Understanding the Influence of Host Radiation on Symbiont Speciation through Parasites of Species Flocks.

(Adaptive) radiations have attracted evolutionary biologists for a long time as ideal model systems to study patterns and processes of often rapid speciation. However, whereas a wealth of (sometimes already genome-scale) data is available for host radiations, very few studies target the patterns of diversification in their symbionts, even though they would be excellent models to study symbiont speciation. Our review summarizes what little is known about general patterns of symbiont diversification in often iconic adaptive host radiations and to what extent these patterns are dependent on the evolutionary trajectories of their hosts. We identify research gaps that need to be addressed in the future and discuss the potential of approaches not yet typically used in these study systems, such as epidemiological disease modeling and new omics technologies, for significantly advancing our understanding of these complex eco-evolutionary relationships.

All quiet on the western front? The evolutionary history of monogeneans (Dactylogyridae: Cichlidogyrus, Onchobdella) infecting a West and Central African tribe of cichlid fishes (Chromidotilapiini).

Owing to the largely unexplored diversity of metazoan parasites, their speciation mechanisms and the circumstances under which such speciation occurs - in allopatry or sympatry - remain vastly understudied. Cichlids and their monogenean flatworm parasites have previously served as a study system for macroevolutionary processes, e.g., for the role of East African host radiations on parasite communities. Here, we investigate the diversity and evolution of the poorly explored monogeneans infecting a West and Central African lineage of cichlid fishes: Chromidotilapiini, which is the most species-rich tribe of cichlids in this region. We screened gills of 149 host specimens (27 species) from natural history collections and measured systematically informative characters of the sclerotised attachment and reproductive organs of the parasites. Ten monogenean species (Dactylogyridae: Cichlidogyrus and Onchobdella) were found, eight of which are newly described and one redescribed herein. The phylogenetic positions of chromidotilapiines-infecting species of Cichlidogyrus were inferred through a parsimony analysis of the morphological characters. Furthermore, we employed machine learning algorithms to detect morphological features associated with the main lineages of Cichlidogyrus. Although the results of these experimental algorithms remain inconclusive, the parsimony analysis indicates that West and Central African lineages of Cichlidogyrus and Onchobdella are monophyletic, unlike the paraphyletic host lineages. Several instances of host sharing suggest occurrences of intra-host speciation (sympatry) and host switching (allopatry). Some morphological variation was recorded that may also indicate the presence of species complexes. We conclude that collection material can provide important insights on parasite evolution despite the lack of well-preserved DNA material.

Title: À l'Ouest, rien de nouveau ? L'histoire évolutive des monogènes (Dactylogyridae : Cichlidogyrus, Onchobdella) infectant une tribu de poissons cichlidés (Chromidotilapiini) d'Afrique occidentale et centrale. Abstract: En raison de la nature largement inexplorée de la diversité des parasites métazoaires, leurs mécanismes de spéciation et les circonstances dans lesquelles cette spéciation se produit­allopatrie ou sympatrie­restent très peu étudiés. Les cichlidés et leurs parasites Plathelminthes monogènes ont déjà servi de modèle pour l'étude des processus macro-évolutifs, par exemple pour le rôle des radiations d'hôtes de l'Afrique de l'Est sur les communautés de parasites. Ici, nous étudions la diversité et l'évolution des monogènes peu étudiées qui infestent une lignée de poissons cichlidés d'Afrique occidentale et centrale : les Chromidotilapiini, qui est la tribu de cichlidés la plus riche en espèces dans cette région. Nous avons examiné les branchies de 149 spécimens hôtes (27 espèces) provenant de musées d'histoire naturelle et mesuré systématiquement les caractères informatifs des pièces sclérifiées du hapteur et des organes copulateurs des parasites. Dix espèces de monogènes (Dactylogyridae : Cichlidogyrus et Onchobdella) ont été trouvées ; huit sont nouvelles pour la science et une est redécrite. Les positions phylogénétiques des espèces de Cichlidogyrus infectant les chromidotilapiines ont été déduites par une analyse de parcimonie des caractères morphologiques. En outre, nous avons utilisé des algorithmes d'apprentissage automatique pour détecter les caractéristiques morphologiques associées aux principales lignées de Cichlidogyrus. Bien que les résultats de ces algorithmes expérimentaux restent peu concluants, l'analyse de parcimonie indique que les lignées de Cichlidogyrus et d'Onchobdella de l'Afrique de l'Ouest et Central sont monophylétiques, contrairement aux lignées d'hôtes qui sont paraphylétiques. Plusieurs cas de partage d'hôtes suggèrent des occurrences de spéciation synxénique (sympatrie) et de changement d'hôte (allopatrie). Certaines variations morphologiques ont été enregistrées et peuvent également indiquer la présence de complexes d'espèces. Nous concluons donc que le matériel de collection peut fournir des informations importantes sur l'évolution des parasites malgré le manque d'ADN exploitable.

First Study on Gyrodactylus (Monogenea: Gyrodactylidae) in Morocco, with Description of a New Species from Luciobarbus pallaryi and Luciobarbus ksibi (Actinopterygii: Cyprinidae).

