Laboratory work was conducted to elucidate the life cycle of the South African gnathiid isopod, Gnathia africana Barnard, 1914. The natural fish hosts of this temporary parasite, the super klipfish Clinus superciliosus (Linnaeus, 1758), were exposed to gnathiid larvae in the laboratory. It was found that G. africana has three larval stages, consisting of three unfed (zuphea) and three fed (praniza) stages. First-, second- and third-stage zuphea larvae took an average of 2 h 18 min, 2 h 43 min and 10 h 8 min respectively to complete their feeding and the first- and second-stage praniza moulted at 8 and 10 days respectively into the next zuphea stage. Three to six days after its last blood meal, the sex of the third and final praniza stage could be determined by the presence of either a testis or two ovaries in the dorsal pereon. Male larvae moulted into adult males between 8 and 10 days post feeding. Female larvae moulted at approximately 17 days into adult females. Fertilisation of the eggs by the male took place within 24 hours of completion of the female moult. The development of the embryos and subsequent release of the young larvae between 15 and 23 days post fertilisation completed the cycle. This entire cycle took approximately 62 days in water temperatures of 20-25°C.
South African clinids are a major component of the temperate intertidal regions that are also known to participate in life cycles and transmission of several groups of parasites. However, the knowledge of trematode diversity of these fishes is incomplete. In this study, two species of Clinus Cuvier, the super klipfish Clinus superciliosus (Linnaeus) and the bluntnose klipfish Clinus cottoides Valenciennes, were collected from six localities along the South African coast and examined for the presence of trematodes. Metacercariae of Cardiocephaloides Sudarikov, 1959 were found in the eye vitreous humour and brain of C. superciliosus and in the eye vitreous humour of C. cottoides. Detailed analyses integrating morphological and molecular sequence data (28S rDNA, ITS2 rDNA-region, and COI mtDNA) revealed that these belong to two species, Cardiocephaloides physalis (Lutz, 1926) and an unknown species of Cardiocephaloides. This study provides the first report of clinid fishes serving as intermediate hosts for trematodes, reveals that the diversity of Cardiocephaloides in South Africa is higher than previously recorded, and highlights the need for further research to elucidate the life cycles of these trematode species. The broad geographical distribution of Cardiocephaloides spp. was confirmed in the present study based on molecular sequence data. The host-parasite interactions between clinid fishes and metacercariae of Cardiocephaloides are yet to be explored.
Dactylogyrus Diesing, 1850 is the most species-rich genus in Platyhelminthes, with over 900 documented species, that are mostly strictly specific to freshwater cyprinoids. The morphological Dactylogyrus groups afrobarbae-type, carpathicus-type, pseudoanchoratus-type, and varicorhini-type are known to occur in Africa. This study describes a new species of Dactylogyrus of the varicorhini-type from the gills of the endemic smallmouth yellowfish Labeobarbus aeneus (Burchell) from the Vaal River, Free State Province, South Africa. Dactylogyrus matlopong sp. n. is unique among its varicorhini-type congeners mainly by the accessory piece of the male copulatory complex that presents a hook-shaped subunit with defined round base not reaching the male copulatory organ, combined with the presence of a conspicuous medial projection on the anterior margin of the ventral bar. Sequences of the partial 28S and 18S rRNA genes, together with entire ITS1 region, were generated for the first time for a species of Dactylogyrus from South Africa. Concatenated phylogenetic analyses of selected Dactylogyrus spp. showed that these parasites group according to their morphological types.
