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2. Life cycle of the temporary fish parasite, Gnathia africana (Crustacea: Isopoda: Gnathiidae)
- Creator:
- Smit, Nico J., Basson, Linda, and Van As, Jo G.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Isopoda, Gnathiidae, Gnathia africana, life cycle, and fish parasite
- Language:
- English
- Description:
- 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.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Redescription of the female of Gnathia africana (Crustacea: Isopoda: Gnathiidae) from southern Africa
- Creator:
- Smit, Nico J., Van As, Jo G., and Basson, Linda
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Gnathiidae, Gnathia africana, female, redescription, taxonomy, and morphology
- Language:
- English
- Description:
- 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.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. The life cycle of Haemogregarina bigemina (Adeleina: Haemogregarinidae) in South African hosts
- Creator:
- Davies, Angela J. and Smit, Nico J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Adeleina, Haemogregarinidae, Haemogregarina bigemina, Gnathia africana, fish parasites, blood parasites, transmission, and life cycle
- Language:
- English
- Description:
- 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.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public