Gyrodactylus serrai n. sp. (Gyrodactylidae), from the Near-Threatened Clanwilliam Sawfin, Cheilobarbus serra (Peters) (Cyprinidae, Smilogastrinae), in the Cape Fold Ecoregion, South Africa

Syst Parasitol (2024) 101:67 https://doi.org/10.1007/s11230-024-10186-9 Gyrodactylus serrai n. sp. (Gyrodactylidae), from the Near‑Threatened Clanwilliam Sawfin, Cheilobarbus serra (Peters) (Cyprinidae, Smilogastrinae), in the Cape Fold Ecoregion, South Africa Iva Přikrylová · Marliese Truter Albert Chakona · Nico J. Smit · Wilmien J. Luus‑Powell · Received: 20 May 2024 / Accepted: 27 August 2024 © The Author(s) 2024 Abstract A new species of Gyrodactylus is described from the gills of the near-threatened Clanwilliam sawfin, Cheilobarbus serra (Smiliogastrinae) collected from the Matjies River, Cape Fold Ecoregion, Western Cape Province, South Africa. Morphometry and morphology of the haptoral hard parts (hamuli, bars and marginal hooks) of Gyrodactylus serrai n. sp. differ from the other known species of the genus in the smaller size of hamuli and the shape and size of marginal hooks. Furthermore, ITS rDNA for the new species is unique among available Gyrodactylus spp. data in GenBank. Based on the uncorrected p-distances, Iva Přikrylová and Marliese Truter shared first authorship. I. Přikrylová (*) · W. J. Luus‑Powell DSI‑NRF SARChI Chair (Ecosystem Health), Department of Biodiversity, School of Molecular and Life Sciences, University of Limpopo, Sovenga 0727, South Africa e-mail: I. Přikrylová · M. Truter · N. J. Smit Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa M. Truter · A. Chakona · N. J. Smit NRF-South African Institute for Aquatic Biodiversity (NRF-SAIAB), Makhanda 6140, South Africa A. Chakona Department of Ichthyology and Fisheries Science, Rhodes University, Makhanda 6140, South Africa G. serrai n. sp. is genetically most closely related to Gyrodactylus moroccensis Rahmouni, 2023 and Gyrodactylus pseudomoroccensis Rahmouni, 2023 from two species of Luciobarbus (Barbinae) from northern Africa, with interspecific divergence of 8.7% and 8.8%, respectively. The presence of a median ridge in the terminal part of the ventral bar membrane at G. serrai n. sp. most probably represents a morphological link to the North African Gyrodactylus spp. that suggests a morphogenetic association across the African continent as a result of ancient waterways that facilitated the dispersion of cyprinids and their parasite fauna or an independent evolution event retaining similarities from a common ancestor. The description of Gyrodactylus serrai n. sp. represents only the second species of Gyrodactylus described from an endemic South African cyprinid host, underscoring the need for focused research on this group of fishes to provide a sound understanding of the parasitic communities of these highly threatened and poorly studied hosts. Introduction The Cyprinidae is a highly diverse family of freshwater fishes with more than 1700 recognised species in 10 subfamilies and 158 genera (Fricke et al., 2023). Southern Africa boasts more than 80 cyprinid species of which 56 are known from the rivers of South Africa (Skelton, 2001). Recent Vol.: (0123456789) 67 Page 2 of 16 taxonomic studies, however, indicate that the cyprinid diversity may be higher than currently thought (Skelton et al., 2018; Chakona et al., 2022). This is evident in South Africa’s Cape Fold Ecoregion (CFE) where there are currently 18 endemic cyprinid species, with an additional six candidate species awaiting formal taxonomic description (Skelton, 2001; Chakona et al., 2013, 2014, 2022; Skelton et al., 2018). Despite the growing discovery of higher cyprinoid diversity, limited attention has been given to studying the parasite communities associated with these fishes, in particular, those endemic to South African rivers (see Acosta et al., 2022). One example is the genus Cheilobarbus Smith which represents one of 33 genera of the subfamily Smiliogastrinae and contains only two valid species, the endangered Cheilobarbus capensis (Smith) and the near-threatened Cheilobarbus serra (Peters), both endemic to the CFE (Impson et al., 2017; Chakona et al., 2022). The subfamily Smiliogastrinae is a monophyletic clade of both diploid and tetraploid barbs consisting of 11 genera and 268 species endemic to Africa, and 19 genera with around 211 species distributed across Asia (Fricke et al. 2023). Within the Smiliogastrinae, the African representatives form a monophyletic lineage and is the sister group of the Asian genus Systomus McClelland (Yang et al., 2015; Ren and Mayden, 2016; Schedel et al., 2022). Both the African barbs and Systomus are nested among Asian representatives, making it likely that the Smiliogastrinae originated in Asia and dispersed into Africa in a “single” dispersal event with subsequent diversification on the continent (Yang et al., 2015; Ren and Mayden, 2016; Lavoué, 2020). Ren and Mayden (2016) estimated the crown age of the Smiliogastrinae as 37.4–31.2 Mya and the time of divergence between Systomus and the African barbs as 26.4 Mya (95% CI 28.4–20.5 Mya). Monopisthocotylans of Gyrodactylus von Nordmann, 1832 are fish parasites with a global distribution parasitising a wide host range spanning many fish families (Harris et al., 2004; Paladini et al., 2011; Dos Santos et al., 2019; Lebedeva et al., 2021). Two decades ago, 409 valid species of the genus were confirmed (Harris et al., 2004) but the known diversity of the genus is thought to be over 500 species, with more than 80 Gyrodactylus spp. described in the last decade (PubMed search November 2023). Compared to the worldwide Vol:. (1234567890) Syst Parasitol (2024) 101:67 diversity of Gyrodactylus, the number of known African species (44) is still low, with only six species reported from cyprinid hosts distributed across the African continent [i.e., G. ivindoensis Price & Gery, 1968 (Gabon); G. kyogae Paperna, 1973 (Uganda); G. nyingiae Shigoley et al., 2023 (Morocco); G. moroccensis Rahmouni, 2023 (Morocco); G. paludinosus Truter et al., 2022 (South Africa); G. pseudomoroccensis Rahmouni, 2023 (Morocco)]. The Moroccan species, G. nyingiae, G. moroccensis, and G. pseudomoroccensis, are parasites of species of Luciobarbus Heckel (Barbinae) while the remaining three Gyrodactylus spp. infect various species of Enteromius Cope (Smiliogastrinae). In comparison to the rest of the world, the gyrodactylid diversity in South Africa is rather low, with only eight recognised species of Gyrodactylus. Two of these species are known from marine hosts and six occur in freshwater environments with only two species reported from cyprinid hosts (Truter et al., 2022; Maduenyane et al., 2023). Gyrodactylus eyipayipi Vaughan et al., 2010 and G. molweni Christison et al., 2021 were found on marine fishes, Sygnathus acus Linnaeus and Chelon richardsonii (Smith) respectively, along the coast of the Western Cape Province (Vaughan et al., 2010; Christison et al., 2021). The freshwater species described from South Africa are G. paludonisus from Enteromius paludinosus (Peters), G. tra (...truncated)