A new species of Henneguya, a gill parasite of Astyanax altiparanae (Pisces: Characidae) from Brazil, with comments on histopathology and seasonality

RESUMO

A new species of Myxosporea, Henneguya chydadea, is described parasitizing the gills of Astyanax altiparanae collected from a lake on Rio das Pedras farm near Campinas, state of Säo Paulo, Brazil. Of the fish examined, 88.3 percent had gills parasitized by myxosporeans. The prevalence of the parasite ranged from 80 percent in the spring and fall, 93 percent in the summer and 100 percent in the winter. The parasite induced the formation of white, oval-shaped cysts measuring 40-64 æm x 64-80 æm which deformed the gill lamellae, compressed the capillaries, and caused retraction of the neighboring lamellae. The mature spores were elongated and had two identical, parallel elongate polar capsules. Each capsule contained a polar filament with 9-10 turns. There was no mucous envelope or iodinophilous vacuole. Morphometric differences between this parasite and other species of the genus Henneguya indicated, that he parasite observed in A. altiparanae is a new species. This is the first report of a myxosporeanparasitizing A. altiparanae