Recently, in the course in investigating the parasites of Gobiomorphus cotidianus McDowall, 1975, the common bully, I noticed an inclusion within the gall bladder of a specimen from Lake Rotorua. On removal into saline, the gall bladder was opened, and a digenetic trematode was found within.

After fixing the parasite in 2% formalin in glacial acetic acid, and staining with Semichon's carmine, I identified it as Deretrema philippae Hine, 1977 (Fig 1).

To date, this species has been reported from a single species of fish, Galaxias divergens, the dwarf galaxius, and only from the Hinau stream in the Wairarapa, (Hine, 1977), although McDowell (1978) mentions that a Deretrema sp. had been found in the gall bladders of Galaxias brevipininis, and Gobiomorphus hubbsi.

That this parasite is found in a fish from a large lake and river system shows that C. philippae is much more widespread than previously indicated.

At present, New Zealand is the only place where Deretrema spp. have been reported from freshwater fish, or from the fish families Galaxiidae and Eleotridae.

References

Hine, P. M. 1977 Two new Digenean trematodes from New Zealand freshwater fishes. Journal of the Royal Society of New Zealand, 7(2): 163-170.

McDowall, R. M. 1978 New Zealand Freshwater Fishes. Heineman Educational Books (N.Z.) Ltd., Auckland 230 p.

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