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Browsing Zoology and Entomology by Author "Basson, Linda"
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Item Open Access Aspects of the morphology, life cycle and epidemiology of Toxocara species and Toxascaris Leonina(University of the Free State, 2003-03) Tekele, Girma Mekete; Kok, Dawie J.; Basson, LindaEnglish: The present study has provided detailed and comprehensive information on the morphological aspects, life cycle, and epidemiology of Toxocara canis, Toxocara cati and Toxascaris leonina. The overall results of the study results are briefly summarized as follows: 1. In the morphological studies of these parasites, it has been observed that there are gross morphological similarities in the developmental stages of T. canis, T. cati and T. leonina. However, closer and detailed observations have revealed that the various developmental stages differ from one another in their fine morphological features. The observed morphological differences were: a. Eggs of T. canis and T. cati look very similar under the light microscope, in some eggs it seems that the surface pits and ridges of T. canis are larger and coarser than in the eggs of T. cati. However, unlike the eggs of Toxocara spp., eggs of T. leonina have no surface pits and ridges but are smoother on the surface. b. Second-stage larvae of T. canis recovered from the eggs and from the infected tissues of mice were stumpy and vigorously motile. The larval stages from both sources were similar in their morphological features and had comparable size measurements indicating that larval stages did not undergo development in the paratenic host. Like the larvae of T. canis, second-stage larva of T. cati recovered from the eggs and from the infected tissues of mice were stumpy and vigorously motile. The larval stages from both sources were similar in their morphological features and had comparable size measurements. The second-stage larvae of T. canis recovered from eggs or from tissues of mice had a greater width than the comparable second-stage larvae of T. cati. Unlike the larval stages recovered from the embryonated eggs of T. leonina, larvae recovered from infected tissues of mice were longer and wider and had more distinct morphological features. This indicated that larval stages recovered from the tissues of infected mice had probably undergone development to third-stage larvae. c. Adults T. canis, T. cati and T. leonina resemble each other in their gross morphological features, but also differ in their detailed and fine structural features. The major differences were on the shape of cervical alae, the presence or absence of an esophageal ventriculus, the position of the vulva in the female worms, as well as the number and arrangement of papillae on the tail of the male worms. d. Precloacal median papilla were recorded and described in males of T. canis and T. cati. Previous researchers did not describe the presence of these structures in male Toxocara spp. worms. In the present study, a female T. canis worm with a length of 27.5 cm was recovered from an infected dog and it was larger than any recorded in the literature. 2. In the study of the modes of transmission of ascarids, it has been observed that transplacental transmission of T. canis occurred in mice infected during but not before pregnancy. Transmammary transmission of T. canis and T. cati larvae had also occurred in mice infected prior to or during pregnancy. However, unlike in T. canis and T. cati, had neither transplacental nor transmammary transmission occurred in T. leonina. Larval stages were recovered from most tissues and organs of infected mice, and the larvae gradually accumulated in various extraintestinal tissues for the three ascarid species and especially in the brain of mice infected with T. canis. 3. The study on T. leonina transmission to the definitive hosts through experimentally infected mice as paratenic host, has indicated that dogs can be infected by ingesting infected tissues of mice that were infected with T. leonina infective eggs originally obtained from dogs. However, in cats this was not possible and it has been suggested that cats may not be the proper definitive host for T. leonina originating from dogs. 4. In an epidemiological survey of Toxocara spp. T. leonina, and other intestinal helminths of dogs and cats in Jimma, Southwestern Ethiopia, it was shown that the overall prevalence rates for parasitic infection were 60.78% in faecal samples of dogs from the environment, 78.60% in faecal samples of dogs taken from the rectum, 66.23% in faecal samples of cats and 33.38% in soil samples were recorded. Parasite species identified were Toxocara canis, T. cati, Toxascaris leonina, hookworms, Spirocerca lupi, Trichuris vulpis, taeniids, Ascaris species and Strongyloides species. A relatively high mean egg count of 15.25 was observed for T. canis in dog faecal droppings collected from the environment. The