Light and electron microscopic study of a myxosporean, Tetrauronema desaequalis n. sp. (fam. Tetrauronematidae), from an Amazonian fish.

Tetrauronema desaequalis n. sp. described from the bases of the ventral fins of the teleost Hoplias malabaricus Boch, 1794, was collected in an estuarine region of the Amazon river near Belem, Brazil. This myxosporean produces large cysts (1-2 mm in diameter) that represent plasmodia containing all life cycle stages, including spores. Spores averaged 22.5 microns in total length and possess 2 pairs of posterolateral unequal projections extending from beside the sutural ridges near the terminus of the shell valves. The spore body was ellipsoidal and laterally compressed. Spore bodies measured 13.6 microns in length, 6.5 microns in width, and 3.7 microns in thickness. The 4 projections averaged 13.0, 12.2, 7.2, and 5.1 microns in length. The ellipsoidal polar capsules (7.0 x 2.6 microns) possessed a polar filament with 9-11 turns.