodes of fishes from the Galapagos Islands and the neighboring Pacific" (pdf). Reports on the Collections obtained by Allan Hancock Pacific Expeditions, 1932-1938. 2 (14): 333. Retrieved 20 February 2011.