potential of these parasites as a cause of zoonotic infections, ways of prevention of infection and control measures were discussed.Item Open Access The biology of gnathiid isopod parasites and their role as vectors of fish blood parasites in South Africa(University of the Free State, 2000-12) Smit, Nicholas Jacobus; Van As, J. G.; Basson, Linda; Russell, Angela DaviesEnglish: Research on marine fish parasites has been largely neglected in South Africa. This is especially true for the temporary fish parasites of the isopod family Gnathiidae and fish blood parasites of the family Haemogregarinidae. In this study, surveys were carried out to determine the presence of gnathiid isopods and fish haemogregarines associated with different intertidal and sub-tidal fish hosts over a period of four years, at two different localities on the South African south coast. The study also focussed on the relationship between gnathiids and haemogregarines, specifically the possibility that the gnathiid Gnathia africana Barnard, 1914 might be a vector of the fish blood parasite Haemogregarina bigemina Laveran and Mesnil, 1901. Laboratory work was conducted to elucidate the life cycle of G. cfricana. It was found that G. cfricana has three larval stages, consisting of three unfed (zuphea) and three fed (praniza) stages, with the final stage praniza larvae moulting into either male or female adults. Forty days after their last feed as praniza 3 larvae, mature females release stage 1 zuphea larvae. Detailed information was also supplied on the feeding and digestion length for each larval stage. The females of G. africana were re-described from the material collected. Furthermore, other gnathiid larvae, not resembling any of the known species from South Africa, were collected from three species of elasmobranchs as well as the evileye pufferfish. Both groups of larvae were kept in the laboratory, where they moulted into adult males that did not conform to the description of any other gnathiid species in South Africa, or worldwide. These specimens were described as new species (Gnathia pantherinum sp. n. and G. pipindae sp. n.), using light and scanning electron microscope observations. Extensive information was also provided on the final life cycle stages of G panthertnum sp. n. Special attention was given to finding distinguishing characteristics to identify females and larvae of various species in the absence of males. Comparing material in this study with information from the literature showed that the morphology of the pleotelson and cephalosome appendages of females and larvae could be successfully used as differentiating characteristics. The research conducted on fish haemogregarines led to new distribution and host records for two known species, and the description of two new, but un-named species. Development stages of H. bigemina were found in the gut of G. africana larvae that had fed on H. bigemina-infected host fish. The data obtained from these results was used to compile a complete life cycle for H. bigemina in both the fish and the arthropod host.Item Open Access Blood parasites of Free State and Lesotho reptiles(University of the Free State, 2003-07) Van As, Johann; Davies, Angela; Basson, LindaEnglish: The study of blood parasites of reptiles is a relatively new and unexplored field of research in South Africa. The Free State province and the Lesotho highlands provide a range of reptiles in which their intraerythrocytic parasite fauna were explored. Objectives of this study were to set a baseline of blood parasite diversity and to identify the enigmatic Sauroplasma Du Toit, 1937 and Serpentoplasma Pienaar, 1954 infections in lizards and snakes, respectively. Surveys were conducted in various localities in the Free State and Lesotho. Although low in diversity, 204 specimens representing 14 species of lizards, and 59 specimens representing 13 species of snakes were investigated for the presence of blood parasites. Three known infections were found: Sauroplasma thornasi Du Toit, 1937, Sauromella haemolysus Pienaar, 1954 and Hepatozoon (Haemogregarina) sebae (Laveran and Pettit, 1909) Smith, 1996. These were redescribed and S. thomasii and H. sebae were examined by aid of transmission electron microscopy. The investigation led to the discovery of six new records and possibly new species of haemogregarines named Hepatozoon sp. A-F, four new records and possibly new species of lizard malaria named Plasmodium sp. A-D, and a viral infection possibly of the Pirhemocyton type. Furthermore nine new host and distribution records for Sauroplasma in lizards and nine for Serpentoplasma in snakes are described. Ultrastructural investigations of S. thomasi in Cordylus giganteus A. Smith, 1844, Serpentoplasma in Bitis arietans arietans (Merrem, 1820) and H. sebae in Python sebae natalensis (Gmelin, 1789) were the first to examine the nature of infections in this manner. This is the first comprehensive survey of the biodiversity of