John M. Aho

Parasite communities : patterns and processes

1 Patterns and processes in helminth parasite communities: an overview.- 2 Host populations as resources defining parasite community organization.- 3 Spatial scale and the processes structuring a guild of larval trematode parasites.- 4 Guild structure of larval trematodes in molluscan hosts: prevalence, dominance and significance in competition.- 5 Helminth communities in marine fishes.- 6 Helminth communities in freshwater fish: structured communities of stochastic assemblages?.- 7 Helminth communities of amphibians and reptiles: comparative approaches to understanding patterns and processes.- 8 Helminth communities in avian hosts: determinants of pattern.- 9 Helminth community of mammalian hosts: concepts at the infracommunity, component and compound community levels.- 10 Models for multi-species parasite-host communities.- 11 Free-living communities and alimentary tract helminths: hypotheses and pattern analyses.- 12 Concluding remarks.

THE PARASITE FAUNA OF THE AMERICAN ALLIGATOR (Alligator mississippiensis) IN SOUTH CAROLINA1

Twelve American alligators (Alligator mississippiensis) were obtained from three different areas of South Carolina. One species of pentastome (Sebekia oxycephala), two species of nematodes (Dujardinascaris waltoni and Multicaecum tenuicolle), four species of trematodes (Polycotyle ornata, Acanthostomum coronarium, Archaeodiplostomum acetabulatum and Pseudocrocodilicola americaniense) and one species of hemogregarine (Haemogregarina crocodilnorum) were recovered. Polycotyle ornata was observed only in alligators from Par Pond while P. americaniense was found in Par Pond and coastal hosts, A. acetabulatum from Kiawah Island and coastal alligators, and A. coronarium only at Kiawah Island. These patterns suggest disjunct distributions for the trematode species in South Carolina alligators. The other parasites were found in alligators from all three locations. The only parasite observed to initiate damage or lesions in the alligator was the pentastome.

Genetic differentiation among congeneric acanthocephalans in the yellow-bellied slider turtle

Allozyme variation in Neoechinorhynchus was used to examine the hypothesis that the occurrence of a single morphologically variable species may account for the observation of overlapping distributional patterns within the intestine of the yellow-bellied slider turtle (Trachemys scripta). Genetic analysis of 6 enzyme loci excluded the single species hypothesis and was consistent with the occurrence of 4 congeneic species within the turtle population. Discriminant analysis of multilocus genotypes, however, indicated that species designation based primarily on female body and egg morphology may not be error free

Bacteria Associated with the Tegument of Clinostomum marginatum (Digenea)

Adults of Clinostomum marginatum freshly collected from a heron, Ardea herodias, were examined using transmission electron microscopy. Specimens from the mouth of the bird were encrusted with bacteria that were not removed by washing unless the saline contained antibiotics. There was no evidence that the attached bacteria were damaging to the trematode tegument. Three species of Gram-negative bacteria were isolated from the worm surfaces and identified; Achromobacter sp. was present in pure culture on 4 of 6 original cultures and in mixed culture with Edwardsiella tarda and Enterobacter agglomerans in 2 cultures. These species and 3 unidentified species of bacteria were isolated from the oral epithelium of the heron. Microorganisms were not seen attached to the surfaces of worms recovered from the esophagus. Because E. tarda and E. agglomerans were the only species isolated from the heron esophagus, the intimate bacterial-worm association in the heron mouth may be due specifically to Achromobacter sp.

Host-parasite interface of the flukeCollyriclum faba (Bremser in Schmalz, 1831) as revealed by light and electron microscopy

Light and electron microscopy ofCollyriclum faba reveals that the dorsal tegument is highly convoluted, containing regular groups of between one and five spines. The thinner ventral covering has a less spiny surface with shallow infoldings. The lining of the capsule is characterized by numerous layers of collagen reflecting a strong cellular response by the host.