Parasite diversity and community structure of translocated Clarias gariepinus (Burchell) in South Africa: Testing co-introduction, parasite spillback and enemy release hypotheses.

Clarias gariepinus (Burchell) is one of several freshwater fish species that have been translocated beyond its natural geographic range in South Africa. The present study investigated the parasitic communities of two translocated populations (one in the Riviersonderend River, Western Cape and the other from the Great Fish River, Eastern Cape) as well as its native source population from Gariep Dam, Free State. A total of nine, seven, and eight parasitic taxa were found to parasitise various organs of C. gariepinus from the three populations, respectively. The diversity and abundances of parasitic species in the two translocated populations were similar, but distinct community assemblages were observed. Parasite community composition from the Great Fish River was similar to that of the source population from Gariep Dam, whereas the parasitic community from C. gariepinus in the Riviersonderend River was distinct from that of Gariep Dam. This, together with the introduction history into the Western Cape, suggests that translocated C. gariepinus is sourced from various systems across South Africa, or that suitable intermediate hosts are present in the recipient ecosystems to sustain host-specific co-introduced parasitic taxa of C. gariepinus. In total, the resilience of 11 specialist parasite species of C. gariepinus is demonstrated in their persistence upon co-introduction into the two novel environments with their host, and support for the enemy release hypothesis is confirmed in the loss of known parasite taxa in translocated populations. The presence of the co-invasive fish lice Argulus japonicus Thiele, 1900 is reported from C. gariepinus in Gariep Dam and the Asian tapeworm Schyzocotyle acheilognathi (Yamaguti, 1934) was found from translocated C. gariepinus in the Riviersonderend River, Western Cape and lastly, a suspected case of parasite spillback from an unknown native host is reported.

Review of the metazoan parasites of the economically and ecologically important African sharptooth catfish Clarias gariepinus in Africa: Current status and novel records.

One of the most widely distributed African freshwater fish is the African sharptooth catfish Clarias gariepinus (Burchell) that is naturally distributed in 8 of the 10 ichthyofaunal regions of this continent. Clarias gariepinus is a highly valued and cheap staple to local communities and an ideal aquaculture species. Consequently, interest in the parasitic communities of C. gariepinus has increased as parasites may accidentally be ingested by humans when eating uncooked fish or can be introduced into culture systems through fish stocks supplied from local rivers which affect yield, growth, and marketability. This review provides an overview of the ∼107 metazoan parasite species known to parasitise C. gariepinus in Africa and their general life cycles, morphology, paratenic and post-cyclic infections, and the biogeography and validity of records are discussed. A brief overview is included on the application of some of these parasites in environmental studies and their link to human health.

Morphological and molecular characterisation of Alella igillimpethu n. sp. (Copepoda: Siphonostomatoida: Lernaeopodidae) parasitising the southern African endemic intertidal klipfish, Clinus superciliosus.

Lernaeopodidae Milne Edwards, 1840, is an ecological and economically important fish parasite family of copepods (Crustacea: Copepoda), consisting of 48 genera with 334 valid species. To date, approximately 17 genera have been documented from both teleost and elasmobranch hosts from South African marine waters. As part of parasitological surveys targeting parasites of the endemic intertidal klipfish, Clinus superciliosus (Linnaeus) (Clinidae) along the South African coast, a species of Lernaeopodidae was discovered on the gills of this host. Alella igillimpethu n. sp. is described from Clinus superciliosus from Langebaan marina on the west coast of South Africa, with a prevalence of 42.1% and mean intensity of 2.9 (ranging from 1-13). Morphological identification was done using light and scanning electron microscopy and the species description was generated with the aid of DEscription Language for TAxonomy (DELTA) software. The mitochondrial cytochrome c oxidase subunit 1 (COI) region, as well as partial 18S and 28S ribosomal RNA genes confirmed the classification within the family Lernaeopodidae. This is the first report of Lernaeopodidae from C. superciliosus, or in fact any member of Clinidae, as well as the first molecular characterisation of any marine lernaeopodid infecting teleost fish from South Africa. This study contributes valuable genetic and morphological data for this copepod family, as well as new host and distribution records.

High element concentrations are not always equivalent to a stressful environment: differential responses of parasite taxa to natural and anthropogenic stressors.