To date, 41 species of Gyrodactylus have been described from Africa. However, none of these have been reported in Morocco. After identifying and examining 738 cyprinid host specimens, 26 specimens belonging to Gyrodactylus were found to parasitize the gills of nine species of Luciobarbus, Carasobarbus, and Pterocapoeta. The current study provides new information about the presence of a new parasitic species in Morocco, the first to be characterized on a species level in the Maghreb region. It describes in detail 12 specimens of Gyrodactylus isolated from the gills of Luciobarbus pallaryi (Pellegrin, 1919) and Luciobarbus ksibi (Boulenger, 1905). Based on morphoanatomical observations, the characterization of the specimens collected indicates a species of Gyrodactylus that is new to science, described here as Gyrodactylus nyingiae n. sp. The new species is different from previously described gyrodactylids infecting African cyprinid hosts because it has a longer hamulus total length, a longer hamulus root, a downward projecting toe of the marginal hook, and a trapezium-shaped ventral bar membrane with a slightly striated median portion and small rounded anterolateral processes. This study increases the total number of Gyrodactylus spp. found in African cyprinids to four.

Monogeneans from Catfishes in Lake Tanganyika. II: New Infection Site, New Record, and Additional Details on the Morphology of the Male Copulatory Organ of Gyrodactylus transvaalensis Prudhoe and Hussey, 1977.

The ichthyofauna of Lake Tanganyika consists of 12 families of fish of which five belong to Siluriformes (catfishes). Studies on Siluriformes and their parasites in this lake are very fragmentary. The present study was carried out to help fill the knowledge gap on the monogeneans infesting the siluriform fishes of Lake Tanganyika in general and, more particularly, Clarias gariepinus. Samples of gills of Clarias gariepinus (Clariidae) were examined for ectoparasites. We identified the monogenean Gyrodactylus transvaalensis (Gyrodactylidae). This is the first time this parasite was found infecting gills. We are the first to observe a large spine in the male copulatory organ of this species and to provide measurements of its genital spines; this completes the description of the male copulatory organ, which is important in standard monogenean identification. This is the first monogenean species reported in C. gariepinus at Lake Tanganyika and the third known species on a representative of Siluriformes of this lake. It brings the total number of species of Gyrodactylus recorded in Lake Tanganyika to four. Knowing that other locations where this species has been reported are geographically remote from Lake Tanganyika, we propose a "failure to diverge" phenomenon for G. transvaalensis.

First record of monogenean fish parasites in the Upper Lufira River Basin (Democratic Republic of Congo): dactylogyrids and gyrodactylids infesting Oreochromis mweruensis, Coptodon rendalli and Serranochromis macrocephalus (Teleostei: Cichlidae).

BACKGROUND: Monogenean parasites have never been formally reported on fishes from the Lufira River Basin. In this context, we decided to record the monogenean parasite fauna of three cichlid species found in the Upper Lufira River Basin for the first time by inventorizing their diversity (species composition) and analysing their infection parameters (prevalence, mean intensity and abundance). METHODS: The African cichlid fishes Oreochromis mweruensis, Coptodon rendalli and Serranochromis macrocephalus were selected for the study, given their economic value and their abundance in the Upper Lufira River Basin. Monogeneans were isolated from the gills and stomach, mounted on glass slides with either Hoyer's medium or ammonium picrate-glycerin for identification under a stereomicroscope, based on morphological analysis of genital and haptoral hard parts. Indices of diversity and infections parameters were calculated. RESULTS: A total of 13 gill monogenean parasite species (Cichlidogyrus dossoui, C. halli, C. karibae, C. mbirizei, C. papernastrema, C. quaestio, C. sclerosus, C. tiberianus, C. tilapiae, C. zambezensis, Scutogyrus gravivaginus, S. cf. bailloni and Gyrodactylus nyanzae) and one stomach monogenean (Enterogyrus malmbergi) were identified. A species richness (S) of 10 for O. mweruensis, S = 6 for C. rendalli and S = 2 for S. macrocephalus was recorded. Five parasite species were reported to be common amongst O. mweruensis and C. rendalli. According to cichlid species, the most prevalent parasite species was C. halli (prevalence [P] = 80.9%) on O. mweruensis, C. dossoui (P = 92.9%) on C. rendalli and C. karibae and C. zambezensis (both P = 9.1%) on S. macrocephalus. The parasite species with the highest mean intensity (MI) were G. nyanzae (MI = 8.7) on O. mweruensis, C. papernastrema (MI = 17.1) on C. rendalli and C. karibae (MI = 15) on S. macrocephalus. The findings indicate new host ranges for five parasites species (C. quaestio, S. cf. bailloni, E. malmbergi on O. mweruensis, C. halli on C. rendalli and C. karibae on S. macrocephalus) as well as new geographical records for all of them as they are recorded for the first time in the Lufira River Basin. CONCLUSIONS: This study highlighted the richness of monogenean communities in the Upper Lufira River Basin and is a starting point for future helminthological studies, such as on the use of fish parasites as indicators of anthropogenic impacts.

