Antoine Pariselle

Systematic revision of dactylogyridean parasites (Monogenea) from cichlid fishes in Africa, the Levant and Madagascar.

Pariselle A. & Euzet L. 2009. — Systematic revision of dactylogyridean parasites (Monogenea) from cichlid fishes in Africa, the Levant and Madagascar. Zoosystema 31 (4): 849-898. ABSTRACT Systematic revision is made of the six dactylogyridean genera (Monogenea) described on African, Levantine and Malagasy cichlid fishes: Urogyrus Bilong Bilong, Birgi & Euzet, 1994 (including one species); Enterogyrus Paperna, 1963 (including eight species); Insulacleidus Rakotofiringa & Euzet, 1983 (including three species); Onchobdella Paperna, 1968 (including eight species); Scutogyrus Pariselle & Euzet, 1995 (including six species) and Cichlidogyrus Paperna, 1960 (including 71 species). Validities of species are discussed. Diagnoses and illustrated determination keys are given for all taxa.

Monogeneans of West African Cichlid Fish: Evolution and Cophylogenetic Interactions

The goals of this paper were to investigate phylogenetic and evolutionary patterns of cichlid fish from West Africa and their Cichlidogyrus and Scutogyrus monogenean parasites, to uncover the presence of host-parasite cospeciation and to assess the level of morphological adaptation in parasites. This required the following steps, each one representing specific objectives of this paper: (1) to build phylogenetic trees for Cichlidogyrus and Scutogyrus species based on ribosomal DNA sequences, (2) to investigate phylogenetic relationships within West African cichlid fish based on the analysis of mitochondrial cytochrome b DNA sequences, (3) to investigate host-parasite cophylogenetic history to gain clues on parasite speciation process, and (4) to investigate the link between the morphology of the attachment apparatus and parasite phylogeny. Phylogenetic analyses supported the monophyletic origin of the Cichlidogyrus/Scutogyrus group, and suggested that Cichlidogyrus is polyphyletic and that Scutogyrus is monophyletic. The phylogeny of Cichlidae supported the separation of mouthbrooders and substrate-brooders and is consistent with the hypothesis that the mouthbrooding behavior of Oreochromis and Sarotherodon evolved from substrate-brooding behavior. The mapping of morphological characters of the haptor onto the parasite phylogenetic tree suggests that the attachment organ has evolved from a very simple form to a more complex one. The cophylogenetic analyses indicated a significant fit between trees using distance-based tests, but no significant cospeciation signal using tree-based tests, suggesting the presence of parasite duplications and host switches on related host species. This shed some light on the diversification process of Cichlidogyrus species parasitizing West African cichlids.

Ancyrocephalidae (Monogenea) of Lake Tanganyika: II: description of the first Cichlidogyrus spp. parasites from Tropheini fish hosts (Teleostei, Cichlidae).

Although Lake Tanganyika hosts the most diverse endemic cichlid fish assemblage, its monogenean parasite fauna has hardly been documented. The cichlid tribe Tropheini has generated great interest because of its systematic position within the Haplochromini s.l. and its diversity in trophic morphology, reproductive behaviour and population structure. It has the potential to host a diverse Monogenea fauna. Here, we describe the first Cichlidogyrus spp.: Cichlidogyrus steenbergei sp. n., Cichlidogyrus irenae sp. n. and Cichlidogyrus gistelincki sp. n. The three host species, Limnotilapia dardennii, Ctenochromis horei and Gnathochromis pfefferi, are all infected by a single unique Cichlidogyrus sp. The genital and haptoral structure of the new species suggests a close relationship, which might mirror the close affinities between the hosts within the Tropheini. Based on haptoral configuration, the new species belong to a morphological group within the genus containing parasites both of West African cichlids and of Haplochromini, and hence, do not represent a new organisation of the attachment organ (as has recently been described of congeners infecting the ectodine cichlid Ophthalmotilapia).

Ancyrocephalidae (Monogenea) of Lake Tanganyika. III : Cichlidogyrus infecting the world's biggest cichlid and the non-endemic tribes Haplochromini, Oreochromini and Tylochromini (Teleostei, Cichlidae)