blood parasites in reptiles in the Free State and Lesotho highlands.Item Open Access Branchial monogenean parasites (Monogenea: Dactylogyridae) of characin fishes from the Okavango river and Delta, Botswana(University of the Free State, 1998-12) Christison, Kevin William; Van As, J. G.; Basson, LindaEnglish: The fishes of the Okavango System, Botswana, are of considerable economical and ecological importance. Recently, scientists and local fishermen have reported a dramatic decline in the fish stocks of the Okavango River and Delta. There are many reasons for this decline to which fish parasites ~may at least be a contributing factor. In recent surveys to the Okavango, monogeneans have been found to be of the most prominent parasites infesting the Okavango fishes. The tigerfish, Hydrocynus vittatus Castelnau 1861, especially, show high infestations of the branchial monogeneans, Annulotrema pikei (Price, Peebles & Bamford 1969). The genera Annulotrema Paperna & Thurston 1969 and Characidotrema Paperna & Thurston 1968, are exclusively parasites of characiform fish in Africa. In the Okavango the characiforms are represented by five species, Brycinus lateralis ( Boulenger 1900), Hepsetus odoe (Bloch 1794), Hydrocynus vittatus, Mieralestes acutidens (Peters 1852) en Rhabdalestes maunensis (Fowler 1935), all of which, are infested by species of the genus Annulotrema and only one, Brycinus lateralis (Boulenger 1900), is infested by a species of the genus Charcidotrema. During two field trips to the Okavango System, five Annulotrema species were collected; three of which are known species and two new species. This is the first record of monogeneans from Botswana and represents the southern most distribution recorded of A. curvipenis Paperna 1969 & A. hepseti Paperna & Thurston 1969. Comparative descriptions of the three known species are given and the two new species are described as A. micralesti sp. n. and A. rhabdalesti sp. n. Mixed infestations of A. curvipenis and Characidotrema nursei Ergens 1973 were also recorded from the gills of Brycinus lateralis. This also represents the southernmost, recorded distribution of C. nursei. Investigation of histological sections revealed that although these monogeneans occurred in relatively high numbers on the gills of the fish, the pathology they caused was limited. Examination of the infestation statistics showed that these parasites exhibit site preferences to the gills on which they occurred. This preference is influenced by the number of monogeneans of the same or other species as well as the number of other parasites occurring on the gills of the fish hosts. When considering the results, these monogenean parasites do not seem to cause severe harm to the host fish. Any changes in the environment could alter the face of this parasite-host relationship dramatically and hence the potential pathogenicity of these parasites should, however, not be ignored.Item Open Access Branchial monogenean parasites (Monogenea: Dactylogyridae) of fishes from the Okavango River and Delta, Botswana(University of the Free State, 2002-06) Christison, Kevin William; Van As, J. G.; Basson, LindaEnglish: The Okavango Delta has received much popularity for the host of wildlife that it sustains. More recently it has gained increasing interest for the rich diversity of fish species that occur there. The fishes of the Okavango are also becoming increasingly important as a natural resource attracting revenue to Botswana in the forms of ecotourism and aquaculture and also as an important food source for the local community. The Okavango Delta is a flood driven system and much of the fish distribution throughout the Delta and the timing of certain behavioural activities are dependent on the timing and magnitude of the flood. For the purpose of determining the distribution of fish parasites throughout the system, the distribution of the fish hosts was determined and it was found that fish community structure could be used to distinguish different habitat types within the different ecological regions. Fifty-nine of the expected 68 fish species for the Delta have been collected. These species represent 12 families of which the families Cichlidae and the Cyprinidae are the most abundant, making up about 50 percent of the species collectively. Various parasites have been collected from these fishes of which the monogeneans seem to be the most prevalent and abundant and currently represent approximately 36% of the parasites collected. Most of the monogeneans recorded thus far were representatives of the subclass Polyonchoinea. Of these, all belonged to the families Dactylogyridae and Gyrodactylidae. Of the monogenean parasites infesting the Okavango fishes, the representatives of the family Dactylogyridae were the most diverse. Genera of African dactylogyrids are either endemic to Africa or belong to genera with wider geographical ranges. In general dactylogyrids are host specific and their zoo geographical