PHYLOGENETIC-RELATIONSHIPS AND GENETIC DISTANCES BETWEEN SOME MONOSTILIFEROUS INTERSTITIAL NEMERTEANS (OTOTYPHLONEMERTES, HOPLONEMERTEA, NEMERTEA) INDICATED FROM THE 16S RIBOSOMAL-RNA GENE

Part of the 16S rRNA mitochondrial gene is used to reconstruct the rel ationships within five populations (representing three currently recog nized species) of interstitial nemerteans (Ototyphlonemertes, Hoplonem ertea, Nemertea), and to assess genetic divergence between representat ives of these populations. The non-helicophoran individuals form a mon ophyletic sister-group to the helicophoran taxon, which further resolv es a previous hypothesis based on morphological characters. The small nucleotide differences between some of the populations are within leve ls expected for panmictic populations and fail to distinguish them gen etically; without applying a phylogenic perspective, some of the popul ations may be allocated into paraphyletic species assemblages. (C) 199 8 The Linnean Society of London.