Detection of Ichthyophonus by chromogenic in situ hybridization

Abstract

Ichthyophonus hoferi (Plehn & Mulsow 1911 ) is a protistan parasite in the class Mesomycetozoea that infects a large range of marine and freshwater fish (Mendoza, Taylor & Ajello 2002 ; McVicar 2011 ). The broad host and geographic range, which includes both fresh and marine waters of the Northern and Southern Hemispheres, combined with a lack of distinguishing morphological characteristics, have prompted speculation that Ichthyophonus -like organisms in multiple species of fish, as well as reptiles, amphibians, birds and invertebrates, may have been incorrectly classified under a single type species I. hoferi (McVicar 2011 ). At present, only two species, I. hoferi and I. irregularis , are currently recognized within the genus (Rand et al . 2000 ; Mendoza et al . 2002 ). Investigations of ribosomal DNA sequence variation have begun to clarify relationships among Ichthyophonus types (Criscione et al . 2002 ; Rasmussen et al . 2010 ). Here, we will use the term Ichthyophonus to broadly represent all members of the genus regardless of species/subspecies.