affinities are therefore linked to the faunistic origin of their hosts. The distribution of dactylogyrid species within Africa is determined by the distribution pattern of their hosts. Twenty-two dactylogyrid species comprising seven genera were recorded, of these 10 species were previously undescribed. This study represents the first records of representatives of the class Monogenea from Botswana and hence the Okavango Delta.Item Open Access Fish myxosporeans from the Okavango Delta, Botswana and the south coast of South Africa(University of the Free State, 2003-12) Reed, Cecile Catharine; Basson, Linda; Van As, Liesl L.; Dykova, IvaEnglish: Myxozoans form a diverse and economically important group of endoparasites that have been intriguing researchers ever since the early1800's. These parasites are notorious, having been associated with the devastating effects many species have shown in aquaculture and fisheries industries throughout the world. Research on both freshwater and marine myxosporeans in Africa is limited to a few countries and has, until recently, been largely neglected in southern Africa. In recognition of the need to investigate the presence of fi sh-infecting myxosporeans in both the freshwater and marine environments of southern Africa, a study was initiated in 1997 investigating the biodiversity of myxosporeans infecting fi shes in two very unique southern African localities. Firstly, the Okavango River and Delta in Botswana contains one of the worlds largest inland deltas composed of about 18 000 km2 waterways. Situated in the middle of the Kalahari Desert, this pristine wetland is the only one of its kind that forms an inland delta and one of the few river systems in the world that is visible from space. The research on myxosporeans infecting marine fi shes was conducted along the Cape south coast of South Africa, which has one of the most diverse marine fauna and flora compositions in the world of which 13 % is endemic. This study aimed to review all existing literature concerning freshwater and marine fish-infecting myxosporeans in Africa, report on the biodiversity and prevalence of fi sh-infecting myxosporeans in the Okavango River and Delta, Botswana, investigate the pathogenic potential of myxosporeans infecting the Okavango fi shes, determine the taxonomic status, species biodiversity and prevalence of myxosporeans infecting fi shes along the Cape south coast, South Africa and investigate the pathogenic potential of myxosporeans infecting intertidal and surf zone fi shes along the Cape south coast of South Afri ca. The examination of 285 8 fi shes representing 14 families and 65 species on several field trips to the Okavango Ri ver and Delta from 1997 to 2001 revealed the presence of 29 different fish infecting myxosporeans representing the genera Henneguya Thelohan, 1892 and Myxobolus Btitschli, 1882. Six of these species have been described as new in three articles prior to this study. Another two new species have been recorded in this thesis, together with the records of 14 miscellaneous species that have never been described before, but require more materi al for the completion of species descriptions. During the course of nine surveys conducted along the Cape south coast of South Africa since March 1998, a total of 410 fishes representing 33 species were examined for parasitic infections. Results from these surveys revealed the presence of 15 different myxosporean species. Three species from the genus Ceratomyxa Thelohan, 1892, one species from the genus Henneguya, two from the genus Myxidium Biltschli, 1882, one species from the genus Myxobolus and one species from the genus Sphaeromyxa Thelohan, 1892 are described in this thesis. Two keys for the identification of both the freshwater, as well as marine and estuarine fish-infecting myxosporeans in Africa are presented as a conclusion to this study. The results obtained from this study have laid the foundation for the continuation of research on these parasites in southern Africa and has provided an insight into the great diversity of myxosporeans infecting southern African fishes.Item Open Access The identification of Diptera of the grave and their succession patterns during winter and summer in central South Africa, with reference to forensic applications(University of the Free State, 2016-01) Van der Merwe, Sylvia Shalomé; Brink, Sonja L.; Basson, LindaEnglish: Forensic entomology is a specialist branch of forensic sciences in which information about insects is used to draw certain conclusions when investigating medico-legal cases involving both humans and wildlife. The primary application of insects collected from a crime scene is to determine the Post-Mortem Interval (PMI). One of the principal cornerstones in the effective application of forensic entomology is the correct identification of species found at a crime scene. The estimation of PMI using succession and developmental data is dependent upon the specific