The viviparous gyrodactylid genus Macrogyrodactylus Malmberg, 1957 is endemic to Africa, composed of nine species from hosts of four freshwater fish families, including catfishes (Siluriformes: Clariidae). Three species, Macrogyrodactylus clarii Gussev, 1961; M. congolensis (Prudhoe, 1957) and M. karibae Douëllou et Chishawa, 1995, are primarily known to parasitise the African sharptooth catfish Clarias gariepinus (Burchell) in various African countries. From November 2017 to September 2019, a total of 184 individuals of C. gariepinus were collected from selected localities in southern Africa and their skin, fins and gills were surveyed for monogeneans. Three species of Macrogyrodactylus (M. clarii, M. congolensis and M. karibae) were found parasitising C. gariepinus from five localities in South Africa and Zambia. Overall prevalence was 50% to 100% with intensities of up to 109 parasites per host individual. New locality records in southern Africa, morphological observations and additional molecular data on the complete Internal Transcriber Spacer (ITS-1-5.8S-ITS-2) regions of the rDNA gene for the three gyrodactylid species are presented in this study.
Blood smears prepared from the peripheral blood of 20 wild caught Amietia quecketti (Boulenger) from the North-West University Botanical Gardens, North West Province, South Africa, were examined for the presence of haemogregarines. A haemogregarine species comparative in morphology, host and geographical locality to that of Haemogregarina theileri Laveran, 1905 was detected. The original description of H. theileri was based solely on frog peripheral blood gamont stages. Later, further parasite stages, including trophozoites and merogonic liver stages, were recorded in a related Amietia sp. from equatorial Africa. This species was originally classified as a member of the genus Haemogregarina Danilewsky, 1885, but due to the close life cycle and morphological resemblance to those of Hepatozoon species, H. theileri was later transferred from Haemogregarina to Hepatozoon Miller, 1908. In the present study, meront and merozoite stages not described before, along with previously observed trophozoite, immature and mature gamont stages, are described from the peripheral blood of hosts. In addition, comparative phylogenetic analysis of the partial 18S rDNA sequence of Hepatozoon theileri to those of other haemogregarine species, including those of species of Hepatozoon and a Haemogregarina, support the taxonomic transfer of H. theileri to Hepatozoon, nesting H. theileri within a clade comprising species parasitising other amphibians. This is the first molecular and phylogenetic analysis of an African anuran species of Hepatozoon.
A redescription of the female of the temporary fish parasite, Gnathia africana Barnard, 1914 is provided from specimens reared from final-stage G. africana praniza larvae collected from their intertidal fish hosts along the south coast of southern Africa. It differs from other known gnathiid females in the shape of the frontal border and the number and basic form of pylopod articles. This redescription aims to establish a format for future descriptions and redescriptions of gnathiid females.
Haemogregarina bigemina Laveran et Mesnil, 1901 was examined in marine fishes and the gnathiid isopod, Gnathia africana Barnard, 1914 in South Africa. Its development in fishes was similar to that described previously for this species. Gnathiids taken from fishes with H. bigemina, and prepared sequentially over 28 days post feeding (d.p.f.), contained stages of syzygy, immature and mature oocysts, sporozoites and merozoites of at least three types. Sporozoites, often five in number, formed from each oocyst from 9 d.p.f. First-generation merozoites appeared in small numbers at 11 d.p.f., arising from small, rounded meronts. Mature, second-generation merozoites appeared in large clusters within gut tissue at 18 d.p.f. They were presumed to arise from fan-shaped meronts, first observed at 11 d.p.f. Third-generation merozoites were the shortest, and resulted from binary fission of meronts, derived from second-generation merozoites. Gnathiids taken from sponges within rock pools contained only gamonts and immature oocysts. It is concluded that the development of H. bigemina in its arthropod host illustrates an affinity with Hemolivia and one species of Hepatozoon. However, the absence of sporokinetes and sporocysts also distances it from these genera, and from Karyolysus. Furthermore, H. bigemina produces fewer sporozoites than Cyrilia and Desseria, although, as in Desseria, Haemogregarina (sensu stricto) and Babesiosoma, post-sporogonic production of merozoites occurs in the invertebrate host. The presence of intraerythrocytic binary fission in its fish host means that H. bigemina is not a Desseria. Overall it most closely resembles Haemogregarina (sensu stricto) in its development, although the match is not exact.