Friday, May 18, 2012



Statistical phylogenetic analysis of 111 5.85 and partial – 28s ribosomal DNA sequences  ( total aligned length = 434 nucleotides) including jellyfishes representing approximately 14% of known scyphozoan romedusae constitute a fifth cnidarian class (Staurozoa) basal to a monophyletic Medusozoa (= Cubozoa, Hydrozoa, and Scyphozoa). Phylogenetic relationships among the medusozoans are generally poorly resolved, but support is found for reciprocal monophyly of the Cubozoa, Hydrozoa, Corontatae and Dis-comedusae (= Semaeostomeae  + Rhizostomeae). In addition, a survey of pairwise sequence differences in Internal Transcribed  Spacer One within morphospecies indicates that  scyphozoan species diversity may be approximately twice  recent estimates based on morphological analysis. These results highlight difficulties with traditional morphological treatments including terminology that obfuscates homologies. By integrating  molecular phylogenetic analysis with  old and new  morphological, behavioural, developmental, physiological, and other data, a much richer understanding of the biodiversity and evolution of jellyfishes is achievable.

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