Ecdysozoa versus Articulata: clades, artifacts, prejudices

The claim that monophyly of the Ecdysozoa is caused by chance similarities in 18S rDNA sequences (Wagele et al., J. Zool. Syst. Evol. Res. 37, 211-223 , 1999) is re-analysed from the cladistic point of view. It is shown that t he molecular characters supporting the Ecdysozoa do not behave as 'noisy' i n empirical studies that use the sensitivity analysis and character congrue nce approaches. The 'anti-noise' methodology proposed by Wagele ct al. (199 9) is unable to identify true misinformative data. The monophyly of the Art iculata ( = Annelida + Panarthropoda), proposed by Wagele et al. (1999), is contradicted by all molecular data that support either Ecdysozoa (includin g Panarthropoda), or Lophotrochozoa (including Annelida), or usually both.