Lake Tanganyika is the deepest and oldest African Great Lake and of economic importance. While the diversity of its endemic cichlid radiations yielded scientific interest, a number of cichlid tribes have few representatives in the lake. Some of those, namely Oreochromini (ex-Tilapiini), Haplochromini and Tylochromini, reach higher species numbers in riverine systems. Conversely, the phylogenetic position of the monospecific and endemic Boulengerochromini is unclear. The oreochromines Oreochromis tanganicae and Oreochromis niloticus, the haplochromine Astatotilapia burtoni, the tylochromine Tylochromis polylepis and the boulengerochromine Boulengerochromis microlepis, the largest cichlid species worldwide, were surveyed for ancyrocephalid monogenean gill parasites. Five new species are proposed. Cichlidogyrus gillardinae sp. n. is described from A. burtoni, Cichlidogyrus mbirizei sp. n. from O. tanganicae and Cichlidogyrus nshomboi sp. n. from B. microlepis. T. polylepis harbours Cichlidogyrus mulimbwai sp. n., Cichlidogyrus muzumanii sp. n. and a third, presently undescribed species. Four species known from outside the Tanganyika Basin were retrieved on the oreochromines. The host species are scientific models or important in the sectors of fisheries or ornamental fish trade. Moreover, their phylogenetic positions render them well-suited to help elucidate the historic relationships between riverine and lacustrine African cichlids. In this framework, their Cichlidogyrus fauna is compared to congeners known from African rivers and to the few Tanganyika representatives described. While the parasites of Oreochromis, A. burtoni and T. polylepis are reminiscent of those infecting related hosts throughout Africa, B. microlepis hosts a Cichlidogyrus morphotype typical of Lake Tanganyika. This supports its placement within an endemic cichlid radiation.

Hidden biodiversity in an ancient lake: phylogenetic congruence between Lake Tanganyika tropheine cichlids and their monogenean flatworm parasites

The stunning diversity of cichlid fishes has greatly enhanced our understanding of speciation and radiation. Little is known about the evolution of cichlid parasites. Parasites are abundant components of biodiversity, whose diversity typically exceeds that of their hosts. In the first comprehensive phylogenetic parasitological analysis of a vertebrate radiation, we study monogenean parasites infecting tropheine cichlids from Lake Tanganyika. Monogeneans are flatworms usually infecting the body surface and gills of fishes. In contrast to many other parasites, they depend only on a single host species to complete their lifecycle. Our spatially comprehensive combined nuclear-mitochondrial DNA dataset of the parasites covering almost all tropheine host species (N = 18), reveals species-rich parasite assemblages and shows consistent host-specificity. Statistical comparisons of host and parasite phylogenies based on distance and topology-based tests demonstrate significant congruence and suggest that host-switching is rare. Molecular rate evaluation indicates that species of Cichlidogyrus probably diverged synchronically with the initial radiation of the tropheines. They further diversified through within-host speciation into an overlooked species radiation. The unique life history and specialisation of certain parasite groups has profound evolutionary consequences. Hence, evolutionary parasitology adds a new dimension to the study of biodiversity hotspots like Lake Tanganyika.

Ancyrocephalidae (Monogenea) of Lake Tanganyika: I: Four new species of Cichlidogyrus from Ophthalmotilapia ventralis (Teleostei, Cichlidae), the first record of this family in the basin

Examination of gill parasites from Ophthalmotilapia ventralis (Boulenger, 1898) in Lake Tanganyika (Africa) revealed the presence of four new species of Monogenea, all members of Cichlidogyrus Paperna, 1960 (Ancyrocephalidae). In view of the systematic importance of haptoral structure, the fish host shows a remarkable diversity of morphological groups. Cichlidogyrus vandekerkhovei sp. nov. and C. makasai sp. nov. are especially characterized by the unusual length of the dorsal transverse bar auricles, while C. sturmbaueri sp. nov. is distinguished by the unique shape of the accessory piece of its male copulatory organ. Importantly, C. centesimus sp. nov. displays a number of features new to the genus, namely a spirally coiled thickening at the end of the penis, the absence of an accessory piece in the genital apparatus, and a hitherto unknown uncinuli configuration in the haptor. This is the first record of ancyrocephalid parasites from the Tanganyika basin. Some mechanisms possibly contributing to this yet unknown diversity are discussed, identifying topics deserving further scientific scrutiny.

Molecular phylogeny of monogeneans parasitizing African freshwater Cichlidae inferred from LSU rDNA sequences

The African freshwater fish of Cichlidae are parasitized by five genera of monogeneans belonging to Dactylogyridea. Ectoparasitic Scutogyrus, Onchobdella, and the highly diversified Cichlidogyrus represent three genera located on the gills, while the endoparasitic Enterogyrus and Urogyrus are located in the stomach and the urinary bladder, respectively. Representatives of four dactylogyridean genera (except for Urogyrus) were collected from seven cichlid species in West Africa. The aim of this study was to investigate the phylogenetic relationships between ectoparasitic and endoparasitic dactylogyridaen monogeneans specific to African freshwater Cichlidae and other representatives of Dactylogyridae, including a wide range of species from both freshwater and marine environments. All phylogenetic analyses point to the polyphyletic origin of the subfamily Ancyrocephalinae. Both Enterogyrus and Onchobdella were found to be monophyletic. The phylogenetic position of Scutogyrus longicornis was placed within the Cichlidogyrus species, which suggests the non-monophyly of Cichlidogyrus. Therefore, we have proposed a taxonomical revision of the species recently considered to be Scutogyrus. However, these four dactylogyridean genera-specific to cichlids do not form a monophyletic group. Using LSU rDNA analyses, we found that Enterogyrus and Onchobdella form a clade with Protogyrodactylus, i.e., the parasite species does not live in cichlids, which suggests that endoparasitism in cichlid monogeneans is not an ancestral feature.