Parasites of Moroccan desert Coptodon guineensis (Pisces, Cichlidae): transition and resilience in a simplified hypersaline ecosystem.

Sebkha Imlili (Atlantic Sahara) is a salt flat with over 160 permanent holes of hypersaline water generated in the Holocene and inhabited by euryhaline organisms that are considered to be relics of the past, including the cichlid fish Coptodon guineensis. We surveyed the fish parasites four times over one year, to i) identify the parasites, and ii) determine possible seasonality in infection patterns. Over 60% of the fish were infected by one to three helminths: an acanthocephalan in the intestine and two digenean metacercariae in the kidney, spleen, liver, muscle, and mesenteries. The acanthocephalan Acanthogyrus (Acanthosentis) cf. tilapiae was identified morphologically and molecularly; only one digenean (the heterophyid Pygidiopsis genata) could be identified molecularly. Both identified parasites were present throughout the sampling periods; the unidentified metacercariae were present only in summer and fall. Mean intensities, but not prevalence of infection by the acanthocephalan, reflected a biannual pattern of transmission. Infection accrued with fish size, possibly due to cannibalism. Because the water holes include only a few invertebrates, the intermediate hosts of these parasites can be inferred to be the gastropod Ecrobia ventrosa for the digeneans and either the copepod Cletocamtpus retrogressus or the ostracod Cyprideis torosa for the acanthocephalan. This ecosystem appears stable and provides a window into the past, as the acanthocephalan likely switched from freshwater tilapia to C. guineensis when the Sebkha formed. However, this is a vulnerable environment where the survival of these parasites depends on interactions maintained among only very few hosts.

Title: Parasites de Coptodon guineensis (Pisces, Cichlidae) du désert marocain : transition et résilience dans un écosystème hypersalin simplifié. Abstract: La Sebkha d'Imlili est une sebkha (étendue désertique sableuse et salée) dans le Sahara Atlantique caractérisée par la présence de plus de 160 poches permanentes d'eau hypersaline qui sont apparues à l'Holocène et qui sont habitées par des organismes considérés comme des reliques du passé, dont un poisson cichlidé, Coptodon guineensis. Nous avons fait l'inventaire des parasites de ce poisson au cours des quatre saisons d'une année pour 1) identifier les parasites et 2) déterminer une éventuelle transmission saisonnière. Plus de 60 % des poissons étaient infestés par un à trois helminthes : un Acanthocéphale dans l'intestin et des métacercaires de deux espèces de Digène dans le rein, la rate, les muscles et le mésentère. L'Acanthocéphale Acanthogyrus (Acanthosentis) cf. tilapiae a été identifié morphologiquement et génétiquement mais seul un des deux Digènes (l'hétérophyidé Pygidiopsis genata) a pu être identifié par séquençage. Ces deux parasites étaient présents à chaque période d'étude, mais la métacercaire non identifiée était présente seulement en été et en automne. L'intensité moyenne de l'infestation par l'Acanthocéphale, mais pas sa prévalence, reflète une transmission biannuelle. L'infestation augmente avec la taille du poisson, peut-être à cause du cannibalisme. L'identité des hôtes intermédiaires de ces parasites peut être avancée parce que cet écosystème est simplifié et inclut seulement quelques invertébrés : pour les Digènes, le Gastéropode Ecrobia ventrosa, et pour l'Acanthocéphale, le Copépode Cletocamtpus retrogressus ou l'Ostracode Cyprideis torosa. Cet écosystème apparait stable et offre une vue sur le passé étant donné que l'Acanthocéphale a sans doute été transféré d'un tilapia d'eau douce quand la sebkha s'est formée. Cependant, c'est un environnement vulnérable où la survie de ces parasites dépend d'interactions entre très peu d'espèces hôtes.

Description of a new species from Clarias maclareni and phylogenetical analysis of Quadriacanthus (Monogenea, Dactylogyridae) species transfers between clariid and non-clariid fish hosts in Cameroon.

Recently in Cameroon, two species belonging to Quadriacanthus: Q. anaspidoglanii Akoumba, Tombi & Bilong Bilong, 2017 and Q. euzeti Nack, Pariselle & Bilong Bilong, 2016 have been recorded on gill filaments of Notoglanidium macrostoma (Siluriformes, Claroteidae) in the Memou'ou River (Nyong Basin) and Papyrocranus afer (Osteoglossiformes, Notopteridae) in Lake Ossa, respectively. These records have been considered the result of lateral transfers from Clariidae to a Claroteidae host for the first case (parasitism of N. macrostoma by Q. anaspidoglanii) and from Clariidae or Bagridae to a Notopteridae host for the second (parasitism of P. afer by Q. euzeti). In this paper, the investigation of interspecific relationships among Quadriacanthus spp. parasitizing Clariidae, Bagridae, Claroteidae and Notopteridae in Cameroon resulted in the record of Q. anaspidoglanii from N. macrostoma, Q. euzeti from P. afer, a new record of Q. levequei Birgi, 1988 from Clarias jaensis in the Nyong River, and the description of Q. barombiensis n. sp. from Clarias maclareni in Lake Barombi Mbo. The newly identified species is characterized by having an accessory piece ending in one small hook and the median expansion of its dorsal bar with two filaments. Phylogenetic analysis based on 28S rDNA sequences confirms that the Quadriacanthus spp. parasitizing gill filaments of non-clariid hosts in Cameroon originate from lateral transfers from clariid fishes, and that Clariidae are ancestral hosts of these monogenean species.

