Modularity in attachment organs of African Cichlidogyrus (Platyhelminthes: Monogenea: Ancyrocephalidae) reflects phylogeny rather than host specificity or geographic distribution



    Corresponding author
    1. UMR 5244 CNRS EPHE UPVD, Biologie et Écologie Tropicale et Méditerranéenne, Université de Perpignan Via Domitia, 66860 Perpignan cedex, France
    2. USR 3278 CNRS-EPHE, Centre de Recherches Insulaires et Observatoire de l’Environnement (CRIOBE), BP 1013, Papetoai Moorea, French Polynesia
    3. Present Address:
      UMR ECOBIOP INRA-UPPA. Écologie Comportementale et Biologie des Populations de Poissons
      a) Pôle d'Hydrobiologie de Saint Pée sur Nivelle, INRA
      Quartier Ibarron, 64310 Saint Pée sur Nivelle, France
      b) UPPA, UFR Sciences & Techniques de la Côte Basque
      1 Allée du parc Montaury, 64600 Anglet, France
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    1. IRD (ex ORSTOM), UR 203/UMR 5554, ISE-M
      Université Montpellier II – CC 065, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
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    1. Laboratory of Animal Diversity and Systematics, Biology Department, Katholieke Universiteit Leuven, Debériotstraat 32, B-3000 Leuven, Belgium
    2. Ichthyology Unit, African Zoology Department, Royal Museum for Central Africa, Leuvensesteenweg 13, B-3080 Tervuren, Belgium
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Cichlidogyrus spp. (Monogenea, Ancyrocephalidae) are common parasites of cichlid fishes from Africa and the Levant. They display important morphological variation in their attachment apparatus and infect a broad host spectrum throughout a wide geographic range. Thus, they offer an interesting model to investigate to what extent the phenotypic variability of the attachment organ among congeners is related to host specificity, geographic/environmental components, or phylogeny. A geometric morphometric approach was carried out to analyse the shape variation of sclerotized structures of the attachment organ within 66 African species of the genus Cichlidogyrus. The interspecific shape comparison supports the presence of three main morphological configurations, each consisting of a given combination of particular sclerite shapes. Moreover, data emphasize strong coordination and integration (shape co-variation) among the different sclerites jointly forming the attachment organ. Although attachment apparatuses are usually considered to be the result of adaptive processes and must be adapted to the hosts and local environmental conditions, we found no relationship between these clusters and host specificity or geographical distribution. Nevertheless, groups are partially congruent with those obtained with the molecular phylogeny of a subset of species, suggesting a phylogenetic constraint rather than an adaptation to either hosts or environment. Because of the necessity to form a functional entity, modularity within attachment organ imposes important evolutionary constraint. This provides new insights into the evolvability of attachment organs, as well as into the morphological basis of host specificity and host–parasite co-evolutionary interaction in helminth parasites. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 694–706.