DAO 93:235-242 (2011)  -  DOI: https://doi.org/10.3354/dao02292

ABSTRACT: A new species of Myxosporea, Henneguya torpedo sp. nov., is described from the brain and spinal cord of the Amazonian teleostean fish Brachyhypopomus pinnicaudatus collected from the Peixe Boi River, State of Pará, Brazil. The spores were surrounded by a thick hyaline sheath that is homogeneous and electron translucent and consists of 2 layers of different densities. The total spore length is 48.62 ± 0.51 µm (mean ± SE), the ellipsoidal spore body length is 28.53 ± 0.36 µm, the body width is 7.25 ± 0.31 µm and the body thickness is 3.06 ± 0.26 µm. Each of the 2 equal-sized valves presented a tapering tail (19.64 ± 0.44 µm in length). The 2 equal-sized thin and smooth valves surrounded 2 equal-sized and elongated ellipsoidal polar capsules (6.41 ± 0.26 × 1.84 ± 0.19 µm) that contained 5 to 6 (rarely 7) polar filament coils. The binucleated sporoplasm contained numerous spherical sporoplasmosomes (~260 × ~280 nm) with a laterally eccentric-dense structure containing a half-crescent section. The sporoplasmosomes are surrounded by a hyaline homogenous sheath. Based on the data obtained by light and electron microscopy and on the host specificity, the spores differed from the previously described Henneguya spp., mainly in the presence of a sheath surrounding the spores, the spore shape and size and the number and arrangement of the polar filament coils. Therefore, from this description we propose the establishment of a new species, which we have named Henneguya torpedo sp. nov.

KEY WORDS: Nervous system · Teleost · Brachyhypopomus pinnicaudatus · Myxosporean · Spores · Henneguya torpedo sp. nov. · Ultrastructure