Scanning electron microscopy of Neoechinorhynchus sp. (Acanthocephala: Neoechinorhynchidae), a possible new species of intestinal parasite of the Tallfin croaker Micropogonias altipinnis (Günther, 1864)

Abstract

We describe an unidentified species of the genus Neoechinorhynchus occurring in the intestine of the marine fish Micropogonias altipinnis using scanning electron microscopy (SEM). The genus Neoechinorhynchus occurs mostly in freshwater fishes; this may be the first report of its occurrence in the marine fish genus Micropogonias and the New World Sciaenidae. The specimens collected have characteristics typical of the genus. The mean length of the trunk is 9.5 mm. The proboscis is short and subcylindrical measuring 70 µm in length and 50 µm in diameter near the base. The proboscis has three rings of curved spines each with six spines. The anterior spines are long measuring a mean of 55 µm in length, 9 µm in width, and 7 µm in depth, and are supported by simple unmodified roots. The spines of the middle ring are smaller and equivalent to 70% of the roots of the anterior spines. The spines of the posterior ring are much smaller than those of the anterior ring. The body surface lacks spines and consists of a series of folds. The estuarine habits of M. altipinnis and its ability to tolerate fresh waters may have facilitated its infection with a species of the primarily freshwater genus Neoechinorhynchus, as well as the possibility that this parasite can infect human beings from the consumption of this kind of croaker.