Which parasitic worm is that?

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A Neobenedenia species collected during a field trip to México, the centre of diversity for this monogenean parasite genus.

Parasitic worms that live on the external surfaces of fish are responsible for high levels of illness and death in farmed fish and aquaria worldwide.

Several of the most notorious of these problem-causing parasites are in the genus Neobenedenia. Significant outbreaks of Neobenedenia have resulted in the loss of valuable cultivated fish stock in land-based facilities in Western Australia, sea-cage farmed barramundi off Queensland and may also pose a problem to wild fish populations.

Determining which Neobenedenia species cause problems for fish is not an easy task. Many individual Neobenedenia species have very similar physical characteristics. They also lack a preference for a specific host fish species which means that traditional identification methods cannot be used to work out which parasite species are dangerous and which are benign.

The Museum’s Parasitology Section has established exciting research collaborations with the Evolutionary Biology Unit (EBU) and other scientists around the world to tackle this problem. Principally, this study involved Associate Professor Ian Whittington, Principal Research Scientist in the Parasitology Section and Dr Terry Bertozzi, Research Scientist inBioinformatics in the EBU. The goal is to establish an integrated set of tools for identifying Neobenedenia species. While appearance will still be an important factor, other data such as development of genetic markers across all lifecycle stages of the parasite will be critical. Ian and Terry have been helping an external PhD student, Alex Brazenor, from James Cook University, who is studying some aspects of a Neobenedenia species for his doctorate project.

Once a panel of identification tools for Neobenedenia species is established, it can then be applied to tackle problems encountered in fish farms and public aquaria and will also be useful to quarantine and customs staff.

Whittington, I. D. and Bertozzi, T. Does Australia share pathogenic parasite species with the world?: Identity and systematics of a monogenean flatworm genus from marine fishes. Project currently being planned.

A Neobenedenia species.

A Neobenedenia species photographed alive from barramundi in north Queensland.  There are few robust morphological features on which to base distinctions bewteen ‘species’.