Checklist of acanthocephalan parasites of South Africa

Abstract Twenty-one species of acanthocephalans, representative of thirteen genera from ten families of seven orders and three classes, are included in this updated checklist of acanthocephalans in South Africa. Although South Africa appears to have a less diverse acanthocephalan fauna compared to some other countries such as Iran in Asia, or Brazil in South America, this is probably an artefact of fewer parasitological surveys.


Introduction
South Africa's landscape is the third most biologically diverse in the world with 6% of the world's mammal species, 8% of bird species and 5% of reptile species of which many are endemic (da Silva and Willows-Munro 2016). In regard to invertebrates, only 36,803 species are listed for Africa, and 12,098 for South Africa (Hamer 2010). It is said that in South African habitats, there are many undiscovered and undescribed animal species, especially invertebrates. It is estimated that as many as 80,000 South African animal species remain to be discovered or described, and most of these animals are invertebrates (Hamer 2013).
The most comprehensive checklist of helminth parasites of Africa was compiled for freshwater fishes by Khalil (1971) and updated by Khalil and Polling (1997). It included very few records of acanthocephalans considering the total number of freshwater fish species present in the continent. The updated list (Khalil and Polling 1997) comprised 568 adult helminth parasites of which only 21 species are acanthocephalans. These records were compiled from 359 species of African freshwater fishes (assigned to 89 genera belonging to 32 families) of an estimated 3000 existing inland fish species (Khalil and Polling 1997). These examples illustrate the lack of knowledge of the helminth fauna of the wildlife of the African continent in general and in South Africa in particular. This is the first checklist of acanthocephalans of South Africa and the aim is to provide a comprehensive record of all the previously reported species of Acanthocephala occurring in South African hosts as well as new records from our on-going research on parasites of wildlife, while simultaneously demonstrating the need for more extensive parasitological surveys.

Materials and methods
Data were obtained from two sources, published records and our own ongoing studies on the Acanthocephala of South African wildlife. These data are presented in two parts. In the first part parasites are listed systematically, with families, genera, and species in alphabetical order. The scientific name, including any synonyms, followed by the scientific and common name of the host, the locality in which the parasite was reported and museum (location) of type specimens where known. In the second part, the hosts are listed systematically by their scientific names and parasite records from each host are given together with locality and reference. The records without references are those of our ongoing study that are being reported here for the first time.
Classification of the Acanthocephala follows Amin (2013). For the hosts, fish taxonomy is based on Skelton (2001Skelton ( , 2016 and Fishbase (Froese and Pauly 2016), bird taxonomy is based on Clements et al. (2016) and mammal taxonomy on Wilson and Reader (2005) and Apps (2012).
Abbreviations for museums are: Acanthocephalan specimens from our ongoing wildlife parasitology projects were mostly collected from roadkill animals, museum collections, hunting/culling surveys and other research permits received for a limited number of specimens through the Limpopo Department of Economic Development, Environment and Tourism (LEDET) (permit number CPM004961 and ZA/LP/HO/3370 for freshwater fish research, 001-CPM403-00012 and ZA/LP/HO/3448 for frogs, ZA/LP/HO/3432 for rodents and ZA/LP/87586 for roadkills).

BMNH
Acanthocephalans from freshly dead animals were placed in tap water and refrigerated for a few hours to one day until the proboscis was everted and then fixed and stored in 70% ethanol until studied. Acanthocephalans from frozen hosts were fixed and stored in 70% ethanol. Some specimens were prepared for examination by staining in Mayer's acid carmine, destained in HCl in 70% ethanol, dehydrated through increasing concentrations of ethanol, cleared in xylene, and mounted as whole worms in Canada balsam. Other worms were examined as temporary mounts following clearing in lactophenol or beechwood creosote.
A total of 102 species of birds (151 individuals), 72 of mammals (420 individuals), 9 of reptiles (18 individuals) and 42 (1050 individuals) of fishes were examined for this study (details in Table 1).

Results and discussion
A total of twenty-one species of acanthocephalans, from thirteen genera from ten families of seven orders, comprise this updated checklist of acanthocephalans in South Africa. Representatives of three of the four classes of acanthocephalans (Amin 2013) have been reported in South Africa, with only the Polyacanthocephala Amin, 1987 not having been recorded yet. The composition of reported acanthocephalan fauna shows that the Polymorphidae is the most represented family with five named species parasitic in marine fish and wild birds. In South Africa, birds have the highest species richness of acanthocephalans to this date with nine named species (from five genera) and five records only identified to group level, followed by fish with eight named species (from six genera) and two species only identified to genus level, mammals with four named species (from two genera) and three species only identified to genus level and finally reptiles with a single species only identified to group level. No acanthocephalans have been reported in amphibians to date. During the current study 110 frog specimens belonging to 19 species were examined but none harboured any acanthocephalans. However, this forms a small part of the entire amphibian fauna of the country which includes 128 described frog species (Frost 2018).
Only a small fraction of the vertebrate fauna of South Africa has been surveyed for acanthocephalans and we expect that in future additional acanthocephalan species will be discovered and described. For example it is estimated that many of South Africa's marine fish parasites have yet to be discovered (Smit and Hadfield 2015). South Africa has an extremely rich biodiversity (Huntley et al. 2005), with nearly 8% of the world's known species of birds, 6% of mammal species and 5% of reptile species (Driver et al. 2012). Therefore we might expect a more diverse acanthocephalan fauna compared to that of Brazil which has 23 genera and 34 species (from only 119 fish species) (Santos et al. 2008) or Iran with 30 described species (Tavakol et al. 2015). The lower species richness reported for South Africa probably reflects sampling effort rather than the true diversity of the acanthocephalan fauna. Until more data are available it will not be possible to determine the true species richness of the South African acanthocephalan assemblage.