Of tie fifteen species of flukes referred to the genus Haematoloechus Looss. 1899, in Canada and the United States, nine are considered to be synonyms of one or another of the six species considered to be valid. Species identification is primarily based on the ratio of the transverse diameter of the oral sucker to the acetabulum (0/A), the anterior extent of the extracaecal loops along the ovary or testes, and orientation of the testes. The species considered valid are: H. longiplexus Stafford. 1902: H. breviplexus Stafford, 1902; H. varioplexus Stafford, 1902 (= H. similipiexus, = H. parviplexus, = H. buttensis, = H. floedae, = H. uniplexus ): H. medioplexus Stafford. 1902: H. complexus (Seely, 1906) (H. coloradensis, = confuses, = H. oxyorchis ); H. kernensis Ingles, 1932 (= H. tumidus ). Flukes are discussed using the name previously considered valid. H. buttensis, experimentally reared in the laboratory, was used to study morphological variations resulting from changes in technical procedures and environment. Techniques used to prepare study specimens of flukes affected some taxonomic characters previously used to separate species. The presence of spines, position of oral sucker, and size of flukes were affected by temperature of fixative, and the use of distilled water. Pressure added to the coverslip affected length and width of ovary, testes, sucker, and body., The size of flukes, experimentally reared in the frog, R. pretiosa, was affected by temperature at which the host was maintained, the numbers of metacercariae fed to frogs, and the age of the worm. Host size and sex had no apparent influence on fluke morphology. Sixty-day-old flukes were experimentally reared in either R. pretiosa, B. boreas, R, clamitans. or R. aurora. The effects of developing in different frog hosts were to alter the anterior extent of the extracaecal uterine loops relative to the posterior testis, the distribution of the vitellaria, and the size and shape of ovary, testes, and size of the body and suckers. The 0/A ratio remained relatively uniform in flukes from all hosts. Flukes recovered from frogs fed infected dragonflies had a larger body size (length and width), larger testes and ovaries, and had extracaecal loops reaching farther along the posterior testis than did flukes recovered from frogs fed infected damselflies. The O/A ratios for H. longiplexus, H. breviplexus, H. complexus, H, buttensis, H. coloradensis, and H. medioplexus did not vary among specimens collected from different localities. No significant difference in this ratio occurred between flukes that had inhabited more than one host. The O/A ratio of H. parviplexus was significantly greater when R. sylvatica was the definitive host than when R. catesbeiana was the host. This ratio also differed significantly between specimens collected from two localities in Nebraska, even though the host in both localities was R. catesbeiana. Pooled data for H. varioplexus and H. similiplexus indicated that flukes from R. catesbeiana. R. clamitans. R. pipiens, and B. woodhousei differed in their 0/A ratios and egg lengths and widths. Ovary and testes may be lobed or unlobed. Uterine loops extend from the posterior portion of the worm to near the anterior border of the anterior testis in H. varioplexus, H. buttensis, and H. parviplexus. The ext r a caeca1 loops reach to the posterior border of the ovary in H. breviplexus and beyond the anterior border of the ovary in H. longiplexus. In flukes containing extracaecal uterine loops, the left loop vas absent in 4.2% of the H. parviplexus and 8.3% of H. varioplexus examined, the right loop was absent in 9.0% of H. buttensis examined. Egg size (length and width) did not vary geographically in H. longiplexus, H. complexus, H. breviplexus, H. buttensis, H. coloradensis, or H. medioplexus. Egg lengths of H. parviplexus differed in flukes from R. sylvatica and R. catesbeiana. / Science, Faculty of / Zoology, Department of / Unknown

Thesis (Ph. D.)--University of Michigan, 1931. / Cover title. "Reprinted from Transactions of the American Microscopical Society, vol. L, no. 3, July, 1931." "Literature cited": p. 271-272.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed on Nov. 10, 2006). PDF text: xiii, 198 p. : ill. ; 9.99Mb. UMI publication number: AAT 3214778. Includes bibliographical references. Also available in microfilm, microfiche and paper format.

Thesis (M.Sc. (Physiology)) --University of Limpopo, 2015 / Water is an essential and yet scarce resource, which has a vital role for human use and also serve as a habitat for numerous organisms in aquatic environments. Despite its scarcity there have been many reports indicating that it is continually polluted by domestic, agricultural, mining and other anthropogenic activities; subsequently affecting the health of organisms residing in such water bodies. Fish have been selected as the bio-monitoring species due to its direct interaction with the environment; thereby making it an appropriate model to monitor and evaluate the health status of the environment. The feral population of the alien species, Hypopthalmichtys molitrix (Valenciennes, 1844) commonly known as the silver carp in Flag Boshielo Dam has been considered a healthy population. However, this perception changed considerably after reports of lethargic, dying fish were first noted in 2011. Currently the sporadic deaths amongst mature specimens (>0.7m) persist; and the reason(s) for their demise remains unclear. Therefore, the aim was to employ a seasonal study design to investigate the health status of selected fish species such as H. molitrix in Flag Boshielo Dam by evaluating haematological parameters, oxidative stress biomarkers and bio-accumulation levels of particular transition metals. Seasonal surveys were carried out from February 2012 to January 2013 at Flag Boshielo Dam, Olifants River System, Limpopo Province. The locality surrounding the dam is known to be in an agriculture and mining catchment. Hypopthalmichtys molitrix and Labeo rosae (Steindachner, 1894) commonly known as the rednose labeo were collected with the use of scoop nets, conventional angling gear and gill nets. Following collection, morphometric measurements were taken and blood was collected. The blood samples required for further analysis at the Medical Science Department, University of Limpopo were kept on ice (4˚C). After the collection of all blood samples the specific fish was sacrificed and muscle samples were collected for bio-accumulation analysis and gills and liver samples were collected for the measurement of oxidative stress biomarkers. These tissue samples were rapidly frozen and kept frozen (-85˚C) until further analysis. Haematological parameters from the study reflected a variation amongst comparison of the inter- and intra-species. It was observed that mature H. molitrix suffered from anaemia. The response of glutathione-S-transferase (GST) and thiobarbituric acid reactive substances (TBARS) was relatively constant throughout all seasons when the young (<0.5m) and mature H. molitrix (0.6 – 0.90m) specimens were compared. However, the catalase (CAT) response of mature H. molitrix was dramatically impaired. This would increase their vulnerability to oxidative stress. Bioaccumulation levels of the eleven selected transition elements exhibited various trends. Metals such as Molybdenum (Mo), Vanadium (V), (Chromium) Cr, Cobalt (Co), Zinc (Zn), Cadmium (Cd) and Mercury (Hg) exhibited seasonal bio-accumulation levels that were in support of the various feeding behaviours of the fish species in this study. On the other hand, metals such as Manganese (Mn), Iron (Fe), Copper (Cu), Zinc (Zn), Cadmium (Cd) and Mercury (Hg) also illustrated the potential to be contributing factors in the death of the mature specimens. In conclusion, the findings from this study illustrate the complex nature of metabolic disturbances resulting in the death of mature H. molitrix specimens. It is clear that no single aspect investigated in this study could be solely implicated as the major cause of death. This multifactorial presentation necessitates further haematological assessment focussing on blood cell morphology and pathology, as well as investigations into other oxidative stress biomarkers in liver and gill tissue. In addition, identifying the most appropriate tissue type for future bio-accumulation measurements of transition metals in this feral population is necessitated. It is further suggested that neuro-muscular assessments, focussing on neurotransmitters such as γ-aminobutyric acid (GABA) and acetylcholine (Ach), form part of the investigation into the lethargic behaviour of the mature fish.