Cichlids: A Host of Opportunities for Evolutionary Parasitology

Thanks to high species diversity and a broad range of speciation mechanisms, cichlid fishes represent a textbook model in evolutionary biology. They are also of substantial economic value. Despite this importance, cichlid parasites remain understudied, although some are more diverse than their hosts. They may offer important insights into cichlid evolution and the evolution of host-parasite interactions. We review five major lines of research conducted on cichlid parasites so far: the study of parasite diversity and speciation; the role of parasites in cichlid diversification; the evolutionary ecology of host specificity; historical biogeography; and biological invasions. We call for more research in these areas and suggest approaches to valorise the potential that cichlid parasites hold for the study of evolutionary parasitology.

Contrasting parasite communities among allopatric colour morphs of the Lake Tanganyika cichlid Tropheus

BackgroundAdaptation to different ecological environments is thought to drive ecological speciation. This phenomenon culminates in the radiations of cichlid fishes in the African Great Lakes. Multiple characteristic traits of cichlids, targeted by natural or sexual selection, are considered among the driving factors of these radiations. Parasites and pathogens have been suggested to initiate or accelerate speciation by triggering both natural and sexual selection. Three prerequisites for parasite-driven speciation can be inferred from ecological speciation theory. The first prerequisite is that different populations experience divergent infection levels. The second prerequisite is that these infection levels cause divergent selection and facilitate adaptive divergence. The third prerequisite is that parasite-driven adaptive divergence facilitates the evolution of reproductive isolation. Here we investigate the first and the second prerequisite in allopatric chromatically differentiated lineages of the rock-dwelling cichlid Tropheus spp. from southern Lake Tanganyika (Central Africa). Macroparasite communities were screened in eight populations belonging to five different colour morphs.ResultsParasite communities were mainly composed of acanthocephalans, nematodes, monogeneans, copepods, branchiurans, and digeneans. In two consecutive years (2011 and 2012), we observed significant variation across populations for infection with acanthocephalans, nematodes, monogeneans of the genera Gyrodactylus and Cichlidogyrus, and the copepod Ergasilus spp. Overall, parasite community composition differed significantly between populations of different colour morphs. Differences in parasite community composition were stable in time. The genetic structure of Tropheus populations was strong and showed a significant isolation-by-distance pattern, confirming that spatial isolation is limiting host dispersal. Correlations between parasite community composition and Tropheus genetic differentiation were not significant, suggesting that host dispersal does not influence parasite community diversification.ConclusionsSubject to alternating episodes of isolation and secondary contact because of lake level fluctuations, Tropheus colour morphs are believed to accumulate and maintain genetic differentiation through a combination of vicariance, philopatric behaviour and mate discrimination. Provided that the observed contrasts in parasitism facilitate adaptive divergence among populations in allopatry (which is the current situation), and promote the evolution of reproductive isolation during episodes of sympatry, parasites might facilitate speciation in this genus.

A recent inventory of the fishes of the north-western and central western coast of Lake Tanganyika (Democratic Republic Congo)

Background. Despite the importance of Lake Tanganyikas biodiversity for science and the livelihoods of the riparian people, high-resolution surveys of the fish biodiversity are sparse and fragmentary, especially along the western (Congolese) shoreline. The coast suffers locally from intensive human activities and lacks adequate protective measures or nature reserves. However, in view of the intra-lacustrine endemism of this fish fauna, conservation needs to be managed lake-wide at a fine scale, necessitating detailed inventories on fish species distribution. The study aims at updating knowledge on fish diversity and distribution along the north-western and central western shores of Lake Tanganyika. Materials and methods. Fish specimens were collected using gill-and seine nets, by snorkelling and SCUBA diving, and through purchases on the local markets. Results. Over 28 locations were sampled, and 84 cichlid- and 30 non-cichlid fish species (belonging to Protopteridae, Clupeidae, Cyprinidae, Alestidae, Claroteidae, Clariidae, Malapteruridae, Mochokidae, Poeciliidae, Latidae, and Mastacembelidae) collected. Conclusion. Our records substantially expand the known range of fish species in a range of habitats. As numerous specimens are hard to assign to nominal species, a taxonomic revision of a number of genera is underway. It should take into account intraspecific geographic variation.