Title: Description d'une nouvelle espèce parasite de Clarias maclareni et analyse phylogénétique des transferts d'espèces de Quadriacanthus (Monogenea, Dactylogyridae) entre poissons hôtes clariidés et non clariidés au Cameroun. Abstract: Récemment au Cameroun deux espèces appartenant à Quadriacanthus : Q. anaspidoglanii Akoumba, Tombi & Bilong Bilong, 2017 et Q. euzeti Nack, Pariselle & Bilong Bilong, 2016 ont été signalées, respectivement sur les filaments branchiaux de Notoglanidium macrostoma (Siluriformes, Claroteidae), dans la rivière Memou'ou (bassin du Nyong) et Papyrocranus afer (Osteoglossiformes, Notopteridae) dans le lac Ossa. Ces signalements ont été considérés comme le résultat de transferts latéraux de Clariidae vers un hôte Claroteidae pour le premier cas (parasitisme de N. macrostoma par Q. anaspidoglanii) et d'un Clariidae ou Bagridae vers un hôte Notopteridae pour le second (parasitisme de P. afer par Q. euzeti). Dans cet article, l'étude des relations interspécifiques entre Quadriacanthus spp. parasitant des Clariidae, Bagridae, Claroteidae et Notopteridae au Cameroun a abouti au signalement de Q. anaspidoglanii chez N. macrostoma, Q. euzeti chez P. afer, un nouveau signalement de Q. levequei Birgi, 1988 chez Clarias jaensis dans le fleuve Nyong, et à la description de Q. barombiensis n. sp. chez Clarias maclareni dans le lac Barombi Mbo. L'espèce nouvellement identifiée se caractérise par la présence d'une pièce accessoire se terminant par un petit crochet et l'expansion médiane de sa barre dorsale avec deux filaments. L'analyse phylogénétique basée sur les séquences d'ADNr 28S confirme que les Quadriacanthus spp. des filaments branchiaux parasitant des hôtes non-clariidés au Cameroun proviennent de transferts latéraux de poissons clariidés, et que les Clariidae sont bien les hôtes ancestraux de ces espèces de monogènes.

Explosive networking: The role of adaptive host radiations and ecological opportunity in a species-rich host-parasite assembly.

Many species-rich ecological communities emerge from adaptive radiation events. Yet the effects of adaptive radiation on community assembly remain poorly understood. Here, we explore the well-documented radiations of African cichlid fishes and their interactions with the flatworm gill parasites Cichlidogyrus spp., including 10,529 reported infections and 477 different host-parasite combinations collected through a survey of peer-reviewed literature. We assess how evolutionary, ecological, and morphological parameters determine host-parasite meta-communities affected by adaptive radiation events through network metrics, host repertoire measures, and network link prediction. The hosts' evolutionary history mostly determined host repertoires of the parasites. Ecological and evolutionary parameters predicted host-parasite interactions. Generally, ecological opportunity and fitting have shaped cichlid-Cichlidogyrus meta-communities suggesting an invasive potential for hosts used in aquaculture. Meta-communities affected by adaptive radiations are increasingly specialised with higher environmental stability. These trends should be verified across other systems to infer generalities in the evolution of species-rich host-parasite networks.

Somewhere I belong: phylogeny and morphological evolution in a species-rich lineage of ectoparasitic flatworms infecting cichlid fishes.

A substantial portion of biodiversity has evolved through adaptive radiation. However, the effects of explosive speciation on species interactions remain poorly understood. Metazoan parasites infecting radiating host lineages could improve our knowledge because of their intimate host relationships. Yet limited molecular, phenotypic and ecological data discourage multivariate analyses of evolutionary patterns and encourage the use of discrete characters. Here, we assemble new molecular, morphological and host range data widely inferred from a species-rich lineage of parasites (Cichlidogyrus, Platyhelminthes: Monogenea) infecting cichlid fishes to address data scarcity. We infer a multimarker (28S/18S rDNA, ITS1, COI mtDNA) phylogeny of 58 of 137 species and characterize major lineages through synapomorphies inferred from mapping morphological characters. We predict the phylogenetic position of species without DNA data through shared character states, a morphological phylogenetic analysis, and a classification analysis with support vector machines. Based on these predictions and a cluster analysis, we assess the systematic informativeness of continuous characters, search for continuous equivalents for discrete characters, and suggest new characters for morphological traits not analysed to date. We also model the attachment/reproductive organ and host range evolution using the data for 136 of 137 described species and multivariate phylogenetic comparative methods (PCMs). We show that discrete characters not only can mask phylogenetic signals, but also are key for characterizing species groups. Regarding the attachment organ morphology, a divergent evolutionary regime for at least one lineage was detected and a limited morphological variation indicates host and environmental parameters affecting its evolution. However, moderate success in predicting phylogenetic positions, and a low systematic informativeness and high multicollinearity of morphological characters call for a revaluation of characters included in species characterizations.

