Abstract

In the present study, a new species, Thelohanellus muscularis n. sp. infecting head muscles of Labeo rohita (Family Cyprinidae) from Ranjit Sagar Wetland, Punjab, India has been described on the basis of its morphology, histopathology and molecular analyses. The plasmodia were visible with the naked eye in the head muscles (opercular region) as round whitish bodies. The size of plasmodia ranged 0.6-0.8 mm each containing about 80-100 myxospores. The myxospores were pyriform in shape, blunt at the anterior end measuring 9.20 ± 0.28 µm × 4.0 ± 0.15 µm in size. Polar capsule was elongately pyriform measuring 5.85 ± 0.08 µm × 3.10 ± 0.11 µm in size. The amplified 18S rDNA product was 900 bp (accession number KT387308). The phylogenetic analysis indicated 99% homogeneity with three other thelohanelloid species recorded from freshwater fishes in India, i.e., T. filli (KR340464) infecting gills of Labeo rohita, T. sp. RA (KR423868) infecting gills of Catla catla and T. jiroveci (KJ476885) infecting gills of Labeo rohita. The prevalence of infection was 25%. The plasmodia and numerous myxospores were recorded in intermuscular fibrillar space in histological sections. Phylogenetic analyses elucidated relationship of the newly described Thelohanellus muscularis to other Thelohanellus species and supported its position as an independent species.

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