species that were present on a cadaver. The aim of this study was to identify the members of the Diptera that are capable of colonising buried carrion within a Free State grassland area, as well as to compare below ground dipteran data with above ground dipteran succession patterns. The field experiments, conducted in order to determine what species of Diptera are capable of reaching buried carrion during winter and summer months, as well as to determine the succession patterns of Diptera on buried remains, were conducted on the west fields of the University of the Free State campus, in central South Africa. The area is characterised by dry mild winters and warmer summers, with occasional rainfall periods. A total of seven pigs (Sus scrofa Linnaeus 1758) were used during each season, which consisted of one above ground control carcass and six separate below ground carcasses buried at 60 cm. Below ground carcasses were left for predetermined periods of time and were excavated on separate occasions over each 120 day trial period to monitor dipteran occurrence, colonisation and dipteran interactions. Members of Diptera were found to colonise carcasses at 60 cm during both winter and summer trials. Higher dipteran species diversity was noted on the buried winter carcasses in comparison to the buried summer carcasses. Four species of Diptera, Megaselia scalaris (Loew 1866) (Phoridae), Conicera tibialis Schmitz 1925 (Phoridae), Muscina stabulans (Fallén 1817) (Muscidae) and Leptocera Olivier 1813 sp. (Sphaeroceridae) were seen to occur on winter carcasses, with first colonisation taking place from day 21 of the winter trial. Three species of the Diptera, M. scalaris, Leptocera sp., and Sarcophaga Meigen 1826, were seen to colonise buried summer carcasses, with first colonisation taking place from day 21 of the summer trial. Dipteran faunal composition on buried carcasses was noted to be different to that of Diptera on above ground carcasses during both the winter and the summer trials. Statistical analysis showed that there was a significant difference between above ground and below ground dipteran faunal similarity. Preservation experiments on immature Diptera of the grave for identification purposes showed that the standard preservation mediums used for insects of forensic importance, such as ethanol solution and formaldehyde solution, are not effective. Preservation of adult samples was successful in 70% ethanol solution. Breeding trials under laboratory conditions proved effective in breeding larval instars found on buried carcasses through to adulthood for identification. Due to the difficulty in preservation of immature individuals of Diptera of the grave, and the ease of breeding larvae of these dipteran species, identifications were done on adult specimens. Adult Diptera were described based on taxonomic criteria, including wing venation, setal hairs and the hypopygium of male phorid specimens, and a simplified identification key was successfully compiled using morphology of the adult Diptera of the grave.Item Open Access Key diagnostic characteristics of the developmental stages of forensically important calliphoridae and sarcophagidae in central South Africa(University of the Free State, 2011-12-15) Brink, Sonja Lindsey; Van der Linde, Theuns C. de K.; Basson, Linda; Van Wyk, Pieter W. J.English: The first insects attracted to a decomposing body are usually representatives of the Diptera, in particular members of the families Calliphoridae (blow flies) and Sarcophagidae (flesh flies). These flies will deposit their eggs (or often larvae in the case of sarcophagids) on the body, within a few hours after death, depending on environmental conditions. The immature stages will complete their developmental cycle on and around the body. As a consequence, these insects are of great importance in forensic entomology; the main area of application being the determination of the postmortem interval (PMI). One of the key pieces of information needed to calculate the PMI is the correct species identification of the immature stages. The aim of this study was to provide diagnostic descriptions for the immature stages of forensically important calliphorids and sarcophagids in central South Africa. Forensically important calliphorids prevalent in this region are Lucilia cuprina (Wiedemann), Lucilia sericata (Meigen), Chrysomya chloropyga (Wiedemann), Chrysomya marginalis (Wiedemann), Chrysomya albiceps (Wiedemann) and Calliphora vicina Robineau-Desvoidy. The sarcophagid prevalent in the region is Sarcophaga cruentata Meigen. A range of characteristics was evaluated by means of light and scanning electron microscopy and the most pertinent of these were identified for diagnostic purposes. The eggs were evaluated in terms of nine characteristics; six of which were of no diagnostic use, while three could be used to identify some of the species. The eggs of C. chloropyga and C. albiceps were indistinguishable from each