Title

Life History Information On Some Strigeoids Parasitizing Pond-Raised Catfish: A Synergism of Morphology and Molecules

Date of Award

2001

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Coastal Sciences, Gulf Coast Research Laboratory

First Advisor

Robin M. Overstreet

Advisor Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

Portions of the life histories of five strigeoid species parasitizing pond-raised channel catfish (Ictalurus punctatus ) in Mississippi and Louisiana are investigated. Detailed morphological observations and DNA sequencing of segments of the COI, 18S rRNA, 28S rRNA, and ITS-1 genes related the diplostomulum with the corresponding adult of four of the five strigeoid species. The encysted prodiplostomulum of Bolbophorus confusus is encapsulated under the skin and in the musculature of the caudal fin base and the head as well as in the mesentery, brain cavity, eye socket, and behind the operculum of the catfish; the adult parasitizes the white pelican ( Pelecanus erythrorhynchos ). COI sequence data suggests a morphologically indistinguishable adult of a different cryptic species of Bolbophorus in the white pelican. The diplostomulum of Austrodiplostomum compactum is found free in the vitreous humor of the eye of the catfish; the adult parasitizes the double-crested cormorant (Phalacrocorax auritus ), and the first intermediate host is a gyro snail ( Gyraulus sp .). The diplostomulum of Bursacetabulus pelecanus is found free in the brain of the catfish; the adult infects the white pelican, and the first intermediate host is a gyro snail (Gyraulus sp.). Bursatintinnabulus macrobursus and Bursacetabulus macrobursus are considered junior synonyms of Bursacetabulus pelecanus . Also, Bursatintinnabulus bassanus becomes Bursacetabulus bassanus n. comb. The genus Bursatintinnabulus is suppressed. The unencysted diplostomulum of Hysteromorpha triloba occurred deep within the musculature of the catfish; the adult parasitizes the double-crested cormorant. An unidentified diplostomulum of a species of Diplostomum is found free in the lens of the eye of the catfish; the adult of this species is unknown, but it is believed to parasitize a fish-eating lariform (gull, tern) bird. It is suggested that Diplostomum baeri of Inchausty, Foutz, Heckmann, Ruas, and Ruas, 1997 may not be D. baeri ( sensu stricto ). Evidence is presented supporting the view that there is more than one species of Diplostomum infecting the lens of the eye of fishes, and the use of the species, Diplostomum spathaceum , as a repository for any form of Diplostomum found in the eye lens of fishes is unfounded.