Environmental parasitology developed as a discipline that addresses the impact of anthropogenic activities related to the occurrence and abundance of parasites, subsequently relating deviations of natural parasite distribution to environmental impact. Metals, often considered pollutants, might occur under natural conditions, where concentrations might be high due to a natural geogenic release rather than anthropogenic activities. We specifically investigated whether naturally occurring high levels of elements might negatively affect the parasite community of the intertidal klipfish, Clinus superciliosus, at different localities along the South African coast. Parasite communities and element concentrations of 55 klipfish (in muscle and liver) were examined. Our results show that parasites can disentangle anthropogenic input of elements from naturally occurring high element concentrations. Acanthocephala, Cestoda and Isopoda were associated with higher concentrations of most elements. Environmental parasitology, applicable to a wide range of systems, is scarcely used on marine ecosystems and can contribute to environmental monitoring programs.

Metazoan parasite diversity of the endemic South African intertidal klipfish, Clinus superciliosus: Factors influencing parasite community composition.

The current trend in marine parasitology research, particularly in South Africa, is to focus on a specific parasite taxon and not on the total parasite community of a specific fish host. However, these records do not always reveal the ecological role of parasites in ecosystems. Thus, the present study aimed to determine which factors influence the parasite community composition of the endemic southern African intertidal klipfish, Clinus superciliosus (n = 75). Metazoan parasites were sampled from four localities (two commercial harbours - west coast; and two relatively pristine localities - southeast coast) along the South African coast. A total of 75 klipfish were examined for parasites, where 30 distinct taxa, representing seven taxonomic groups were found: Acanthocephala (4 taxa), Cestoda (2 taxa), Crustacea (5 taxa), Digenea (11 taxa), Hirudinea (2 taxa), Monogenea (1 taxon) and Nematoda (5 taxa). Results indicated that the main driver of diversity was locality, with the highest diversity on the southeast coast, most likely due to higher water temperatures and upwelling compared to the west coast. The parasite community composition of the klipfish was significantly influenced by water temperature and parasite life cycle. These results emphasise the importance of parasitological surveys including all parasite taxa in hosts from multiple localities and seasons, to better comprehend their ecological role.

 Gnathiapipinde sp. nov. (Crustacea, Isopoda, Gnathiidae), a temporary parasite of the pufferfish, Amblyrhynchoteshonckenii, from temperate southern Africa.

A new species, Gnathiapipinde sp. nov., is described from specimens taken from pufferfish, Amblyrhynchoteshonckenii, at Chintsa and De Hoop Nature Reserve on the southern Indian Ocean coast of South Africa. Gnathiapipinde sp. nov. is characterised by the straight frontal margin, presence of conical superior frontolateral process, a strong and bifid mediofrontal processes, pronounced and pointed supraocular lobes, mandible strongly curved with a dentate blade, and the claviform penes produced more than a third the length of the pereon. A summary and key to the males of all known species of the Gnathiidae from the Temperate Southern African marine realm is provided.

Two new species of branchial fish parasitic isopod of the genus Mothocya Costa, in Hope, 1851 (Isopoda, Cymothoidae) from Nigeria.

The branchial attaching, fish parasitic genus Mothocya Costa, in Hope, 1851 is recorded for the first time from Nigerian brackish waters on Monodactylus sebae (Perciformes: Monodactylidae). Mothocya andoni n. sp. is characterised by a trapezoid-shaped cephalon with a subtruncate rostrum; pereonite 1 anterolateral angles only reaching to the posterior margin of the eyes; particularly large and wide coxa 7 extending to pleonite 4; pereopod 7 with a narrow basis; broadly rounded pleotelson; and uropods extending to the pleotelson posterior margin, with subequal rami. Mothocya powelli n. sp. is characterised by its small size (7 mm); a posteriorly ovoid body shape; cephalon anterior margin truncate; a short pleon with pleotelson lateral margins converging to a narrowly rounded apex; pleonite lateral margins overlapped by pereonite 7; slender uropods that extend to the posterior margin of the pleotelson with the uropodal exopod almost double the length of the endopod.

Description of life stages, molecular characterisation as well as a new host and locality record of Chonopeltis lisikili Van As and Van As (1996) from Phongolo River, South Africa.

Chonopeltis lisikili Van As and Van As, 1996 was original described from the Eastern Caprivi (Namibia) and the Okavango System (Botswana), collected from five Synodontis Cuvier, 1816 (Mochokidae) species. This fish genus is endemic to Africa, with 130 valid species, making it one of the most species-rich and widely distributed mochokid catfish family. During parasitological surveys conducted in the Phongolo River (South Africa), a Chonopeltis Thiele, 1900 species was collected from Synodontis zambezensis Peters, 1852. In total, 21 adult females, four adult males, as well as representatives of the larval developmental stages were found. After morphological comparison, this branchiuran was identified as C. lisikili. This paper provides additional information on body measurements and morphological information of all the life stages of the Phongolo material. Information on Chonopeltis material collected from the Okavango River, Botswana, not yet published is also included as well as the first molecular characterisation of a Chonopeltis species using COI and 18 S rRNA partial sequencing. The endemicity of the host and fish lice necessitates a discussion on the host origin and distribution in more than one river system, particularly referring to host specificity for Chonopeltis species.

