Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Seven species of Monogenea of the subfamily Ancyrocephalinae were collected from 700 Lepomis macrochirus from two eutrophic localities in southern Louisiana. Host specimens were collected monthly from May 1982 through April 1984 from Pat's Bay and Spanish Lake. The relative densities of nonlarval Onchocleidus ferox, Actinocleidus fergusoni, Haplocleidus acer, H. dispar, Anchoradiscus triangularis, Cleidodiscus robustus, and C. nematocirrus were analysed for correlation with water temperature, significant differences in locality, temporal and spatial dynamics, and effect of host sex on population densities. The three more abundant species, O. ferox, A. fergusoni, and H. acer, were warm-water forms, whereas H. dispar and A. triangularis were cold-water species. C. robustus favored warm water while C. nematocirrus did not show a preference. Significantly (P < .001) more specimens of O. ferox and H. acer were recovered from Spanish Lake than Pat's Bay. The second gill arch was preferred (P < .0001) by the three more abundant species, whereas the fourth arch was least preferred (P < .0001). Significant (P < .0001) differences in densities between gill arches two and four were observed for all the less abundant species, but densities on the second and fourth arches were not necessarily significantly different from the densities on gill arches one or three. All species preferred the anterior hemibranch of each gill arch (P < .0001). The medial section of the anterior hemibranch was most preferred by the majority of the species. Monthly gill arch and gill section distributional patterns of the more abundant species were consistent over the entire 24-month period with the exception of January and February, whereas monthly variations occurred among the less abundant species. Significantly more specimens of the more abundant species were found on female hosts. Distributional patterns of these worms on the gills of the host were not affected by the sex of the host.