Thelohanellus gabori sp. nov. (Myxosporea: Myxozoa) infecting gill filaments of a Cyprinid fish Crossocheilus latius (Hamilton, 1822) inhabiting a cold water wetland in Punjab (India).

A new myxobolid, Thelohanellus gabori (Myxosporea: Myxozoa) parasitizing gill filaments of Crossocheilus latius (Hamilton, 1822) has been described using light microscopy, histopathology, and molecular analyses. A total of 80 live specimens of C. latius were examined, revealing a prevalence of infection of 25.66% (21 of 80 fish sampled). The plasmodia were of intrafilamental epithelial type, FE as per their location in the gill filaments of the fish host. The plasmodia were cylindrical and creamy-white, 1.0-1.7 mm in diameter containing about 500-700 myxospores. The myxospores had a mean length of 8.56 ± 0.21 μm, width 3.66 ± 0.08 μm, mean length of polar capsule 5.50 ± 0.28 μm, and width 2.50 ± 0.14 μm. The 18S rDNA of Thelohanellus gabori sp. nov. (accession number KX757025) clustered phylogenetically with other related myxozoan parasites being T. pathankotensis and T. boggoti the most closely related species with 97% sequence similarity followed by T. sp. FCO with 89% sequence similarity. The mean abundance (gill plasmodial index) was calculated by counting the number of plasmodia on each side of the gill apparatus per host and was found to be 4 indicating severe infection causing fusion of many large-sized plasmodia in the gill filament. During the present study, it was found that the phylogenetic tree for Thelohanellus spp. depends upon the tissue location, vertebrate host group, and geographical region.