Morphological description and molecular characterisation of a new species of Anilocra Leach, 1818 (Crustacea: Isopoda: Cymothoidae) from India.

A fish parasitic isopod recently reported from India as Anilocra leptosoma Bleeker, 1857, was re-examined and morphologically compared to five closely related species: A. capensis Leach, 1818, A. clupei Williams and Bunkley-Williams, 1986, A. leptosoma Bleeker, 1857, A. paulsikkeli Welicky and Smit, 2019 and A. pilchardi Bariche and Trilles, 2006. This species was sequenced and compared to other known Anilocra species based on mitochondrial cytochrome c oxidase subunit I (COI) gene fragments. Both morphological and molecular data corroborate that the Anilocra species parasitising the clupeid fish Tenualosa toli (Valenciennes, 1847) from India should be recognised as a new species, and we describe Anilocra grandmaae n. sp. based on the holotype and paratype females. The key characters of A. grandmaae n. sp. include the body being less than 4.0 times as long as wide; antennula article 3 anterodistal margin expanded, 1.2-1.4 times as wide as long; pleonite 1 concealed by pereonite 7 and lateral margin posteriorly produced; pereopods 1-4 with three nodules on dactylus; endopod of pleopods 3-5 with a proximomedial lobe and folding; and pleotelson ovate, with lateral margins converging smoothly to a caudomedial point.

First record and molecular characterisation of two Gnathia species (Crustacea, Isopoda, Gnathiidae) from Philippine coral reefs, including a summary of all Central-Indo Pacific Gnathia species.

Due to their unusual life cycle that includes parasitic larval and free living adult stages, gnathiid isopods are typically overlooked in biodiversity surveys, even those that focus on parasites. While the Philippines sits within the region of highest marine biodiversity in the world, the coral triangle, no gnathiid species have been identified or described from that region. Here we present the first records of two gnathiid species collected from the Visayas, central Philippines: Gnathia malaysiensis Müller, 1993, previously described from Malaysia, and G. camuripenis Tanaka, 2004, previously described from southern Japan. This paper provides detailed morphological redescriptions, drawings and scanning electron microscope images as well as the first molecular characterisation of both species, Furthermore, a summary of the Central-Indo Pacific Gnathia species is provided.

Pseudodactylogyrus anguillae (Yin & Sproston, 1948) from the giant mottled eel Anguilla marmorata Quoy & Gaimard, 1824, in the Phongolo River, South Africa: an invader on the African continent.

The global invasive anguillid gill parasite Pseudodactylogyrus anguillae (Yin and Sproston, 1948) has only recently been documented from eels in South Africa. As there is no known eel trade in South Africa, the source of introduction of this parasite has been debated, and its status as an alien parasite was rendered uncertain. We report on the first infection of Pseudodactylogyrus anguillae from the giant mottled eel Anguilla marmorata from the Phongolo River (South Africa) using classic morphological and molecular methodologies and clarify the introduction status category of this parasite as alien and invasive.

Review of the global distribution and hosts of the economically important fish parasitic isopod genus Ceratothoa (Isopoda: Cymothoidae), including the description of Ceratothoa springbok n. sp. from South Africa.

Fish parasites from the isopod family Cymothoidae have, in recent years, received increased global attention due to both their ecological and economic importance. This is particularly true for the buccal inhabiting genus Ceratothoa Dana, 1852, whose members have been implicated in negatively impacting the health of both farmed and wild-caught fishes. As research on this group increases, so does our understanding of their host specificity and distribution. The aims of this paper were thus to review the current distribution and host records of Ceratothoa and describe a new species, Ceratothoa springbok n. sp. from South Africa. Including the new species described here, there are currently 25 accepted Ceratothoa spp. known from eight of the 12 marine biogeographical realms of the world. The majority of Cymothoidae species are known to occur in the tropical realms, whereas our analyses show that the greatest diversity of Ceratothoa spp. can be found in temperate realms. These results indicate the possibility that Ceratothoa is more diverse in temperate regions. This review also highlights the low diversity of Ceratothoa from the oceans around both North and South America. Current records indicate that species of Ceratothoa parasitise 108 fish species in 76 genera and 41 families. Eleven Ceratothoa spp. demonstrate host specificity up to host genus or family level. Amongst the hosts, members of the Sparidae are parasitised by 13 species of Ceratothoa, making it the host family with the highest diversity of parasites from this genus. The new species, C. springbok n. sp., also parasitises a sparid and was found in the buccal cavity of the carpenter seabream, Argyrozona argyrozona. This new species, the largest of all recorded Ceratothoa (up to 65 mm) and amongst the largest of all Cymothoidae, is characterised by its truncate and ventrally folded frontal margin, pereonite 1 with medial indentations, the wide anterolateral margins of pereonite 1 with an inwardly produced point, and a well-developed carina on the basis of pereopod 7. A key to the southern African Ceratothoa is provided.

