Platyhelminthes, Minot, 1876

Smit, Nico J., Malherbe, Wynand & Hadfield, Kerry A., 2017, Alien freshwater fish parasites from South Africa: Diversity, distribution, status and the way forward, International Journal for Parasitology: Parasites and Wildlife 6 (3), pp. 386-401 : 393

2.2. Phylum Platyhelminthes

2.2.1. Schyzocotyle (Bothriocephalus) acheilognathi

It has been well documented that the Asian tapeworm, S. acheilognathi , was most likely first introduced during 1975 into South Africa with its native host, the grass carp Ctenopharyngodon idella Valenciennes, 1844 ( Boomker et al., 1980; Bertasso and Avenant-Oldewage, 2005; Stadtlander et al., 2011). Following its introduction, it successfully established itself in the common carp, Cyprinus carpio (introduced for commercial carp farming). The first published report of this invasive parasite was thus in C. carpio by Boomker et al. (1980), from a commercial fish farm in the Komatipoort area, Mpumalanga Province of South Africa (Table 1, Fig.1D ). As S. acheilognathi appears to not be host specific both on an intermediate or definitive host level, this parasite quickly spilled over to native hosts across South Africa when C. carpio was introduced for aquaculture and recreational angling purposes and C. idella for controlling aquatic weeds ( Stadtlander et al., 2011; Ellender and Weyl, 2014). The first record of this species as a co-invader following spillover was that of Brandt et al. (1981) reporting it parasitising the Vaal-Orange largemouth yellowfish, Labeobarbus kimberleyensis Gilchrist and Thompson, 1913 , collected from the Vaal Dam in the Vaal River ( Fig. 1D ). In the same year, Van As et al. (1981) reported another spillover event, this time in Boskop Dam, Mooi River, with the three-spot barb, Enteromius (Barbus) trimaculatus , as the infected host ( Fig. 1D ). Since these first reports, S. acheilognathi has been reported from at least 10 native hosts (Table 1) from six rivers ( Fig. 1D ) in South Africa ( Mashego, 1982; Barkhuizen, 1991; Schramm, 1992; Retief et al., 2007; Stadtlander et al., 2011; Kuchta et al., 2012; Swanepoel, 2015), making it one of the most widespread co-invasive parasites reported in South Africa.

The pathological effects of S. acheilognathi on native hosts in aquaculture conditions, as well as its threat to wild populations, have been well documented globally ( Dove et al., 1997; Salgado-Maldonado and Pineda-Ĺopez, 2003; Pullen et al., 2009). Howev- er, research in South Africa has mainly focussed on its distribution, ecology, and potential use as bioindicators of metal pollution ( Bertasso and Avenant-Oldewage, 2005; Retief et al., 2007; Degger and Avenant-Oldewage, 2009), with a paucity of data on its population and community level impact on threatened native species. Future studies should specifically focus on these impacts and on regions of high endemicity, such as the Cape Floristic Region of the southern and southwestern Cape Province where the largest percentage of South Africa's threatened freshwater fishes occur.

Figures

Fig. 1. Maps indicating the South African distribution records for (A) Ichthyophthirius multifiliis Fouquet, 1876; (B) Apiosoma piscicola (Blanchard, 1885); (C) Chilodonella hexasticha (Kiernik, 1909) and Chilodonella piscicola (Zacharias, 1894); (D) Schyzocotyle (Bothriocephalus) acheilognathi (Yamaguti, 1934).