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The Site of Udonella caligorum (Trematoda) upon Parasitic Copepod Hosts

1961; University of Notre Dame; Volume: 66; Issue: 2 Linguagem: Inglês

10.2307/2423031

1938-4238

David Causey,

Aquatic Invertebrate Ecology and Behavior

literature indicates that Udonella caligorum tends to select the egg strings of the host copepod as a site of attachment in European waters, and the body of the copepod in American waters. Data for two species of parasitic copepods from American waters, having this trematode upon them, confirms the apparent choice of the body of the copepod as a site. Udonella caligorum Johnston, 1835 is a small leech-like parasitic trematode which apparently spends its entire life upon various species of parasitic copepods of marine fish. It has been reported from European waters (Dawes, 1946); the Atlantic Coast of the U.S. and Canada (Dawes, 1946; Price, 1938; Tortugas (Price, 1938) and Port Aransas, Texas (Causey, 1956) in the Gulf of Mexico; and Monterey Bay, California, (Guberlet, 1936). I add two new records, Ocean Springs, Miss., and Georgetown, British Guiana. Most of the fish hosts and the parasitic copepods mentioned in the literature are cited (Table I). fish listed are all marine, and include both cold water and warm water types, ranging widely over the class. Three suborders (following Wilson, 1932) of parasitic copepods are included: the Cyclopoida, Caligoida, and Lernaeopo- doida. Free swimming caligids are often caught in the tow, and ap- parently, according to Dawes' record, the trematodes go with them. Price's careful survey and Dawes' tabulation make it evident that probably only one species of trematode is involved. To one interested in host specificity, ecological relations, and distribution, this associa- tion of so many kinds of fish and parasitic copepods, and a single species of trematode is surprising, if not improbable! With sufficient specimens of infested copepods, one can find all stages of the life cycle of the trematode from the stalked egg to the mature worm. Price states, The life history of this species, so far as represented in the available material, is essentially the same as that given by van Beneden (1858). Van Beneden gives more stages (less clearly) than Price; Dawes copies Price's figures. one point in the life cycle which is not evident is the transfer from copepod to copepod. Van Beneden thought the change took place during the free swimming stage of the copepod. That this could occur, unless the transfer took place during coitus of the copepods, seems unlikely. All example of coitus I have found thus far, admittedly few, were taken from the fish surface and not from the plankton. One can consider the possibility, on the basis of free swimming copepods carry- ing the trematodes, that the transfer occurs after the copepods have settled on the fish. I suspect that this occurs slowly, as I have several 314