A New Species of Myxozoan (Myxosporea) from the Brain and Spinal Cord of Rainbow Trout (Oncorhynchus mykiss) from Idaho

• DOI: 10.1645/ge-1292.1
• Publication Date: 2008-02-28T14:05:07Z
• Authors: Carla I. Hogge; Matthew R. Campbell; Keith A. Johnson
• Keywords: 0301 basic medicine; Idaho; Spores, Protozoan; Brain; Eukaryota; Central Nervous System Protozoal Infections; Sequence Analysis, DNA; DNA, Ribosomal; Polymerase Chain Reaction; 3. Good health; Fish Diseases; 03 medical and health sciences; Species Specificity; Spinal Cord; Oncorhynchus mykiss; Microscopy, Electron, Scanning; Prevalence; RNA, Ribosomal, 18S; Animals; Protozoan Infections, Animal; Phylogeny

A new species of Myxosporea, Myxobolus neurotropus n. sp., is described from the brain and spinal cord of rainbow trout (Oncorhynchus mykiss) from Duncan Creek, Owyhee County, Idaho. Spores are oval, have 2 pyriform polar capsules, and possess a thick spore wall (sutural rim) with a short intracapsular offshoot. The mean spore dimensions are length 11.8 microm, width 10.8 microm, and thickness 8.8 microm. This myxozoan is compared to other described Myxobolus species found in cranial tissues of salmonids in terms of spore morphology and phylogenetic analysis. Because it is found in brain and spinal cord, it is encountered while performing screening tests for Myxobolus cerebralis, the causative agent of salmonid whirling disease. Where chronic inflammation and granulomatous lesions are associated with M. cerebralis, histological examination shows no host response to M. neurotropus n. sp. A diagnostic polymerase chain reaction (PCR) test is included as an aid in properly identifying the species.