other. Twelve features were identified for their possible diagnostic value in larvae. In first instar larvae five of these characteristics were of no diagnostic value, while six were useful to identify some of the species. All species could, however, be identified with the aid of the cephalopharyngeal skeleton. For second instar larvae, four of the characteristics were of no diagnostic use, but seven were useful to identify some of the species. All the species could be identified using the cephalopharyngeal skeleton. In the third instar larvae four characteristics were of no diagnostic use, but by using three other characteristics some of the species could be identified. All the species could be identified by means of five morphological characteristics (labrum, cephalopharyngeal skeleton, posterior spiracles, spiracular plate and anal area). Seven characteristics were identified for their possible diagnostic values in puparia. Five of these characteristics were useful to identify some of the species, but all the species could be identified with the aid of two of the characteristics (frontal field and bubble membrane). The ultimate aim of the study was to construct keys for use during the identification of specimens found at the crime scene. The keys that were constructed not only mapped out the pertinent diagnostic characteristics, but also considered what characteristics could be combined when a specimen was viewed from a specific angle. Since specimens often reach the forensic laboratory in less than optimal condition, it is essential that a wide range of characteristics and keys be available during identification. This will also enable the forensic entomologist to give priority to specimen preparation and the method of observation when rapid analysis is needed or where very few good specimens are available for identification. With these tools (descriptive diagnostic characteristics and keys) the identification of immature stages of calliphorids and sarcophagids found at the crime scene should be an uncomplicated exercise.Item Open Access Myxosporean parasites (Myxozoa: Myxosporea) infecting fishes in the Okavango River system, Botswana(University of the Free State, 2000-06) Reed, Cecile Catharine; Basson, Linda; Van As, Liesl L.English: The Class Myxosporea Butschli, 1882 comprises an enormous group of spore forming obligatory parasites that are able to infect any organ of the hosts in which they are found. Myxosporeans mostly parasitise fish and to date there are more than 1300 species known from fishes throughout the world. In Africa, approximately 84 species have been described from primarily freshwater fish. Research on myxosporeans in southern Africa is very limited, with only a few publications appearing from the coast of South Africa during the early 20th century. In Botswana no research has ever been conducted on myxosporean parasites infecting fishes. Botswana contains one of the worlds largest inland delta systems formed by the Okavango River, which flows in a southeasterly direction from Angola. Knowledge on the fishes as well as their parasites is essential for the well being of a unique body of water such as this. Since myxosporean parasites of fish hold the potential to be pathogenic to their hosts and have been known to cause serious economical losses in aquaculture industries throughout the world, it is thus essential to determine the distribution and biodiversity of these parasites in the Okavango River and Delta in Botswana. The main aims of this project were to investigate the available literature regarding African myxosporeans, compile a database of species infecting freshwater fishes in Africa and to investigate the taxonomic status, species biodiversity and prevalence of myxosporeans infecting fishes in the Okavango River and Delta in Botswana. Fieldwork for this project was conducted in June and July 1998 and 1999 in the Okavango and a total of 275 fishes belonging to 31 species from nine different families were examined for the presence of myxosporean parasites. Five myxosporeans from the genus Henneguya Thélohan, 1892 were collected from four different fish hosts. Only one of these was identified as a known species and was described in this dissertation. A comprehensive morphological description of the four unknown species was also provided. Eight myxosporeans from the genus Myxobolus Butschli, 1882 were also found infecting nine different fish hosts, of which four were identified as known species and described. Detailed descriptions of the four unknown species were provided. It was also found that some fish species showed very high gill infections of these parasites, which may cause some form of respiratory deficiency. This current investigation into myxosporean parasites infecting fishes in the Okavango River System in Botswana provided new insight into the distribution of myxosporeans in southern Africa and has also opened the door for future research in this unique group.Item