Dactylogyridae 2022: a meta-analysis of phylogenetic studies and generic diagnoses of parasitic flatworms using published genetic and morphological data.

Dactylogyridae is one of the most studied families of parasitic flatworms with more than 1000 species and 166 genera described to date including ecto- and endoparasites. Dactylogyrid monogeneans were suggested as model organisms for host-parasite macroevolutionary and biogeographical studies due to the scientific and economic importance of some of their host lineages. Consequently, an array of phylogenetic research into different dactylogyrid lineages has been produced over the past years but the last family-wide study was published 16 years ago. Here, we provide a meta-analysis of the phylogenetic relationships of Dactylogyridae including representatives of all genera with available molecular data (n = 67). First, we investigate the systematic informativeness of morphological characters widely used to diagnose dactylogyrid genera through a parsimony analysis of the characters, character mapping, and phylogenetic comparative methods. Second, we provide an overview of the current state of the systematics of the family and its subfamilies, and summarise potentially poly- and paraphyletic genera. Third, we elaborate on the implications of taxonomic, citation, and confirmation bias in past studies. Fourth, we discuss host range, biogeographical, and freshwater-marine patterns. We found two well-supported macroclades which we assigned to the subfamilies Dactylogyrinae and Ancyrocephalinae. These subfamilies further include 16 well-supported clades with only a few synapomorphies that could be deduced from generic diagnoses in the literature. Furthermore, few morphological characters considered systematically informative at the genus level display a strong phylogenetic signal. However, the parsimony analysis suggests that these characters provide little information on the relationships between genera. We conclude that a strong taxonomic bias and low coverage of DNA sequences and regions limit knowledge on morphological and biogeographical evolutionary patterns that can be inferred from these results. We propose addressing potential citation and confirmation biases through a 'level playing field' multiple sequence alignment as provided by this study.

Monogeneans from Catfishes in Lake Tanganyika. I: Two new species of Bagrobdella Paperna, 1969 (Dactylogyridae) from Auchenoglanis occidentalis (Valenciennes, 1840) (Siluriformes: Claroteidae)

In the framework of the study of Siluriform fish monogeneans of Lake Tanganyika, we described two new species of Bagrobdella from Auchenoglanis occidentalis, Bagrobdella vanhovei sp. nov. is characterized by the morphology of its MCO which is unique (terminal opening) and Bagrobdella vansteenbergei sp. nov. characterized by the size of its hooks, which are almost all of the same size, and its male copulating organ with a unique shape: sub-terminal opening and no membrane surrounding.

Two new Quadriacanthus Species (Monogenea: Dactylogyridae) Including a New Geographical Record of Quadriacanthus mandibulatus Francová & Rehulková, 2017, Gill Parasites from Heterobranchus bidorsalis (Siluriformes) in Côte d'Ivoire.

PURPOSE: To study the monogeneans gill parasites of Heterobranchus bidorsalis (Siluriformes, Clariidae) fish of economic interest in the Bagoue River. METHODS: Fifty-five specimens of H. bidorsalis were caught with gillnets in the Bagoué River from August 2018 to January 2019. The monogeneans were individually isolated from the gill and transferred directly onto a slide in a drop of glycerin ammonium picrate mixture (GAP). RESULTS: The new species differ from the previously described Quadriacanthus spp. mainly by the morphology of their sclerotised vagina: Quadriacanthus tanoyaoi sp. nov having a V-shaped, widely open vagina with a central protuberance, and Quadriacanthus bidorsalisi sp. nov having a pear-shaped vagina, composed of a tubular part with a ring near the aperture and a swollen portion. Q. tanoyaoi sp. nov and Q. bidorsalisi sp. nov are different in the shape of the dorsal and ventral anchors (more sturdy for Q. tanoyaoi), of the dorsal and ventral cuneus (triangular vs Y-shaped, respectively), and that of the vagina (V-shaped, widely open with a central protuberance vs pear-shaped, respectively). CONCLUSION: To date, only Quadriacanthus mandibulatus Francová & Rehulková, 2017 were recognised parasitizing from H. bidorsalis from the Nile River Basin (Sudan) and Lake Turkana (Kenya). The present study with the description of 2 new species expands the number to 3 species of monogeneans for this fish.

Integrating morphological and molecular approaches for characterizing four species of Dactylogyrus (Monogenea: Dactylogyridae) from Moroccan cyprinids, with comments on their host specificity and phylogenetic relationships.

