A Redescription of Myxobolus inornatus from Young-of-the-Year Smallmouth Bass (Micropterus dolomieu  )

• Published in: The Journal of parasitology 2012-12, Vol.98 (6), p.1236-1242
• Main Authors: Walsh, H. L, Blazer, V. S, Iwanowicz, L. R, Smith, G
• Format: Article
• Language: English
• Subjects: Agnatha. Pisces; Alternative music; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Base Sequence; Bass; Bass - parasitology; Bayesian analysis; Biological and medical sciences; DNA, Ribosomal - chemistry; Epidermis; Fingerlings; fins; Fish; Fish Diseases - parasitology; Fish Diseases - pathology; Fresh water ecosystems; Freshwater; Freshwater bass; Freshwater fishes; Fundamental and applied biological sciences. Psychology; gene sequence; General aspects; General aspects and techniques. Study of several systematic groups. Models; Infections; Invertebrates; Micropterus dolomieu; Micropterus salmoides; Molecular Sequence Data; Morphology; mortality; Muscle, Skeletal - parasitology; Muscle, Skeletal - pathology; muscles; Myxobolus; Myxobolus - anatomy & histology; Myxobolus - classification; Myxobolus - genetics; nucleotide sequences; Parasites; Parasitic Diseases, Animal - parasitology; Parasitic Diseases, Animal - pathology; Parasitology; Peduncle; Pennsylvania; Phylogeny; redescriptions; Ribosomal DNA; Rivers; Sequence Analysis, DNA - veterinary; Spores; Spores - classification; Spores - ultrastructure; Subcutaneous Tissue - parasitology; Subcutaneous Tissue - pathology; Synecology; SYSTEMATICS-PHYLOGENETICS; Vacuoles; vertebrae; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
• ISSN: 0022-3395; 1937-2345
• DOI: 10.1645/GE-3081.1

During investigations of young-of-the year smallmouth bass (Micropterus dolomieu) mortalities in the Susquehanna River, Pennsylvania, U.S.A. and affected tributaries, raised areas were noted in the muscle in the vicinity of the caudal peduncle. The raised areas were caused by plasmodia of a myxozoan parasite. Spores found within plasmodia were similar to those of Myxobolus inornatus previously described from the caudal peduncle of fingerling largemouth bass (Micropterus salmoides) in Montana. Here, M. inornatus is redescribed based on histologic comparisons and spore measurements. The addition of spore photographs, line drawings, a voucher specimen, and partial small-subunit ribosomal (rSSU) DNA gene sequence are new in this study. This is also the first description of M. inornatus from smallmouth bass. The plasmodia of M. inornatus were grossly observed at the base of the caudal and dorsal fins and were 280.3 ± 33.5 (range 77.1–920.3) μm long and 320.6 ± 41.0 (range 74.85–898.4) μm wide. In some instances, plasmodia of M. inornatus were large enough to rupture the epidermis or were associated with misaligned vertebrae. The slightly pyriform spores were 11.3 ± 0.2 (range 8.6-17.4) μm in length and 8.6 ± 0.2 (range 7.1–13.7) μm wide with an iodinophilous vacuole and a sutural ridge with 8 to 10 sutural folds. The SSU rDNA gene sequence places M. inornatus in a sister group with Myxobolus osburni.