Open Access Reproductive processes of scyphidiid peritrichs associated with limpet and haliotid hosts along the coast of South Africa(University of the Free State, 2002-11) Peters, Helene; Basson, Linda; Van As, Liesl L.English: During the early 19th century a lot of progress was made in clarifying reproduction patterns and cycles in the kingdom Protozoa Goldfuss, 1818. During the first half of the 20th century various scientists studied the reproductive processes of peritrichs and made valuable contributions. While thousands of recent papers exist on reproduction of ciliates, not much work has been done on epibiontic peritrichs. In this study the processes of binary fission, telotroch formation and conjugation are described for Mantoscyphidia branchi Van As, Basson & Van As, 1998, M. marioni Van As, Basson & Van As, 1998, M. midae Botes, Basson & Van As, 2001 and M. spadiceae Botes, Basson & Van As, 2001. It was also determined whether binary fission, telotroch formation and conjugation occur in a new species of Ellbiophrya Peters, Van As, Basson & Van As, in prep. Haliotids were collected from 1997 to 2002 at the De Hoop Nature Reserve on the south coast of South Africa and were also obtained from the Danger Point Abalone Farm near Gansbaai, and the Abagold Farm in Hermanus. Limpets were collected from 1993 to 2002 from the Goukamma Nature Reserve, De Hoop Nature Reserve and Keurboom Beach on the south coast; Mc Dougall's Bay and the Olifants River Mouth on the west coast; Bazley and at the rocky shores of Lake St. Lucia on the east coast of South Africa; and on the east coast of Marion Island at Boulder Beach which is situated in the southern Indian Ocean. Live symbiont specimens undergoing reproduction were observed with light microscopy and photomicrographs were taken of the various stages of binary fission, conjugation and telotroch formation. Mayer's, Harris' and Heidenhain's Iron Hematoxylin were used to stain the nuclear apparatus. The details of the infundibulum were studied by staining Bouin's fixed smears with protargol. Gills were also examined using scanning electron microscopy. Binary fission was mostly observed in M. spadiceae and also occurred earlier in M. spadiceae than in M. branchi and M. midae populations. The formation of telotrochs was mostly observed in populations of M. branchi and M. spadiceae. Throughout this study it was uncertain whether binary fission always has to occur before a telotroch can develop, or whether binary fission follows telotroch formation. Conjugation was mostly observed in populations of M. branchi and M. midae. In the Ellobiophrya species conjugation was also observed and this is the first record of conjugation in the genus Ellobiophrya (Chatton & Lwoff, 1923). It would be possible to study all these processes in detail if a suitable medium could be cultured in future.Item Open Access Sessiline ciliophorans associated with Haliotis species (Mollusca: Archaeogastropoda) from the South Coast of South Afica(University of the Free State, 1999-06) Botes, Heléne; Basson, Linda; Van As, Liesl L.English: Abalone, locally known as perlemoen, are herbivorous marine gastropods with all species in one genus, Haliotis Linneaus, 1758. Abalone have been commercially exploited since ancient times. Along the southern African coast, the genus Haliotis comprises six endemic species. Surveys carried out from 1995 to 1999 at the De Hoop Nature Reserve along the south coast of South Africa, revealed the presence of scyphidiid peritrichs, of the genus Mantoscyphidia Jankowski, 1980, occurring in abundance on the gills of Haliotis spadicea Donovan, 1808 and H. midae Linnaeus, 1758. These were described as two new species, i.e. M spadiceae sp. nov. and M midae sp. nov. The mantoscyphidians in turn hosted ellobiophryids of the genus Caliperia Laird, 1953, which was also described as a new species, Caliperia perlemoenae sp. nov., occurring on both mantoscyphidian species. During the study a perlemoen aquaculture facility, Danger Point Abalone Farm, was also visited, specimens of H. midae were examined and found to harbour the same species of scyphidiid peritrich and caliperid than H. midae collected from the De Hoop Nature Reserve. In the present study, severe infections of redial, cercarial and metacercarial stages and a few adult specimens of a digenean trematode were also found in the digestive gland of Haliotis spadicea as well as on the gill filaments. In order to elucidate the symbiont/host associations field experiments and histopathological examinations were carried out. These led to the conclusions that the host/scyphidiid peritrich associations are most likely not parasitic. In the case of the mantoscyphidianlcaliperid association, no clear evidence was found that the caliperids are pathogenic to their mantoscyphidian hosts. On the other hand, the trematodes could be potential pathogens since they can cause tissue destruction and affect the reproductive organs in the host.