Cyprinid fishes are known to harbour highly host-specific gill-associated parasites of Dactylogyrus. High similarity in the morphology of sclerotized structures among Dactylogyrus species, especially those parasitizing congeneric cyprinoids, makes their identification difficult. In this paper, four previously known species of Dactylogyrus are characterized and illustrated under a reliable taxonomic framework integrating morphological and molecular evidence, and their phylogenetic relationships are investigated using molecular data. The species are as follows: D. borjensis from Luciobarbus zayanensis; D. draaensis from Luciobarbus lepineyi; D. ksibii from Luciobarbus ksibi and Luciobarbus rabatensis; and D. marocanus from Carasobarbus fritschii, L. ksibi, L. zayanensis and Pterocapoeta maroccana. Our results revealed intraspecific genetic variability among specimens of D. ksibii collected from two different hosts and geographically distant basins. Phylogenetic reconstruction showed that Dactylogyrus spp. parasitizing Moroccan cyprinids are representatives of three main lineages corresponding to morphological differences and host specificity. Our records of D. marocanus on L. zayanensis and P. maroccana increase the range of available host species i.e.,eight species of four cyprinid genera representing two phylogenetic lineages (i.e., Barbinae and Torinae).

Six new species of Cichlidogyrus Paperna, 1960 (Platyhelminthes: Monogenea) from the gills of cichlids (Teleostei: Cichliformes) from the Lomami River Basin (DRC: Middle Congo).

BACKGROUND: Monogenea van Beneden, 1858 is a group of parasitic flatworms, commonly found infecting bony fish. Several genera, such as Cichlidogyrus Paperna, 1960, are reported to include potential pathogenic species that can negatively impact aquaculture fish stocks. They can switch from introduced to native fish and vice versa. In Africa (and all over the world), fish species belonging to Cichlidae are often kept in aquaculture and represent a major source of food. Thus, research on the biodiversity and occurrence of monogenean species on these fish is of importance for aquaculture and conservation. The present study is a survey of the diversity of species of Cichlidogyrus in the south of the Democratic Republic of the Congo (DRC) on three cichlid species: Orthochromis sp. 'Lomami', Serranochromis cf. macrocephalus, and Tilapia sparrmanii Smith, 1840. METHODS: Specimens of Cichlidogyrus were isolated from the gills and mounted on glass slides with Hoyer's medium. The genital and haptoral hard parts were measured and drawn using interference contrast. RESULTS: In total, six species of Cichlidogyrus were found, all new to science: C. bulbophallus n. sp. and C. pseudozambezensis n. sp. on S. cf. macrocephalus, C. flagellum n. sp. and C. lobus n. sp. on T. sparrmanii, C. ranula n. sp. on S. cf. macrocephalus and Orthochromis sp. 'Lomami', and C. maeander n. sp. found on Orthochromis sp. 'Lomami' and T. sparrmanii. The first four species are considered to be strict specialists, C. ranula n. sp. an intermediate generalist and C. maeander n. sp. a generalist. These parasite species show morphological similarities to species found in the Lower Guinea and Zambezi ichthyofaunal provinces, which might be explained by past river capture events between river systems of the Congo Province and both these regions. CONCLUSIONS: Serranochromis cf. macrocephalus and Orthochromis sp. 'Lomami' can harbour respectively three and two species of Cichlidogyrus, all described in this study. Tilapia sparrmanii can harbour seven species, of which three are described in the present study. These results highlight the species diversity of this parasite genus in the Congo Basin.

Temporally consistent species differences in parasite infection but no evidence for rapid parasite-mediated speciation in Lake Victoria cichlid fish.

Parasites may have strong eco-evolutionary interactions with their hosts. Consequently, they may contribute to host diversification. The radiation of cichlid fish in Lake Victoria provides a good model to study the role of parasites in the early stages of speciation. We investigated patterns of macroparasite infection in a community of 17 sympatric cichlids from a recent radiation and 2 older species from 2 nonradiating lineages, to explore the opportunity for parasite-mediated speciation. Host species had different parasite infection profiles, which were only partially explained by ecological factors (diet, water depth). This may indicate that differences in infection are not simply the result of differences in exposure, but that hosts evolved species-specific resistance, consistent with parasite-mediated divergent selection. Infection was similar between sampling years, indicating that the direction of parasite-mediated selection is stable through time. We morphologically identified 6 Cichlidogyrus species, a gill parasite that is considered a good candidate for driving parasite-mediated speciation, because it is host species-specific and has radiated elsewhere in Africa. Species composition of Cichlidogyrus infection was similar among the most closely related host species (members of the Lake Victoria radiation), but two more distantly related species (belonging to nonradiating sister lineages) showed distinct infection profiles. This is inconsistent with a role for Cichlidogyrus in the early stages of divergence. To conclude, we find significant interspecific variation in parasite infection profiles, which is temporally consistent. We found no evidence that Cichlidogyrus-mediated selection contributes to the early stages of speciation. Instead, our findings indicate that species differences in infection accumulate after speciation.

Three new species of Synodontella (Monogenea, Ancyrocephalidae), gill parasites of Synodontis spp. (Siluriformes, Mochokidae) from Côte d'Ivoire.

