Monogenoidea on exotic Indian freshwater fish. 4. Dactylogyrus minutus from Platinum Ogon, an ornamental variety of the common carp Cyprinus carpio (Cypriniformes, Cyprinidae)

Abstract

Platinum Ogon, an ornamental variant of the common carp Cyprinus carpio, is one of the most expensive and sought-after pet fish. Multiple parasite species from Dactylogyrus and Gyrodactylus were recovered from Platinum Ogon specimens during an ongoing nationwide study of the monogenoidean parasites that infect ornamental fish imported into India. The morphological examination, combined with a DNA-sequencing analysis of the 18S–ITS 1 and 28S rRNA genes, identified Dactylogyrus minutus as one of these parasites, establishing this species’ presence in India for the first time. This finding is significant for two reasons. First, D. minutus has been associated with high death rates in carp fry. Second, Cyprinus carpio, its host, has established itself in Indian riverine waters. The nucleotide sequence of the 28S rRNA gene of D. minutus was phylogenetically compared to that of 19 other Dactylogyrus species from three fish families: Cyprinidae (10 species), Leuciscidae (six species), and Xenocyprididae (three species). The phylogenetic tree analysis revealed the monophyletic lineage of Dactylogyrus species from goldfish and common carp, which is likely due to the genetic relatedness of their hosts.