Acta Parasitologica, Vol. 52, No. 2, 2007, 89103. DOI: 10.2478/s11686-007-0016-1 Göran Malmberg1*, Catherine M. Collins2, Carey O. Cunningham2 and Behiar J. Jalali3 Gyrodactylus derjavinoides sp. nov. (Monogenea,
Platyhelminthes) on Salmo trutta trutta L. and G. derjavini Mikailov, 1975 on S. t. caspius Kessler, two different species of Gyrodactylus - combined
morphological and molecular investigations 1 Department of Zoology, Stockholm University, S-106 91 Stockholm, Sweden; 2FRS Marine Laboratory, P.O. Box 101, Victoria Road, Aberdeen, AB11 9DB, UK; 3 Veterinary Department, Research and Science Branch, Islamic Azad University, P.O. Box 14515 775 Teheran, Iran
*Corresponding author: email@example.com
The paper deals with two morphologically similar but molecularly clearly different species of Gyrodactylus: G. derjavinoides
sp. nov. on Salmo trutta trutta L. in Western Europe and G. derjavini Mikailov, 1975 collected on Salmo trutta caspius Kessler
in Iran. The new species is described and its opisthaptoral hard parts compared to those of G. derjavini. Our molecular analysis
of G. derjavinoides and G. derjavini confirmed that the morphological differences between them are species differences and
not intraspecific variations. Phylogenetic analysis using the ITS rDNA region placed both species within the subgenus G.
(Limnonephrotus) and within the G. wageneri-group, quite in accordance with morphological results. The two species, however,
did not cluster as sister taxa. The correspondence between molecular-based clades within G. (Limnonephrotus) and the
morphological shapes of marginal hooks within these clades are discussed. The importance of combined molecular and morphological
analyses when describing or redescribing Gyrodactylus species is stressed.
KEY WORDS: Platyhelminthes, Monogenea, Gyrodactylidae, Gyrodactylus sp. nov., fish, Salmo trutta, Western Europe, Iran