Acanthocephala from lake fishes in wisconsin usa the giant nuclei pattern in neoechinorhynchus robertbaueri and neoechinorhynchus prolixoides neoechinorhynchidae
Amin, O.M.; Vignieri, J.C.
Proceedings of the Helminthological Society of Washington 53(2): 184-193
Numerical and structural variations in the giant nuclei of Neoechinorhynchus robertbaueri Amin, 1985 and N. prolixoides Bullock, 1963 collected from Erimyzon sucetta (Lacepede) in Silver Lake (Kenosha County), Wisconsin were systematically studied. Both species normally had 6 giant subcuticular nuclei and 3 giant lemniscal nuclei but yonger N. prolixoides had more than the usual 8 giant nuclei in the cement gland. Numerical variations were not related to season or worm sex. Neoechinorhynchus robertbaueri apparently do not reach the older adult stage. In most older adult N. prolixoides, the giant nuclei do not assume the prereproductive condition. Reproductive activity and growth proceed simultaneously in both species. Structural changes of giant nuclei of the various developmental stages are described. Some overlap of stages of giant subcuticular nuclei was observed in N. robertbaueri and attributed to the compression of its reproductive season into 2-4 months. No positional changes in the giant subcuticular nuclei occurred in either species. Qualitative findings support the hypothesis that changes in all 3 sets of giant nuclei are associated with the initiation and maintenance of reproductive activity of worms. The relationship between giant nuclei patterns and the synchronization of reproductive and generation cycles appear to be common in neoechinorhynchid acanthocephalans.