A new species of Neoergasilus Yin 1956 (Copepoda: Cyclopoida: Ergasilidae) parasitic on the catfish Clarias gariepinus (Burchell, 1822) (Siluriformes: Clariidae) from South Africa

Syst Parasitol (2024) 101:64 https://doi.org/10.1007/s11230-024-10189-6 A new species of Neoergasilus Yin 1956 (Copepoda: Cyclopoida: Ergasilidae) parasitic on the catfish Clarias gariepinus (Burchell, 1822) (Siluriformes: Clariidae) from South Africa Precious P. Fikiye · Liesl L. Van As · Marliese Truter · Nico J. Smit · Kerry A. Hadfield Received: 6 November 2023 / Accepted: 4 September 2024 © The Author(s) 2024 Abstract Twenty-one specimens of an ergasilid were collected from the gills of the sharptooth catfish, Clarias gariepinus (Burchell), from the Eastern Cape, South Africa. The first leg and antennae morphology conformed to the genus Neoergasilus Yin, 1956. While the invasive Neoergasilus japonicus (Harada, 1930) is the only Neoergasilus species that has been reported from Africa, the combination of several Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/s11230-024-10189-6. P. P. Fikiye · M. Truter · N. J. Smit · K. A. Hadfield (*) Water Research Group, Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa e-mail: P. P. Fikiye e-mail: M. Truter e-mail: N. J. Smit e-mail: L. L. Van As Department of Zoology and Entomology, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa e-mail: M. Truter · N. J. Smit South African Institute for Aquatic Biodiversity, Private Bag 1015, Makhanda 6140, South Africa characteristics, separates the Eastern Cape specimens from N. japonicus and the other eight Neoergasilus congeners. These include an inflated cephalothorax; the presence of an oval dorsal ornamentation anterior to the cephalosome; a spine on the posterodistal margin of the first antennal segment; a cone-like process at the proximal margin of the second antennal segment; a knob-like process on the inner distal margin of the first exopodal segment of leg 1 and two forked spines on the third exopodal segment; leg 4 bearing a 2-segmented exopod and 3-segmented endopod; a single-segmented fifth leg with a seta extending from the base of the pedigerous somite and three unequal setae on its free segment; and a median caudal rami seta with an array of spines. Supporting genetic data were generated using two partial ribosomal RNA genes, 18S and 28S, and one partial mitochondrial DNA gene, COI. The Eastern Cape species is here proposed as new to science and described as Neoergasilus africanus n. sp. (Ergasilidae: Cyclopoida). This is the first Neoergasilus species described from the sharptooth catfish and from the southern hemisphere. Additionally, a key to all the species of this genus is provided. Introduction Members of the family Ergasilidae Burmeister, 1835 occur globally as parasites of freshwater, brackish, and marine fishes. There are currently 30 accepted Vol.: (0123456789) 64 Page 2 of 16 genera in the family (Hadfield, 2019; Walter & Boxshall, 2024a), of which three have been reported from African freshwater fishes, namely: Ergasilus von Nordmann, 1832; Neoergasilus Yin, 1956 (an invasive species); and Paraergasilus Markevich, 1937 (Oldewage & van As, 1988a, b; Berrouk et al., 2018, 2020; Boucenna et al., 2018; Avenant-Oldewage et al., 2023; Fikiye et al., 2023). During parasitological surveys in South Africa, ergasilids were collected from the gills of the North African catfish, known locally as the sharptooth catfish, Clarias gariepinus (Burchell), in the Great Fish River, Eastern Cape, South Africa. This fish species has been translocated to the Great Fish River as a result of the Inter-Basin Water Transfer scheme from the Gariep Dam (Free State, South Africa) (see Cambray & Jubb, 1977). Currently, catfish populations are established in the Great Fish River and serve as hosts to several parasite species (see Truter et al., 2023a). The morphology of the ergasilid species collected from the current study conformed to the characteristics of members in the genus Neoergasilus. Similar to other ergasilid copepods, members of Neoergasilus are found attached to the gills and fins of their hosts (Hayden & Rogers, 1998; Hudson & Bowen, 2002; Alekseev et al., 2021). There are currently nine accepted species of Neoergasilus (Walter & Boxshall, 2024b) described from China (N. longispinosus Yin, 1956); India (N. ferozepurensis Kumari, Khera & Gupta, 1988; N. indicus Vankara & Chikkam, 2010; N. kherai Battish & Brar, 1989; and N. notopteri Kumari, Khera & Gupta, 1988); Korea (N. angustus Kim & Choi, 2003 and N. bullatus Kim & Choi, 2003); Russia (N. squaliobarbi (Dogiel & Akhmerov, 1952) (syn. N. inflatus see Smirnova, 1971)); and Taiwan (N. japonicus (Harada, 1930)). However, N. japonicus is the only species that has been reported from multiple continents including Africa (Berrouk et al., 2018; 2020; Boucenna et al., 2018; Avenant-Oldewage et al., 2023), Asia (Harada, 1930; Urawa et al., 1980; Kumari et al., 2009; HongWei et al., 2010; Nagasawa & Sato, 2016), Europe (Lescher-Moutoué, 1979; Mugridge et al., 1982; Beyer et al., 2005; Vainikka et al., 2009; Alfonso & Belmonte, 2010; Soylu & Soylu, 2012; Kuş & Soylu, 2013; Elsheikha & Beech, 2017; Ondračková et al., 2019; 2021; Kvach et al., 2021; 2023), North America (Hayden & Rogers, 1998; Hudson & Bowen, 2002; Suárez-Morales Vol:. (1234567890) Syst Parasitol (2024) 101:64 & Mercado-Salas, 2013; Truong & Bullard, 2021), and South America (Mendes Marques & Murrieta Morey, 2019). Although the specimens from this study conform to the genus Neoergasilus, they differed morphologically from all other nine species in this genus. Limited genetic data are available for species of this genus. Currently, the only available sequences on GenBank are for N. japonicus for ribosomal RNA genes, 18S and 28S from the Czech Republic (Ondračková et al., 2019; Kvach et al., 2021), South Africa and Japan (Avenant-Oldewage et al., 2023); and the mitochondrial DNA gene, COI, from South Korea (Baek et al., 2016) and the United States of America (Vasquez et al., 2021 supplementary data). There is also a GenBank submission from South Korea for 18S and 28S gene regions, but it is not associated with any peerreviewed article. This study, therefore, aims to characterise a parasitic copepod species morphologically and molecularly from the genus Neoergasilus not previously known to science as well as provide a key for taxon identification in this genus. Materials and methods Sampling Fifteen specimens of C. gariepinus were caught with baited longlines in November 2018 from the Great Fish River, Eastern Cape, South Africa (33°19′49.3″S 26°59′54.2″E) (Fig. 1). Collected fish were examined for parasites attached to the body surface, fins, and gills, and were dissected and screened with the aid of a Zeiss Stemi 305 dissection microscope following standard methods for crustacean parasites as in Dávidová and Smit (2018). Adult female copepods (n = 21) were collected from the gills using fine pain (...truncated)