Four species of Synodontella, including three new, are reported from three species of Synodontis (S. ocellifer, S. nigrita, and S. velifer) from north-western Côte d'Ivoire. Synodontella melanoptera Dossou & Euzet, 1993 was found on the gills of S. nigrita and S. velifer and was already known from the gills of S. melanopterus in Benin and the gills of S. obesus and S. rebeli in Cameroon. The new species are Synodontella speroadotevii n. sp. from S. nigrita (type-host), S. velifer and S. ocellifer, and Synodontella bagoueensis n. sp. and Synodontella akengboi n. sp., both from S. velifer (type-host for both), S. nigrita and S. ocellifer. The new species differ from the other species of Synodontella mainly in the morphology of their male copulatory organs (MCO): Synodontella speroadotevii has a two-part penis (one being a hollow tube and the other a flattened tube); Synodontella bagoueensis has a wide G-shaped penis with a sub-terminal opening; and Synodontella akengboi has a simple narrow J-shaped penis. Synodontella speroadotevii differs from Synodontella bagoueensis and Synodontella akengboi in the shape of the dorsal transverse bar, which shows no protuberance, and also in the morphology of the MCO. Synodontella bagoueensis differs from the other two species in that it has a dorsal transverse bar that is V-shaped and a G-shaped MCO. Synodontella akengboi differs from the two other species in having a J-shaped MCO and in the size of its ventral and dorsal anchors which, contrary to the other two species, are almost similar.

TITLE: Trois nouvelles espèces de Synodontella (Monogenea, Ancyrocephalidae), parasites branchiaux de Synodontis spp. (Siluriformes, Mochokidae) en Côte d'Ivoire. ABSTRACT: Quatre espèces de Synodontella, dont trois nouvelles, sont signalées chez trois espèces de Synodontis (S. ocellifer, S. nigrita et S. velifer) du nord-ouest de la Côte d'Ivoire. Synodontella melanoptera Dossou & Euzet, 1993 a été trouvé sur les branchies de S. nigrita et S. velifer et était déjà connu des branchies de S. melanopterus au Bénin et des branchies de S. obesus et S. rebeli au Cameroun. Les nouvelles espèces sont Synodontella speroadotevii n. sp. de S. nigrita (hôte type), S. velifer et S. ocellifer et Synodontella bagoueensis n. sp. et Synodontella akengboi n. sp., tous deux de S. velifer (hôte type pour les deux), S. nigrita et S. ocellifer. Les nouvelles espèces se distinguent des autres espèces de Synodontella principalement par la morphologie de leurs organes copulateurs mâles (OCM) : Synodontella speroadotevii a un pénis en deux parties (l'une étant un tube creux et l'autre un tube aplati) ; Synodontella bagoueensis a un large pénis en forme de G avec une ouverture subterminale ; et Sy. akengboi a un pénis simple et étroit en forme de J. Synodontella speroadotevii diffère de Sy. bagoueensis et Sy. akengboi par la forme de la barre transversale dorsale, qui ne montre aucune protubérance, ainsi que dans la morphologie de l'OCM. Synodontella bagoueensis se distingue des deux autres espèces par sa barre transversale dorsale en forme de V et un OCM en forme de G. Synodontella akengboi diffère des deux autres espèces par son OCM en forme de J et par la taille de ses crochets ventraux et dorsaux qui, contrairement aux deux autres espèces, sont presque similaires.

New species of Synodontella (Monogenea, Ancyrocephalidae) gill parasites of two Synodontis spp. (Pisces, Mochokidae) from the Boumba River (Congo Basin, East Cameroon).

Three new species of Synodontella Dossou & Euzet, 1993 are described from two species of Synodontis (Mochokidae) collected from the middle course of the Boumba River (East Cameroon): Synodontella angustupenis n. sp. from Synodontis nummifer, Synodontella longipenis n. sp. and Synodontella simplex n. sp. from Synodontis decorus. These new species are different from the other Synodontella species already described due to their horseshoe-shaped dorsal transverse bars. Synodontella angustupenis differs from S. longipenis and S. simplex by the morphology of its penis, a thin tube, and its accessory piece, bifid at its extremity. Synodontella longipenis differs from the other two species by the morphology and the size of its male copulatory organ, which is very long. Synodontella simplex differs from S. angustupenis and S. longipenis by the shape of its penis, which is simple, and of its accessory piece, with a developed heel. The difference between the dorsal transverse bars of Synodontella species from the Sanaga River in Cameroon (and other localities in Africa), slightly curved, and those from the Boumba River, horseshoe-shaped, makes it possible to separate Synodontella species into two different subgroups. This difference can be explained by a long isolation period of the hosts, living in different river basins, followed by the divergence of the parasite populations (vicariant speciation).