Gnathia bermudensis (Crustacea, Isopoda, Gnathiidae), a new species from the mesophotic reefs of Bermuda, with a key to Gnathia from the Greater Caribbean biogeographic region.

Gnathia bermudensis sp. nov. is described from mesophotic coral ecosystems in Bermuda; it is distinguished by pronounced and pointed supraocular lobes, two superior frontolateral processes and a weak bifid mediofrontal process, pereonite 1 not fused dorsally with the cephalosome, and large eyes. This is the first record of a species of Gnathia from Bermuda. A synopsis and key to the other Gnathia species from the Greater Caribbean biogeographic region is provided.

A new genus and species of fish parasitic cymothoid (Crustacea, Isopoda) from the Indian Ocean coast of South Africa, with a key to the externally attaching genera of Cymothoidae.

Bambalocra intwala gen. et sp. nov. is described from Sodwana Bay, north-eastern South Africa. The monotypic genus is characterised by the broadly truncate anterior margin of the head with a ventral rostrum, coxae 2-5 being ventral in position not forming part of the body outline and not or barely visible in dorsal view, and the posterolateral margins of pereonites 6 and 7 are posteriorly produced and broadly rounded. The antennulae bases are widely separated, with both antennula and antenna slender. The species is known only from the type locality and the known hosts are species of Pomacanthidae (Angelfish). A revised key to the externally attaching genera of Cymothoidae is provided.

Hooked on you: shape of attachment structures in cymothoid isopods reflects parasitic strategy.

BACKGROUND: Parasite attachment structures are critical traits that influence effective host exploitation and survival. Morphology of attachment structures can reinforce host specificity and niche specialisation, or even enable host switching. Therefore, it is important to understand the determinants of variation in attachment structures. Cymothoid isopods are striking ectoparasites of fishes that include the infamous 'tongue-biters.' They are known to parasitise hosts in one of four qualitatively distinct anatomical regions. Here, we quantify variation in cymothoid attachment structures - hook-like appendages called dactyli - and test whether differences in dactylus shape are correlated with parasite mode (where they attach), allometry, or both, using multivariate ordinary least squares regression. We also assess the influence of shared ancestry on shape using a molecular phylogeny to weight our models using phylogenetic generalised least squares regression. RESULTS: We find clear differences in shape between externally-attaching and internally-attaching cymothoids but also between anterior and posterior dactyli across various species with the same attachment mode. Allometric effects are significant for anterior but not posterior dactyli. Mouth-attaching species show greater shape variability than gill- and mouth-attaching species. We find no evidence that there are clade-specific patterns of association between parasite mode and dactylus shape. CONCLUSIONS: Parasite mode appears to be the main driver of attachment morphology. This likely reflects several components of parasite ecology including feeding and functional demands of attachment in different microhabitats. Geometric morphometric approaches to the quantification of shape variation of simple structures is an effective tool that provides new insights into the evolvability of parasite attachment.

Review of the fish parasitic genus Elthusa Schioedte & Meinert, 1884 (Crustacea, Isopoda, Cymothoidae) from South Africa, including the description of three new species.

The branchial-attaching cymothoid genus, Elthusa Schioedte & Meinert, 1884 is a genus with a worldwide distribution of 36 species, including the three species described here. Elthusaraynaudii (Milne Edwards, 1840) is the only species that has been described from southern Africa. All South African material held at the National Museum of Natural History, Paris, France (MNHN) and the Iziko South African Museum, Cape Town (SAMC) identified as, or appearing to belong to, Elthusa was examined. Four species were identified, Elthusaraynaudii and three species that proved to be undescribed. Elthusaxena sp. n. can be distinguished by an evenly rounded pereonite 1 anterior margin, a roughly rectangular pleotelson, and narrowly rounded uropod apices that extend to more than half the length of the pleotelson. Elthusaacutinasa sp. n. is identified by the produced and narrowly rounded cephalon anterior margin, acute uropods that are shorter than half the length of the pleotelson, and pereonite 1 anterior margin with medial projection. Elthusarotunda sp. n. is characterised by the round body shape, broadly rounded uropod apices, and protrusions on the proximal and lateral margins of the merus and carpus of pereopod 7. A key to the South African Elthusa species is provided, together with a table summarising the hosts and localities of the 33 previously known species of Elthusa.

