The clade Ecdysozoa, perplexities and questions |
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Authors: | Giovanni Pilato,Maria Grazia Binda,Olga Biondi,Vera D&rsquo Urso,Oscar Lisi,Alessandro Marletta,Santa Maugeri,Vittorio Nobile,Giancarlo Rappazzo,Giorgio Sabella,Francesca Sammartano,Giuseppe Turrisi,Fabio Viglianisi |
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Affiliation: | Department of Animal Biology “Marcello La Greca”, University of Catania, Via Androne 81, I-95124 Catania, Italy |
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Abstract: | A relatively new clade, the Ecdysozoa [Aguinaldo et al., 1997. Nature 387, 489-493] was raised based on the 18S ribosomal DNA sequences that indicate a close relationship between the moulting phyla (Arthropoda, Tardigrada, Onychophora, Nematoda, Nematomorpha, Kinorhyncha, Lorificera and Priapula), from which the Annelida, with other phyla, are excluded.However, the authors here expressed puzzlement about this conclusion. In particular they stressed that: (a) ecdysis might not be an autapomorphy for the Ecdysozoa; (b) some Ecdysozoa phyla are unrelated from one another with regard to morphology and embryogeny; (c) the annelids have a body architecture that is more similar to arthropods than some of the Ecdysozoa; (d) the annelids are moulting animals; (e) some phyla excluded from the new clade (e.g. the gastrotrichs), probably carry out a gradual ecdysis by flaking similar to that of the polychaetes.The authors concluded that the clade Ecdysozoa appears to be phylogenetically unconvincing. |
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Keywords: | Ecdysozoa Ecdysis of annelids Comments Evaluations Unjustified clade |
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