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Abstract Analyses of the primary structure of the 18S rRNA gene and D3 segment of the 28S rRNA, as well as evidence from the secondary structure of the SSU rRNA V7 region, suggest that Anoplostoma rectospiculum (Anoplostomatidae) has closer relationships to the family Enoplidae than to the Oncholaimidae. In phylogenetic trees derived from full length SSU rRNA gene and partial LSU rRNA gene (D3 expansion segment) sequence analyses, A. rectospiculum exhibits long branches. The associated artefacts of long branch attraction (LBA) are circumvented because of the presence of an undoubted molecular synapomorphy – a low homoplastic 1. b. p. insertion in helix 43 of the SSU rRNA which is shared jointly by Anoplostomatidae and Enoplidae. Analysis of low homoplastic apomorphic characters is considered to be a tool for testing phylogenies against LBA artefacts. |
