Platyhelminthes
The phylum Platyhelminthes comprises dorso-ventrally flattened worms commonly known as flatworms (from the Greek platys, meaning flat, and helminthos, meaning worm) (for a general overview of this phylum, see Hyman 1951; Rieger et al. 1991). Platyhelminth
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Platyhelminthes Teresa Adell, José M. Martín-Durán, Emili Saló, and Francesc Cebrià
Chapter vignette artwork by Brigitte Baldrian. © Brigitte Baldrian and Andreas Wanninger. T. Adell • E. Saló (*) • F. Cebrià Department of Genetics, Faculty of Biology, Institute of Biomedicine, University of Barcelona, Av. Diagonal 643, edifici Prevosti, planta 1, Catalunya, Barcelona 08028, Spain e-mail: [email protected] J.M. Martín-Durán Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate, 55, Bergen 5008, Norway
A. Wanninger (ed.), Evolutionary Developmental Biology of Invertebrates 2: Lophotrochozoa (Spiralia) DOI 10.1007/978-3-7091-1871-9_3, © Springer-Verlag Wien 2015
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INTRODUCTION
Archoophora
The phylum Platyhelminthes comprises dorsoventrally flattened worms commonly known as flatworms (from the Greek platys, meaning flat, and helminthos, meaning worm) (for a general overview of this phylum, see Hyman 1951; Rieger et al. 1991). Platyhelminthes are one of the largest animal phyla after arthropods, mollusks, and chordates and includes more than 20,000 species, more than half of which are parasitic flatworms. Free-living flatworms (classically referred to as ‘Turbellaria’) live in a large variety of habitats, from freshwater springs, rivers, lakes, and ponds to the ocean and moist terrestrial habitats. Their size ranges from microscopic worms to the 30 m long tapeworms found in the sperm whale. Free-living flatworms are most often white, brown, grey, or black; polyclads
(marine flatworms) and terrestrial species usually display bright colours and patterns. Molecular phylogenetic studies place the Platyhelminthes within the Spiralia clade. The most recent internal phylogenies support the subdivision of the Platyhelminthes into two main groups: the earliest branching lineages grouped into the paraphyletic ‘Archoophora’ and the more divergent monophyletic Neoophora (Laumer and Giribet 2014; Riutort et al. 2012). The ‘Archoophora’ includes those groups with endolecithal eggs. They are exclusively free-living organisms and are classified into three orders: Catenulida, Polycladida, and Macrostomida (Fig. 3.1). The Neoophora includes all groups with ectolecithal eggs. It comprises several free-living orders, together with the parasitic groups (the classes Trematoda, Cestoda, and Monogenea) united under the monophyletic Neodermata.
Catenulida Catenulida (Stenosum sthenum)
Polycladida Macrostomorpha
Polycladida (Prosthiostomum siphunculus) Prorhynchida Lecithoepitheliata Gnosonesimida Macrostomorpha (Marcostomum lignano)
Neoophora
Proseriata Bothrioplanida
Prothynchida (Geocentrophora sphyrocephala) Neodermata Trematoda, Cestoda, Monogenea Rhabdocoela
Proseriata (Monocelis fusca)
Fecampiida Rhabdocoela (Rhynchomesostoma rostratum) Tricladida Prolecithophora
Fig. 3.1 Phylogenetic consensus tree of Platyhelminthes. The phylogenetic classification is based on Laumer and Giribet (2014), in which the former Lecithoepitheliata appears as a paraphyletic group, now d
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