Folia Parasitologica 50[2] 135-142 (2003) | DOI: 10.14411/fp.2003.024

Life cycle of the temporary fish parasite, Gnathia africana (Crustacea: Isopoda: Gnathiidae)

Nico J. Smit^1,3, Linda Basson², Jo G. Van As²

¹ School of Life Sciences, Kingston University, Penrhyn Road, Kingston upon Thames, Surrey, KT1 2EE, UK

² Department of Zoology and Entomology, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa

³ Present address: Department of Zoology, University of Cape Town, Private Bag, Rondebosch, 7701, South Africa

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.

Keywords: Isopoda, Gnathiidae, Gnathia africana, life cycle, fish parasite

Received: May 1, 2002; Accepted: January 17, 2003; Published: June 1, 2003  Show citation