TITLE: Trois nouvelles espèces de Synodontella (Monogenea, Ancyrocephalidae), parasites des branchies de deux espèces de Synodontis (Pisces, Mochokidae) de la rivière Boumba (bassin du Congo, Est Cameroun). ABSTRACT: Trois nouvelles espèces de Synodontella Dossou & Euzet, 1993 sont décrites chez deux espèces de Synodontis (Mochokidae) collectées dans le cours moyen de la rivière Boumba (Est Cameroun) : Synodontella angustupenis n. sp. de Synodontis nummifer, Synodontella longipenis n. sp. et Synodontella simplex n. sp. de Synodontis decorus. Ces nouvelles espèces sont différentes des autres espèces de Synodontella déjà décrites par leurs barres transversales dorsales en forme de fer à cheval. Synodontella angustupenis diffère de S. longipenis et de S. simplex par la morphologie de son pénis, un tube fin et de sa pièce accessoire, bifide à son extrémité. Synodontella longipenis diffère des deux autres espèces par la morphologie et la taille de son organe copulateur mâle, qui est très long. Synodontella simplex se distingue de S. angustupenis et S. longipenis par la forme de son pénis, qui est simple, et de sa pièce accessoire, avec un talon développé. La différence entre les barres transversales dorsales des espèces de Synodontella du fleuve Sanaga au Cameroun (et d'autres localités africaines), légèrement incurvées, et celles de la rivière Boumba, en forme de fer à cheval, permet de séparer les espèces de Synodontella en deux sous-groupes différents. Cette différence peut être expliquée par une longue période d'isolement des hôtes, vivant dans différents bassins hydrographiques, suivie de la divergence des populations de parasites (spéciation vicariante).

Monogenean fauna of alien tilapias (Cichlidae) in south China.

Tilapias are important aquaculture fishes that have been introduced widely all over the world, often carrying their monogenean parasites with them. An extensive investigation on monogeneans of invasive tilapias was conducted in 19 natural water sources in south China between July 2015 and December 2017. We found nine known species of monogeneans, i.e., Enterogyrus coronatus, E. malmbergi, Cichlidogyrus cirratus, C. halli, C. sclerosus, C. thurstonae, C. tilapiae, Scutogyrus longicornis, Gyrodactylus cichlidarum, and one unknown Gyrodactylus species. In addition to reporting ten new hosts and four new geographical records, we observed new morphological characteristics of these species. Observation on living specimens of Enterogyrus spp. demonstrated that these two species have characteristic opisthaptoral retraction capacities, while the opisthaptor glands were not observed in our specimens of E. coronatus and E. malmbergi. The morphological differences of the accessory piece of the male copulatory complex between C. cirratus and C. mbirizei (character for species differentiation) could result from the observation at different perspectives, which indicates that C. mbirizei is likely a synonym of C. cirratus. A more detailed structure of the sclerotized parts of Cichlidogyrus spp. and S. longicornis were revealed by scanning electron microscopy. As was the case for the monogeneans found on alien tilapias from other geographic regions, the present study confirmed the high potential of these monogeneans to establish populations in new habitats.

Six new dactylogyrid species (Platyhelminthes, Monogenea) from the gills of cichlids (Teleostei, Cichliformes) from the Lower Congo Basin.

The Lower Congo Basin is characterized by a mangrove-lined estuary at its mouth and, further upstream, by many hydrogeographical barriers such as rapids and narrow gorges. Five localities in the mangroves and four from (upstream) left bank tributaries or pools were sampled. On the gills of Coptodon tholloni, Coptodon rendalli, Hemichromis elongatus, Hemichromis stellifer and Tylochromis praecox, 17 species of parasites (Dactylogyridae & Gyrodactylidae, Monogenea) were found, eight of which are new to science. Six of these are herein described: Cichlidogyrus bixlerzavalai n. sp. and Cichlidogyrus omari n. sp. from T. praecox, Cichlidogyrus calycinus n. sp. and Cichlidogyrus polyenso n. sp. from H. elongatus, Cichlidogyrus kmentovae n. sp. from H. stellifer and Onchobdella ximenae n. sp. from both species of Hemichromis. On Cichlidogyrus reversati a ridge on the accessory piece was discovered that connects to the basal bulb of the penis. We report a putative spillback effect of the native parasites Cichlidogyrus berradae, Cichlidogyrus cubitus and Cichlidogyrus flexicolpos from C. tholloni to the introduced C. rendalli. From our results, we note that the parasite fauna of Lower Congo has a higher affinity with the fauna of West African and nearby freshwater ecoregions than it has with fauna of other regions of the Congo Basin and Central Africa.

A euryhaline fish, lost in the desert: The unexpected metapopulation structure of Coptodon guineensis (Günther, 1862) in the Sebkha of Imlili.

Euryhaline Cichlid fish of the species Coptodon guineensis are present in different water holes situated in a dried depression in the desert in the extreme South of Morocco, the Sebkha of Imlili. A genetic survey of this population, using complete sequences of the ND2 gene (mtDNA) and sixteen microsatellite loci, revealed that the fish in the sebkha did not form a single population, but rather a metapopulation. This metapopulational structure may be regarded as good news from the point of view of the conservation of fish in the sebkha. Although small individual populations may have short, finite life spans, the metapopulation as a whole is more stable, because immigrants from one population are likely to re-colonize the habitat, left open by the extinction of another.