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 : 395-397

3.3. Phylum Platyhelminthes

3.3.1. Atractolytocestus huronensis

One of the most recent reports of a co-introduced parasite from South Africa is that of the cestode A. huronensi . Scholz et al. (2015) reported this tapeworm from the intestine of C. carpio from four localities in the Limpopo Province of South Africa (Table 1, Fig. 3B ). Their paper was also the first to include morphological and molecular confirmation of the identity of the introduced parasite. Although Scholz et al.'s (2015) report on this co-introduction is recent, the co-introduction of A. huronensi into South Africa might not be. During parasitological surveys conducted between 2013 and 2016 by the authors of this review in the Vaal River (North West Province), as well as in the Riet River (Northern Cape Province), A. huronensi specimens were collected from C. carpio at both sites (Smit unpublished records). These records are now included here (Table 1, Fig. 3A ) and demonstrate a much wider distribution in different river systems than originally thought, and thus an unlikely pattern usually seen in a recent introduction. We concur with Scholz et al. (2015) that future work on this tapeworm should include phylogeographic studies employing molecular markers to reveal the source of introduction of this co-introduced parasite.

3.3.2. Acolpenteron ureteroecetes

The first record of a co-introduced parasite into South Africa is, according to our records, that of Du Plessis (1948), who reported the presence of the monogenean A. ureteroecetes in the urethras of three bass species, Micropterus dolomieu (Lacep̀ede, 1802), Micropterus punctulatus (Rafinesque, 1819) , and Micropterus salmoides (Lacep̀ede, 1802), bred in the Jonkershoek Fish Hatchery, Western Cape Province. Although all three species were infected, only M. salmoides had high parasite loads that directly lead to the mortality of large numbers of fingerlings ( Du Plessis, 1948). Mortality of cultured M. salmoides due to A. ureteroecetes infections were more recently reported by Petrie-Hanson (2001) from pond reared fish in Mississippi, USA, confirming Du Plessis' (1948) original observation of A. ureteroecetes ' pathogenicity. The only record of A. ureteroecetes in wild M. salmoides from South Africa is a non-peer reviewed published conference abstract by Matla et al. (2010) reporting a very low infection of this species from the ureterurinary bladder of M. salmoides collected in the Tzaneen Dam, Limpopo Province (Table 1, Fig. 3B ). As the stocking of most of the M. salmoides populations in South Africa was via the Jonkershoek Fish Hatchery ( De Moor and Bruton, 1988), the co-introduction of A. ureteroecetes into the Limpopo Province was most likely from the original Jonkershoek Fish Hatchery stock. Research into the parasites of other populations of M. salmoides will most probably reveal a much wider distribution of A. ureteroecetes in South Africa and warrants further research.

3.3.3. Dactylogyrus extensus , Dactylogyrus minutus and Dactylogyrus lamellatus

The three dactylogyrids, D. extensus , D. minutus , and D. lamellatus are well documented known co-invaders, with their widely introduced host, C. carpio , for the former two and the grass carp, Ctenopharyngodon idella for the latter (Dove and Ernst, 1998; Yang et al., 2016). Crafford et al. (2014a) recorded all three of these species from their respective wild caught introduced hosts from the Vaal Dam in the Vaal River, South Africa (Table 1, Fig. 3C ), with Dactylogyrus extensus and D. minutus collected from C. carpio , and D lamellatus from C. idella . With representatives of Dactylogyrus Diesing, 1850 considered to be very host specific, the chances of host switching to native fish by these co-invaders are limited (Dove and Ernst, 1998; Simkováet al., 2001). This is further supported by the work of Crafford et al. (2012; 2014a,b) on the monegeneans of fishes from the Vaal Dam, who did not report any spillover of these introduced Dactylogyrus species onto any of the native hosts studied.

3.3.4. Gyrodactylus kherulensis

The gyrodactylid G. kherulensis is a parasite of the common as well as the koi carp, C. carpio koi . Similar to the dactylogyrids reported above, G. kherulensis has also been co-introduced worldwide due to the popularity of its natural host as an aquaculture and ornamental species. The first report of G. kherulensis in South Africa was in a non-peer reviewed published conference abstract by Maseng et al. (2010). These authors collected G. kherulensis from commercially bought, as well as wild caught, C. carpio in the Western Cape Province of South Africa (Table 1, Fig. 3D ). Recently Crafford et al. (2014a) found a total of three G. kherulensis specimens on the body surface of a single C. carpio , collected from the Vaal Dam in the Vaal River (Table 1, Fig. 3D ), confirming its status as a co-introduced parasite in South Africa.

3.3.5. Ancyrocephalid monogeneans of largemouth bass, Micropterus salmoides

As part of this special issue on invasive parasites, Truter et al. (2017) provided the first peer reviewed published record of five ancyrocephalid monogeneans form largemouth bass, Micropterus salmoides , collected at three localities in South Africa. In that paper the authors provide full descriptions as well as distribution records and maps (see Truter et al., 2017), for these species. For completeness of the current review these species, Clavunculus bursatus (Mueller, 1963) , Onchocleidus dispar (Mueller, 1936) , O. furcatus (Mueller, 1937) , O. principalis (Mizelle, 1936) and Syncleithrium fusiformis (Mueller, 1934) are only listed here and not further discussed.

Figures

Fig. 3. Maps indicating the South African distribution records for (A) Atractolytocestus huronensis Anthony, 1958; (B) Acolpenteron ureteroecetes Fischthal and Allison, 1940; (C) Dactylogyrus extensus Mueller and Van Cleave, 1932, Dactylogyrus minutus Kulwiec, 1927 and Dactylogyrus lamellatus Achmerow, 1952; (D) Gyrodactylus kherulensis Ergens, 1974.