A redescription of Discoverytrema markowskii Gibson, 1976 and description of D. gibsoni n. sp. (Digenea, Opecoelidae)
Both digenean species described occur in the intestine of the Antarctic gadiform fish Muraenolepis microps Lönnberg, 1905 off South Georgia. The original description of D. markowskii is here considered to be based on the specimens of two separate species. D. markowskii has lateral fields of vitelline follicles which are continuous, or with only small gaps, and separate anterior to the ventral sucker, the ovary consisting of 6–11 lobes and eggs 0.055–0.065 mm long. D. gibsoni n. sp. has lateral fields of vitelline follicles interrupted at the level of the ventral sucker and confluent dorsally anterior to the ventral sucker, the ovary compact or consisting of 2–4 lobes and eggs 0.067–0.073 mm long. Data on the prevalence and intensity of infection are given. D. gibsoni n. sp. was found to be the more common of the two species in the sample of fishes examined.