Detection of Ichthyophonus by chromogenic in situ hybridization

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.