Understanding growth relationships of African cymothoid fish parasitic isopods using specimens from museum and field collections.

Cymothoid isopods are a diverse group of ectoparasites of fish species, and are particularly conspicuous as they are large and attach to the body surface, mouth, and gill chamber of fish hosts. These parasites transition from juvenile to male to female, and how their size changes with ontogeny and correlates with host size is not well understood. To better understand these relationships, data from field and museum collected samples of South Africa were combined to test for the associations between host and parasite length for three mouth and one gill chamber-infesting genera (Ceratothoa, Cinusa, Cymothoa, and Mothocya respectively). Generally, the number of parasites collected from 90 h of museum surveying was similar to that of seven, one-week long field collections. For two of the three mouth-infesting parasites, parasite and host size were significantly and positively correlated for males and females, but not juveniles. For gill chamber-infesting parasites, female and male parasite sizes were weakly and not significantly correlated with host size. These results provide the first morphometric data and growth relationship data for African cymothoid species and their fish hosts, and demonstrate the value and efficiency of using museum collections in ecological research.

Elthusa winstoni sp. n. (Isopoda, Cymothoidae), a new fish parasitic isopod from Hawaii.

The new cymothoid species, Elthusa winstonisp. n., a branchial parasite of fishes from the family Acanthuridae Bonaparte, 1835 in Hawaii, is described and figured. The female adults can be distinguished by the strongly vaulted body and compacted body shape; rostrum with a small median point; short antennae which are close together (only 6 articles in both antennula and antenna); short and wide uropods extending to half the length of the pleotelson; short dactyli on pereopod 7; and large recurved robust setae on the maxilla. This is the first record of an Elthusa Schioedte & Meinert, 1884 species from the Hawaiian Islands and only the fifth cymothoid described from this region.

Molecular assessment of three species of Anilocra (Isopoda, Cymothoidae) ectoparasites from Caribbean coral reef fishes, with the description of Anilocra brillae sp. n.

A morphological review and molecular characterization of Anilocra haemuli Bunkley Williams & Williams, 1981, were completed using specimens collected from Haemulon flavolineatum Desmarest, 1823 (French grunt) and Epinephelus guttatus Linnaeus, 1758 (red hind). Molecular and morphological data suggest that the isopods parasitizing H. flavolineatum and E. guttatus are different species. The specimens collected from E. guttatus are recognized as a new species, Anilocra brillaesp. n. Differences between Anilocra brillaesp. n. and A. haemuli include but are not limited to the pleonites 1-3 of A. brillaesp. n. being wider than 4-5 and 4-5 subequal, whereas the pleonites 1-2 of A. haemuli are wider than 3-5, and 3-5 are subequal. The seventh pereopod of A. brillaesp. n. is proportionally larger, has more robust setae, and the setae are distributed more extensively over the articles when compared to A. haemuli. Additionally, this study provides the first genetic characterization of three Anilocra spp. from the Caribbean, and is based on mitochondrial cytochrome c oxidase subunit gene (COI) for A. haemuli from H. flavolineatum, A. brillaesp. n. from E. guttatus, and A. chromis Bunkley Williams & Williams, 1981 from Chromis multilineata Guichenot, 1853.

Revision of the fish parasitic genus Pleopodias Richardson, 1910 (Isopoda, Cymothoidae), with the description of a new species and key to the genus.

The cymothoid genus, Pleopodias Richardson, 1910, is revised and a new species from South Africa is recorded. Pleopodias nielbruceisp. n. can be distinguished by large eyes covering majority of the cephalon (almost in contact), antennula bases wide apart, antenna extending to middle of pereonite 2, subtruncate pleotelson, pereopod 7 with numerous acute robust setae on the propodus as well as the carpus, and the uropod exopod longer than the endopod. The three known species, Pleopodias diaphus Avdeev, 1975; P. elongatus Richardson, 1910; and P. vigilans Richardson, 1911 are also redescribed. Pleopodias nielbruceisp. n. differs from these known species in both morphological characters as well as geographical distribution. A key to the Pleopodias species is provided.