Freshwater planarian diversity (Platyhelminthes: Tricladida: Dugesiidae) in Madagascar: new species, cryptic species, with a redefinition of character states

摘要

The present paper describes three new species of freshwater flatworm of the genus Dugesia from Madagascar, by applying an integrative approach to taxonomy, combining morphological and molecular information. Further, molecular data uncovered a cryptic species diversity, enabling taxonomic assignment of several asexual populations to already known species and thus pointing to at least two more species of the genus Dugesia present on Madagascar. The paper redefines several character state conditions in species of Dugesia, relating to three types of accessory structures of the copulatory apparatus: penial annexes, atrial folds and valves, and adenodactyls. It also provides a more precise definition of character states concerning the course of the ejaculatory duct through the penis papilla. In order to be able to examine the taxonomic status, phylogenetic position and biogeography of the Malagasy Dugesia species, molecular phylogenetic analyses were performed on many populations from Madagascar and also on representatives of 27 species from across the geographic range of the genus. Our results show that Madagascar is not only rich in number of species but also in genetic diversity, thus highlighting that the biodiversity and endemicity of Malagasy freshwater planarians has been underestimated.